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The Psychophisics Toolbox
... Stimuli were programmed in MATLAB version 2015b using the Psychophysics Toolbox version 3.0.12 (Brainard, 1997; Pelli, 1997). Visual stimuli were presented on a ViewPixx custom LCD monitor with a screen resolution of 1920 Â 1080 pixels and a vertical refresh rate of 120 Hz. ...
... Apparatus and stimuli. Stimuli were programmed in MATLAB version 7.9 using the Psychophysics Toolbox version 3 (Brainard, 1997; Pelli, 1997). Visual stimuli were presented on a Sony Triniton CPD-G500 22-in. ...
We examined the recently discovered phenomenon of Adaptation-Induced Blindness (AIB), in which highly visible gratings with gradual onset profiles become invisible after exposure to a rapidly flickering grating, even at very high contrasts. Using very similar stimuli to those in the original AIB experiment, we replicated the original effect across multiple contrast levels, with observers at chance in detecting the gradual onset stimuli at all contrasts. Then, using full-contrast target stimuli with either abrupt or gradual onsets, we tested both the orientation tuning and interocular transfer of AIB. If, as the original authors suggested, AIB were a high-level (perhaps parietally mediated) effect resulting from the 'gating' of awareness, we would not expect the effects of AIB to be tuned to the adapting orientation, and the effect should transfer interocularly. Instead, we find that AIB (which was present only for the gradual onset target stimuli) is both tightly orientation-tuned and shows absolutely no interocular transfer, consistent with a very early cortical locus.
... The Psychophysics Toolbox (Brainard, 1997;Pelli, 1997) in the Matlab programming environment was used to create stimuli on a Dell Optiplex desktop. A Christie DLV1400-DX DLP projector (spatial resolution: 1024 × 768 pixels, refresh rate: 60 Hz) was used to back-project the stimuli onto a display screen at the head end of the bore of the magnet. ...
... Third, we performed the calculation assuming an even distribution of pRF fits across the stimulus space, but VFMs along dorsal and ventral pathways, for example, have been shown to have clear differences in cortical magnification (e.g., Brainard, 1997;Kastner et al., 2001;Press et al., 2001;Huk et al., 2002;Dougherty et al., 2003;Brewer et al., 2005;Wandell et al., 2007;Brewer and Barton, 2012b). In such cases, the number of rows is larger than the number of evenly divided intervals, meaning that the exponential component M is now larger than the denominator of 1/M or 3/M, above. ...
The cortical hierarchy of the human visual system has been shown to be organized around retinal spatial coordinates throughout much of low- and mid-level visual processing. These regions contain visual field maps (VFMs) that each follows the organization of the retina, with neighboring aspects of the visual field processed in neighboring cortical locations. On a larger, macrostructural scale, groups of such sensory cortical field maps (CFMs) in both the visual and auditory systems are organized into roughly circular cloverleaf clusters. CFMs within clusters tend to share properties such as receptive field distribution, cortical magnification, and processing specialization. Here we use fMRI and population receptive field (pRF) modeling to investigate the extent of VFM and cluster organization with an examination of higher-level visual processing in temporal cortex and compare these measurements to mid-level visual processing in dorsal occipital cortex. In human temporal cortex, the posterior superior temporal sulcus (pSTS) has been implicated in various neuroimaging studies as subserving higher-order vision, including face processing, biological motion perception, and multimodal audiovisual integration. In human dorsal occipital cortex, the transverse occipital sulcus (TOS) contains the V3A/B cluster, which comprises two VFMs subserving mid-level motion perception and visuospatial attention. For the first time, we present the organization of VFMs in pSTS in a cloverleaf cluster. This pSTS cluster contains four VFMs bilaterally: pSTS-1:4. We characterize these pSTS VFMs as relatively small at ∼125 mm2 with relatively large pRF sizes of ∼2–8° of visual angle across the central 10° of the visual field. V3A and V3B are ∼230 mm2 in surface area, with pRF sizes here similarly ∼1–8° of visual angle across the same region. In addition, cortical magnification measurements show that a larger extent of the pSTS VFM surface areas are devoted to the peripheral visual field than those in the V3A/B cluster. Reliability measurements of VFMs in pSTS and V3A/B reveal that these cloverleaf clusters are remarkably consistent and functionally differentiable. Our findings add to the growing number of measurements of widespread sensory CFMs organized into cloverleaf clusters, indicating that CFMs and cloverleaf clusters may both be fundamental organizing principles in cortical sensory processing.
... Stimuli were gray-scale, circular sine-wave gratings that varied across trials in spatial frequency (cycles per degree, CPD) and orientation (radians, rad). Each stimulus subtended approximately 5 degrees of visual angle and was displayed against a gray background using routines from the Psychophysics toolbox (Brainard, 1997). Stimuli were sampled from one of four possible distributions (illustrated in panel C of Figure 1), following the randomization technique developed by Ashby & Gott (1988) . ...
... Additional scans included a localizer, a GRE field map, and a DTI scan, none of which were used in the analyses presented here. The experiment was run using Psychophysics Toolbox (Brainard, 1997 ). During scanning, participants responded using the Lumina Response Pad System (model LU400-Pair), with the same finger–category mapping as during the in-lab prescreening . ...
Substantial evidence suggests that human category learning is governed by the interaction of multiple quali- tatively distinct neural systems. In this view, procedural memory is used to learn stimulus-response associa- tions, and declarative memory is used to apply explicit rules and test hypotheses about category membership. However, much less is known about the interaction between these systems: how is control passed between systems as they interact to influence motor resources? Here, we used fMRI to elucidate the neural correlates of switching between procedural and declarative categorization systems. We identified a key region of the cerebellum (left Crus I) whose activity was bidirectionally modulated depending on switch direction. We also identified regions of the default mode network (DMN) that were selectively connected to left Crus I during switching. We propose that the cerebellum—in coordination with the DMN—serves a critical role in passing control between procedural and declarative memory systems.
... Infrared videography was performed during all sessions (Microsoft LifeCam Cinema 720p HD Webcam with filter that blocks infrared light removed). The entire behavioral setup was controlled by a data acquisition device (USB 6212, National Instruments, Austin, TX) and custom-written Matlab scripts (Mathworks, Natick, MA) that used functionality from the Psychophysics toolbox [21] for precise temporal control of stimulus presentation. ...
Higher-order visual thalamus plays a fundamental but poorly understood role in attention-demanding tasks. To investigate how neuronal dynamics in higher-order visual thalamus are modulated by sustained attention, we performed multichannel electrophysiological recordings in the lateral posterior-pulvinar complex (LP/pulvinar) in the ferret ( Mustela putorius furo ). We recorded single unit activity and local field potential during the performance of the 5-choice serial reaction time task (5-CSRTT) that is used in both humans and animals as an assay of sustained attention. We found that half of the units exhibited an increasing firing rate during the delay period before stimulus onset (attention-modulated units). In contrast, the non-attention-modulated units responded to the stimulus, but not during the delay period. Spike-field coherence of only the attention-modulated neurons significantly increased from the start of the delay period until screen touch, predominantly in the theta frequency band. In addition, theta power and theta-gamma phase-amplitude coupling were elevated throughout the delay period. Our findings suggest that the theta oscillation plays a central role in orchestrating thalamic signaling during sustained attention.
Significance
Impaired sustained attention can be deadly, as illustrated by the number of motor vehicle accidents that are caused by drivers not reacting quickly enough to unexpected events on the road. Understanding how electrical signaling in higher-order visual nuclei, such as the LP/pulvinar, is modulated during tasks that require sustained attention is an important step in achieving a mechanistic understanding of sustained attention, which will eventually lead to new strategies to prevent and treat impairment in sustained attention.
... LCD monitor with a 60 Hz refresh rate controlled by a DELL computer equipped with Matlab r2016a (The MathWorks, Natick, MA) and Psychtoolbox 3.0.8 (Brainard, 1997;Pelli, 1997). Participants were seated 57 cm from the screen in a dark and quiet room, and used a chin rest to ensure consistent positioning. ...
Transcranial Random Noise Stimulation (tRNS) can enhance vision in the healthy and diseased brain. Yet, the impact of tRNS on large-scale cortical networks is still unknown. We investigated the impact of tRNS coupled with behavioral training on resting-state functional connectivity and attention. We trained human subjects for four consecutive days on two attention tasks, while receiving tRNS over the intraparietal sulci, the middle temporal areas, or sham stimulation. We measured resting state functional connectivity of nodes of the dorsal and ventral attention network (DVAN) before and after training. We found a strong behavioral improvement and increased connectivity within the DVAN after parietal stimulation only. Crucially, behavioral improvement positively correlated with connectivity measures. We conclude changes in connectivity is a marker for the enduring effect of tRNS upon behavior. Our results suggest that tRNS has strong potential to augment cognitive capacity in healthy individuals and promote recovery in the neurological population.
... The force-control and calculation tasks were constructed using Labview, 2017; National Instruments, Austin, TX). The N-back and reaction task programs were written in Matlab R2017a (MathWorks, Natick, MA), using Matlab's psychtoolbox [20]. ...
Dual-task performance often influences athletic competition results. Previous studies have suggested that cognitive tasks might improve dual-task performance. However, the factors that contribute to the manner in which cognitive tasks improve dual-task performance remain unknown. This study aimed to examine whether changes in brain activity induced by cognitive tasks are associated with improvement in dual-task performance. Nineteen young healthy adults performed an N-back and a reaction task on different days. A dual-task was constructed by combining a force-control and a calculation task. In the force-control task, participants adjusted their knee extension force according to target waves. In the calculation task, participants were required to subtract and respond to auditory stimuli delivered via earphones. We evaluated dual-task performance before and after performing each cognitive task. Additionally, we measured cerebral hemodynamic activity using near-infrared spectroscopy during the performance of each cognitive task. As a result, performing the N-back task improved performance in the force-control task under the dual-task setup. Furthermore, increase in oxyhemoglobin in a part of the right dorsolateral prefrontal cortex during the N-back task was positively correlated with improved force control during the subsequent dual-task. Cognitive tasks can be easily performed in a clinical field. Thus, cognitive tasks could be incorporated in traditional physical training. Future research should investigate whether the present findings can translate to improving performance in athletic competitions.
... The visual speller screen is designed in Matlab environment using Psychtoolbox [8] and is presented on a 25-inch LED (Dell Alienware AW2518HF) at 60 Hz refresh rate with a resolution of 1920 x 1080 pixels. Subjects were seated in front of the monitor screen at a distance of about 80 cm. ...
The purpose of this study is to develop a new methodology for designing stimulus sequences for cVEP BCI based on experimental studies regarding the behavior and the properties of the actual EEG responses of the visual system to coded visual stimuli, such that training time is reduced and the possible number of targets is increased. EEG from 8 occipital sites is recorded with 2000 samples/sec per channel, in response to visual stimuli presented on a computer monitor with 60Hz refresh rate. Onset and offset EEG responses to long visual stimulus pulses are obtained through 160-trial signal averaging. These edge responses are used to predict the EEG responses to arbitrary stimulus sequences using the superposition principle. A BCI speller which utilizes the target templates generated by this principle is also implemented and tested. It is found that certain short stimulus patterns can be accurately predicted by the superposition principle. BCI sequences that are constructed by combinations of these optimal patterns yield higher accuracy (95.9%) and ITR (57.2 bpm) compared to when the superposition principle is applied to conventional m-sequences and randomly generated sequences. Training time for the BCI application involves only the acquisition of the edge responses and is less than 4 minutes, and a huge number of sequences is possible. This is the first study in which cVEP BCI sequences are designed based on constraints obtained by observing the actual brain responses to several stimulus patterns.
... However, if as a community we could systematically share code of our online experiments and make it publicly available, then other researchers could build on top of or integrate parts of the code in their own online experiments and save a considerable amount of time and effort in devising, implementing and testing such intrinsic motivators. This strategy has been adopted widely and successfully in the Psychology community, of which Psychtoolbox [Bra97] is an example. ...
... Wheel-of-fortune task Participants completed 76 experimental trials on a computerized wheel-of-fortune task modified from Wu, van Dijk, and Clark (2015), using a spinner rather than highlighted Counterfactual Nature of Gambling Near-misses Y. Wu et al. segments to indicate gambling outcome. The task was programmed in Matlab, using the Psychophysics Toolbox extensions (Brainard, 1997). On each trial, the wheel was divided into four segments of different colors. ...
Research on gambling near-misses has shown that objectively equivalent outcomes can yield divergent emotional and motivational responses. The subjective processing of gambling outcomes is affected substantially by close but non-obtained outcomes (i.e. counterfactuals). In the current paper, we investigate how different types of near-misses influence self-perceived luck and subsequent betting behavior in a wheel-of-fortune task. We investigate the counterfactual mechanism of these effects by testing the relationship with a second task measuring regret/relief processing. Across two experiments (Experiment 1, n = 51; Experiment 2, n = 104), we demonstrate that near-wins (neutral outcomes that are close to a jackpot) decreased self-perceived luck, whereas near-losses (neutral outcomes that are close to a major penalty) increased luck ratings. The effects of near-misses varied by near-miss position (i.e. whether the spinner stopped just short of, or passed through, the counterfactual outcome), consistent with established distinctions between upward versus downward, and additive versus subtractive, counterfactual thinking. In Experiment 1, individuals who showed stronger counterfactual processing on the regret/relief task were more responsive to near-wins and near-losses on the wheel-of-fortune task. The effect of near-miss position was attenuated when the antici-patory phase (i.e. the spin and deceleration) was removed in Experiment 2. Further differences were observed within the objective gains and losses, between " clear " and " narrow " outcomes. Taken together, these results help substantiate the counterfactual mechanism of near-misses.
... com/en-us/product/extreme-3d-pro-joystick;) [49], which was connected to a Hewlett Packard Windows PC. We wrote the experiments in Matlab with the help of the Psychophysics Toolbox extensions [15,45,66]. The software displayed a Cartesian plane of the size of approximately 12x12 cm on the computer screen. ...
We compared the patterns of affiliative and dominant behavior displayed in male dyads where one participant has Asperger's syndrome (AS) with those displayed in male dyads with two neurotypical (NT) participants. Drawing on interpersonal theory, according to which affiliation and dominance constitute two orthogonal axes of the " interpersonal circle, " we used a computer-joystick apparatus to assess the participants' moment-to-moment affiliative and dominant behaviors throughout conversation. The patterns of affiliation and dominance were subsequently studied in relation to post-conversation questionnaires that targeted the interactional experiences of the participants in the two different types of dyads (AS dyads, NT dyads). We found the overall interpersonal notion of complementarity to hold for AS and NT dyads alike: greater affiliation in one participant invoked greater affiliation in the co-participant, and greater dominance invoked greater submissiveness in the co-participant. The AS and NT dyads, however, differed with regard to how affiliative and dominant behaviors related to each other during the time course of a single conversation. Furthermore, we found important differences between the AS and NT dyads in how the different patterns of affiliation and dominance were experienced by the participants. For example, a high level of affiliation synchrony was experienced in more negative terms by the participants in the AS dyads than by those in the NT dyads, while a high level of dominance coordination was experienced in more positive terms by the participants in the AS dyads than by those in the NT dyads. The paper increases understanding of the details of the interactional deficits associated with AS and of the conditions in which AS participants may get maximally positive interactional experiences. More generally, our study highlights the necessity to take the study of individual differences in the experiences of patterns of affiliation and dominance into the official agenda of empirical interaction research.
... Subjects were seated on a comfortable chair in a dark room and were instructed to respond as fast and accurate as possible. Stimuli were presented using Matlab Psychophysics Toolbox (Brainard, 1997) in a 21" CRT monitor with a resolution of 800×600 pixels, frame rate 80Hz, and viewing distance of 60cm. Therefore, each stimulus covered 11 • × 11 • of visual angle. ...
The human visual system contains a hierarchical sequence of modules that take part in visual perception at different levels of abstraction, i.e., superordinate, basic, and subordinate levels. One important question is to identify the “entry” level at which the visual representation is commenced in the process of object recognition. For a long time, it was believed that the basic level had a temporal advantage over two others. This claim has been challenged recently. Here we used a series of psychophysics experiments, based on a rapid presentation paradigm, as well as two computational models, with bandpass filtered images of five object classes to study the processing order of the categorization levels. In these experiments, we investigated the type of visual information required for categorizing objects in each level by varying the spatial frequency bands of the input image. The results of our psychophysics experiments and computational models are consistent. They indicate that the different spatial frequency information had different effects on object categorization in each level. In the absence of high frequency information, subordinate and basic level categorization are performed less accurately, while the superordinate level is performed well. This means that low frequency information is sufficient for superordinate level, but not for the basic and subordinate levels. These finer levels rely more on high frequency information, which appears to take longer to be processed, leading to longer reaction times. Finally, to avoid the ceiling effect, we evaluated the robustness of the results by adding different amounts of noise to the input images and repeating the experiments. As expected, the categorization accuracy decreased and the reaction time increased significantly, but the trends were the same. This shows that our results are not due to a ceiling effect. The compatibility between our psychophysical and computational results suggests that the temporal advantage of the superordinate (resp. basic) level to basic (resp. subordinate) level is mainly due to the computational constraints (the visual system processes higher spatial frequencies more slowly, and categorization in finer levels depends more on these higher spatial frequencies).
... The experiment was programmed and controlled using Matlab 7.7.0 (The MathWorks inc., Natick, MA, USA) and the Psychophysics Toolbox (Brainard, 1997;Pelli, 1997). Viewing distance was stable at 57 cm, supported by a chin and forehead rest. ...
Studies have demonstrated conscious and non-conscious priming of responses and of affect. Concerning response priming, presenting a target-related (congruent) distractor prior to a target typically facilitates target responses. This facilitation – the response-priming effect – is observed in comparison to a less related (incongruent) distractor. An incongruent distractor would interfere with the required response to the target. This response-priming effect is found with both conscious distractors, of which participants are aware, and non-conscious distractors, of which participants are not aware. In partly related research, distractors have also yielded affective priming effects on the evaluations of task-unrelated neutral symbols that followed the target: In comparison to the congruent condition, participants evaluated a neutral symbol presented after an incongruent distractor-target sequence as more negative. This affective priming effect was sometimes ascribed to the participants’ misattributions of distractor-target conflict to the unrelated neutral symbols. Here, we set out to test this possibility. If the misattribution explanation of affective priming holds true, affective priming would be stronger with non-conscious than with conscious distractors: Mostly the non-conscious distractors would mask distractor-target conflict as the true affect-origin and, therefore, invite participants’ misattribution of the primed affect to the neutral symbol in temporal vicinity. In contrast, only with conscious distractors, participants would be aware of distractor-target conflict as the true affect-origin and should, therefore, be better able to attribute their affective responses to the distractor-target relationship itself. In three experiments, we confirmed this prediction of a stronger affective priming effect in non-conscious than conscious distractor conditions, while at the same time showing conscious response-priming effects to even exceed non-conscious response-priming effects. Together, these results amount to a double dissociation between affective priming, being stronger with unconscious distractors, and response priming, being stronger with conscious distractors. This double dissociation supports the misattribution explanation and makes clear that the amount of distractor-elicited response conflict alone does not account for the amount of affective priming. Moreover, the participants’ unawareness of the distractors is critical for the amount of affective priming of neutral symbols in temporal vicinity.
... A MacBook Pro laptop with a 13 inch screen was used to display the stimuli and collect responses. The stimuli were presented and responses were collected using GNU Octave (Eaton, 2002) and the Psychtoolbox extensions for MatLab or Octave (Brainard, 1997). Statistical analyses were carried out using R (R Core Team, 2013). ...
Much of everyday language is vague, yet standard game-theoretic models do not find any utility of vagueness in cooperative situations. We report a novel experiment, the fourth in a series that aims to discern the utility of vagueness from the utility of other factors that come together with vagueness. We argue that the results support a view of vagueness where the benefits that vague terms exert are due to other influences that vagueness brings with it rather than to influences of vagueness itself.
... The apparatus, for all our experiments, was a MacBook Pro laptop with a 13 inch screen. The stimuli were presented using GNU Octave (Eaton, 2002) and the Psychophysics Toolbox extensions (Brainard, 1997). Results Response time data were preprocessed to remove outliers and erroneous responses. ...
NLG systems that generate text from numerical data must decide between alternative linguistic forms of the given numerical content, such as whether to use a precise or a vague expression. Currently there is little empirical data for these systems to draw on when making these decisions. We performed experiments with human readers in which participants responded to instructions in the form of referring expressions, where we manipulated whether the instruction used a vague or a crisp referring expression, in order to test the hypothesis that vague-ness reduces processing costs for the comprehender. Results indicate that people respond more quickly and accurately to vague linguistic expressions than to crisp numerical expressions , but that this benefit also accrues to precise terms that avoid numbers.
... Visual stimuli were created in MATLAB (The Mathworks Inc., Natick, MA, USA) using PsychToolbox [Brainard, 1997;Kleiner, Brainard, & Pelli, 2007] and displayed on a 15-inch monitor of a Dell Precision M4700 laptop driven at a resolution of 1366 x 768 pixels, at a refresh rate of 60 Hz. Participants viewed the monitor at a distance of 57 cm through anaglyph red-blue goggles (right lens: blue, left lens: red). ...
When different images are presented to the eyes, the brain is faced with ambiguity, causing perceptual bistability: visual perception continuously alternates between the monocular images, a phenomenon called binocular rivalry. Many models of rivalry suggest that its temporal dynamics depend on mutual inhibition among neurons representing competing images. These models predict that rivalry should be different in autism, which has been proposed to present an atypical ratio of excitation and inhibition [the E/I imbalance hypothesis; Rubenstein & Merzenich, 2003]. In line with this prediction, some recent studies have provided evidence for atypical binocular rivalry dynamics in autistic adults. In this study, we examined if these findings generalize to autistic children. We developed a child-friendly binocular rivalry paradigm, which included two types of stimuli, low- and high-complexity, and compared rivalry dynamics in groups of autistic and age- and intellectual ability-matched typical children. Unexpectedly, the two groups of children presented the same number of perceptual transitions and the same mean phase durations (times perceiving one of the two stimuli). Yet autistic children reported mixed percepts for a shorter proportion of time (a difference which was in the opposite direction to previous adult studies), while elevated autistic symptomatology was associated with shorter mixed perception periods. Rivalry in the two groups was affected similarly by stimulus type, and consistent with previous findings. Our results suggest that rivalry dynamics are differentially affected in adults and developing autistic children and could be accounted for by hierarchical models of binocular rivalry, including both inhibition and top-down influences. Autism Res 2017. ©2017 International Society for Autism Research, Wiley Periodicals, Inc.
... Stereoscopic stimuli were generated on a G5 Macintosh computer with Matlab (MathWorks, Natick, MA) and the Psychtoolbox (Brainard, 1997;Pelli, 1997). Stimuli were presented on a pair of CRT monitors (ViewSonic G225f) arranged in a mirror stereoscope at a viewing distance of 48 cm. ...
Although Panum’s limiting case has been extensively researched, only recently has it been discovered that in addition to horizontal disparity, the final perception of depth is influenced by (i) the vertical disparity gradient and (ii) the degree of cue conflict between 2D and 3D shapes. The present study examines the neural correlates of the two factors, using EEG while observers viewed several versions of stereoscopic stimuli, which depicted Panum’s limiting case. In these patterns the vertical disparity gradient was varied from 0.1 to 0.6, while the degree of cue conflict was manipulated from low to high. The ERP data showed that the amplitude of the N170 component (exogenous) was modulated by the vertical disparity gradient and cue conflict. In contrast, the N270 component (endogenous) was modulated by cue conflict only. Such findings demonstrate that both factors affect the perception of depth in Panum’s limiting case, but at different stages: the vertical disparity gradient at an early stage of processing (N170) and cue conflict at two stages (N170 and N270). Hence, vertical disparity gradient is related to low-level visual stimulus parameters and can modulate exogenous component, while cue conflict is related to both exogenous and endogenous components.
... All stimuli were surrounded by a black frame, which subtended a 117 visual angle of 10° X 7.5°. Stimulus presentation was controlled using MATLAB and 118 Psychtoolbox (Brainard, 1997 specific condition, and one--back image--level repetition of a specific pair (i.e., exemplar). ...
The human visual system has adapted to process cluttered scenes containing dozens of regularly arranged objects. The regularity among objects critically contributes to the efficiency of naturalistic vision. Recent studies investigating multiple object perception have demonstrated that visual cortex responses to multi-object displays can be accurately modeled by a linear combination of responses to individual objects, revealing independent processing of simultaneously presented objects. Here we use fMRI to show that this independence partly breaks down when objects are positioned according to frequently experienced configurations. Participants viewed pairs of objects that formed minimalistic two-‐ object scenes (e.g., a "living room" consisting of a sofa and television) presented in their regularly experienced spatial arrangement or in an irregular arrangement (with interchanged positions). Additionally, single objects were presented centrally and in isolation. Multi-voxel activity patterns evoked by the object pairs were modeled as the average of the response patterns evoked by the two single objects forming the pair. In two experiments, this approximation in object-selective cortex (OSC) was significantly less accurate for the regularly than the irregularly positioned pairs, indicating integration of individual object representations. More detailed analysis revealed a transition from independent to integrative coding along the posterior-‐ anterior axis of the visual cortex, with the independent component (but not the integrative component) being almost perfectly predicted by object selectivity across the visual hierarchy. These results reveal a transitional stage between individual object and multi-object coding in visual cortex, providing a possible neural correlate of efficient processing of regularly positioned objects in natural scenes.
... Stimuli were created using Matlab Psychtoolbox [24,25] with Matlab 2013 on a MacBook Pro and displayed on a 23 " Tobii TX-300 screen (resolution: 1920 x 1080 pixels, refresh rate 60 Hz). Eye movements were recorded using a Tobii TX-300 eye tracker (Tobii Technology, Danderyd , Sweden) at a sampling rate of 300Hz. ...
Optokinetic nystagmus (OKN), the reflexive eye movements evoked by a moving field, has recently gained interest among researchers as a useful tool to assess conscious perception. When conscious perception and stimulus are dissociated, such as in binocular rivalry—when dissimilar images are simultaneously presented to each eye and perception alternates between the two images over time—OKN correlates with perception rather than with the physical direction of the moving field. While this relationship is well established in healthy subjects, it is yet unclear whether it also generalizes to clinical populations, for example, patients with Parkinson’s disease. Parkinson’s disease is a motor disorder, causing tremor, slow movements and rigidity. It may also be associated with oculomotor deficits, such as impaired saccades and smooth pursuit eye movements. Here, we employed short-duration, onset binocular rivalry (2 s trial of stimulus presentation followed by 1 s inter-trial interval) with moving grating stimuli to assess OKN in Parkinson’s disease patients (N = 39) and controls (N = 29) of a similar age. Each trial was either non-rivalrous (same stimuli presented to both eyes) or rivalrous, as in binocular rivalry. We analyzed OKN to discriminate direction of stimulus and perception on a trial-by-trial basis. Although the speed of slow-phase OKN was slower in the patients, discriminability of conscious perception based on OKN was comparable between the groups. Treatment with anti-Parkinson drugs and deep brain stimulation improved motor ability of patients, but did not impact on OKN. Furthermore, OKN-based measures were robust and their latencies were shorter than manual button-based measures in both groups and stimulus conditions. To our knowledge, our study is the first to demonstrate that OKN can be used as a reliable indicator of conscious perception in binocular rivalry even in Parkinson’s disease patients in whom impaired manual dexterity may render button-press reports less reliable.
... Matlab (2010b) was used to associate the background noise to the auditory speech stimuli in a gating format at 0 dB SNR. To present speech stimuli in an audiovisual modality, Matlab and Psychophysics Toolbox (Brainard, 1997; Pelli, 1997; Kleiner et al., 2007) were used to synchronize auditory and visual speech stimuli. Detailed information about the synchronization of video and audio speech signal and the Matlab scripts used to gate them is available in Lidestam (2014). ...
This study aimed to examine the efficacy and maintenance of short-term (one-session) gated audiovisual speech training for improving auditory sentence identification in noise in experienced elderly hearing-aid users. Twenty-five hearing aid users (16 men and 9 women), with an average age of 70.8 years, were randomly divided into an experimental (audiovisual training, n = 14) and a control (auditory training, n = 11) group. Participants underwent gated speech identification tasks comprising Swedish consonants and words presented at 65 dB sound pressure level with a 0 dB signal-to-noise ratio (steady-state broadband noise), in audiovisual or auditory-only training conditions. The Hearing-in-Noise Test was employed to measure participants’ auditory sentence identification in noise before the training (pre-test), promptly after training (post-test), and 1 month after training (one-month follow-up). The results showed that audiovisual training improved auditory sentence identification in noise promptly after the training (post-test vs. pre-test scores); furthermore, this improvement was maintained 1 month after the training (one-month follow-up vs. pre-test scores). Such improvement was not observed in the control group, neither promptly after the training nor at the one-month follow-up. However, no significant between-groups difference nor an interaction between groups and session was observed. Conclusion: Audiovisual training may be considered in aural rehabilitation of hearing aid users to improve listening capabilities in noisy conditions. However, the lack of a significant between-groups effect (audiovisual vs. auditory) or an interaction between group and session calls for further research.
... All experiments were conducted in a quiet, dimly lit room. They were programmed using MATLAB with the Psychtoolbox extension (Brainard, 1997;Kleiner, Brainard, & Pelli, 2007;Pelli, 1997). The stimuli were presented on a 19-in flat-panel monitor with a 1280 pixels × 1024 pixels resolution. ...
There is a view that faces and objects are processed by different brain mechanisms. Different factors may modulate the extent to which face mechanisms are used for objects. To distinguish these factors, we present a new parametric multipart three-dimensional object set that provides researchers with a rich degree of control of important features for visual recognition such as individual parts and the spatial configuration of those parts. All other properties being equal, we demonstrate that perceived facelikeness in terms of spatial configuration facilitated performance at matching individual exemplars of the new object set across viewpoint changes (Experiment 1). Importantly, facelikeness did not affect perceptual discriminability (Experiment 2) or similarity (Experiment 3). Our findings suggest that perceptual resemblance to faces based on spatial configuration of parts is important for visual recognition even after equating physical and perceptual similarity. Furthermore, the large parametrically controlled object set and the standardized procedures to generate additional exemplars will provide the research community with invaluable tools to further understand visual recognition and visual learning.
... Participants in the standard group were seated in a sound dampened room in front of a 19 ′′ LCD computer monitor and used a standard USB mouse to complete the two experimental tasks -a visual oddball task and a reward-learning task—while EEG data were recorded via an ActiChamp system (see Figure 1for a time line for both tasks—the tasks themselves are described below). The experimental tasks were coded in MATLAB programming environment (Version 8.6, Mathworks, Natick, U.S.A.) using the Psychophysics Toolbox extension (Brainard, 1997). During performance of the oddball task participants saw a series of blue (MATLAB RGB value = [0 0 255]) and green (MATLAB RGB value = [0 255 0]) colored circles that appeared for 800–1,200 ms in the center of a dark gray screen (MATLAB RGB value = [108 108 108]). ...
In recent years there has been an increase in the number of portable low-cost electroencephalographic (EEG) systems available to researchers. However, to date the validation of the use of low-cost EEG systems has focused on continuous recording of EEG data and/or the replication of large system EEG setups reliant on event-markers to afford examination of event-related brain potentials (ERP). Here, we demonstrate that it is possible to conduct ERP research without being reliant on event markers using a portable MUSE EEG system and a single computer. Specifically, we report the results of two experiments using data collected with the MUSE EEG system—one using the well-known visual oddball paradigm and the other using a standard reward-learning task. Our results demonstrate that we could observe and quantify the N200 and P300 ERP components in the visual oddball task and the reward positivity (the mirror opposite component to the feedback-related negativity) in the reward-learning task. Specifically, single sample t-tests of component existence (all p's < 0.05), computation of Bayesian credible intervals, and 95% confidence intervals all statistically verified the existence of the N200, P300, and reward positivity in all analyses. We provide with this research paper an open source website with all the instructions, methods, and software to replicate our findings and to provide researchers with an easy way to use the MUSE EEG system for ERP research. Importantly, our work highlights that with a single computer and a portable EEG system such as the MUSE one can conduct ERP research with ease thus greatly extending the possible use of the ERP methodology to a variety of novel contexts.
... Computer tasks (experiments 1 and 3) were presented on a Dell Precision laptop (1366 × 768 pixels, 60 Hz) using MATLAB and elements of the Psychophysics Toolbox [39][40][41]. White stimuli were presented on a mid-grey background, at 61% Weber contrast. ...
Background: Studies reporting altered susceptibility to visual illusions in autistic individuals compared to typically developing individuals have been taken to reflect differences in perception (e.g., reduced global processing), but could instead reflect differences in higher-level decision-making strategies.
Methods: We measured susceptibility to two contextual illusions (Ebbinghaus, Müller-Lyer) in autistic children aged 6–14 years and typically developing children matched in age and non-verbal ability using three methods. In Experiment 1, we used a new 2-alternative-forced-choice method with a roving pedestal designed to minimise cognitive biases. Here, children judged which of two comparison stimuli was most similar in size to a reference stimulus. In Experiments 2 and 3, we used methods previously used with autistic populations. In Experiment 2, children judged whether stimuli were the ‘same’ or ‘different’, and in Experiment 3, we used a method-of-adjustment task.
Results: Across all tasks, autistic children were equally susceptible to the Ebbinghaus illusion as typically developing children. Autistic children showed a heightened susceptibility to the Müller-Lyer illusion, but only in the method-of-adjustment task. This result may reflect differences in decisional criteria.
Conclusion: Our results are inconsistent with theories proposing reduced contextual integration in autism and suggest that previous reports of altered susceptibility to illusions may arise from differences in decision-making, rather than differences in perception per se. Our findings help to elucidate the underlying reasons for atypical responses to perceptual illusions in autism and call for the use of methods that reduce cognitive bias when measuring illusion susceptibility.
... (MathWorks, USA) using the Psychophysics Toolbox extensions (PsychToolbox 3.0.8; Brainard, 1997;Pelli, 1997) and were viewed on a CRT monitor with a refresh rate of 100 Hz (resolution = 1280 × 960 pixels); presentation was controlled by a personal computer running the Windows XP operating system. Observers were seated at a distance of 60 cm from the monitor screen in a dark and quiet room. ...
... Each stimulus was presented for 500 ms accompanied by an auditory cue. The generation and presentation of the stimuli and the implementation of the psychophysical algorithms were carried out in Matlab and Psychtoolbox (Brainard, 1997;Pelli, 1997). In the 2-alternative forced choice procedure, the subjects identified the orientation of the gratings and responded with a keypad. ...
Optimal temporal modulation of the stimulus can improve foveal contrast sensitivity. This studyevaluates the characteristics oftheperipheral spatiotemporal contrast sensitivity function in normal-sighted subjects.The purpose is to identify a temporal modulation that can potentially improve the remaining peripheral visual function in subjects with central visual field loss. High contrast resolution cut-off for grating stimuli with four temporal frequencies (0, 5, 10 and 15 Hz drift) was first evaluated in the 10° nasal visual field.Resolution contrast sensitivity for all temporal frequencies was then measured at four spatial frequencies between 0.5 cycles per degree (cpd) and the measured stationary cut-off. All measurements were performed with eccentric optical correction. Similar to foveal vision, peripheral contrast sensitivity is highest for a combination of low spatial frequency and 5 to 10 Hz drift. At higher spatial frequencies, there was a decrease in contrast sensitivity with 15 Hz drift.Despitethis decrease, the resolution cut-off did not vary largely between the different temporal frequencies tested. Additional measurements of contrast sensitivity at 0.5 cpd and resolution cut-off for stationary (0 Hz) and 7.5 Hz stimuli performed at 10, 15, 20 and 25° in the nasal visual field also showed the same characteristics across eccentricities.
... A computer controlled the eyetracker and a second computer controlled the stimulus presentation. A Matlab SDK provided by SMI and elements of the Psychophysics toolbox were used for running the experiment (Brainard, 1997;Pelli, 1997). Code for data analysis was also written in Matlab (The MathWorks, Inc., Natick, MA, USA). ...
Multiple Sclerosis (MS) is likely to cause dysfunction of neural circuits between brain regions increasing brain working load or a subjective overestimation of such working load leading to fatigue symptoms. The aim of this study was to investigate if saccades can reveal the effect of fatigue in patients with MS.
... Stimuli were projected onto a screen at the back of the scanner bore, and participants viewed the stimuli through mirrored goggles. Tasks were programmed using the Psychophysics Toolbox version 2.54 (Brainard, 1997). At the end of the experiment, one trial was randomly selected to be carried out for potential payment in order to ensure incentive compatibility across all trials. ...
In the classic gain/loss framing effect, describing a gamble as a potential gain or loss biases people to make risk-averse or risk-seeking decisions, respectively. The canonical explanation for this effect is that frames differentially modulate emotional processes, which in turn leads to irrational choice behavior. Here, we evaluate the source of framing biases by integrating functional magnetic resonance imaging data from 143 human participants performing a gain/loss framing task with meta-analytic data from >8000 neuroimaging studies. We found that activation during choices consistent with the framing effect were most correlated with activation associated with the resting or default brain, while activation during choices inconsistent with the framing effect was most correlated with the task-engaged brain. Our findings argue against the common interpretation of gain/loss framing as a competition between emotion and control. Instead, our study indicates that this effect results from differential cognitive engagement across decision frames.
SIGNIFICANCE STATEMENT The biases frequently exhibited by human decision makers have often been attributed to the presence of emotion. Using a large fMRI sample and analysis of whole-brain networks defined with the meta-analytic tool Neurosynth, we find that neural activity during frame-biased decisions was more significantly associated with default behaviors (and the absence of executive control) than with emotion. These findings point to a role for neuroscience in shaping long-standing psychological theories in decision science.
... Viewing was binocular. The stimuli were created using Matlab and the Psychophysics Toolbox (Brainard, 1997; Pelli, 1997) and displayed on a 19-inch LCD Asus monitor with a refresh rate of 60 Hz. The screen resolution was 1920 × 1080 pixels. ...
Visual perception relies on low-level encoding of local orientation. Recent studies show an age-dependent impairment in orientation discrimination of stimuli embedded in external noise, suggesting that encoding of orientation is inefficient in older adults. In the present study we ask whether aging also reduces decoding, i.e., selecting the neural representations of target orientation while discarding those conflicting with it. We compared younger and older participants capability (mean age 24 and 68 years respectively) in discriminating whether the orientation of a Gabor target was left or right from the vertical. We measured (d′), an index of discrimination sensitivity, for orientation offset ranging from 1° to 12°. In the isolated target condition, d′ was reduced by aging and, in the older group, did not increase with orientation offset, thus resulting in a larger group difference at large than small orientation offsets from the vertical. Moreover, oriented elements in the background impaired more discrimination in the older group. However, distractors reduced more d′ when target-background orientation offset was large than when target and flanker had similar orientation, indicating that the effect of the background was not local, i.e., due to target inhibition by similarly oriented flankers. Altogether, these results indicate that aging reduces the efficiency in discarding the response to orientations differing from the target. Our results suggest that neural decision-making mechanisms, involving not only signal enhancement but also non-signal inhibition, become inefficient with age. This suggestion is consistent with the neurophysiological evidence of inefficient visual cortical inhibition in aging.
... Participants completed the experiment in a dimly lit curtained booth. The experiment was programmed in Matlab version R2010a using the Psychophysics Toolbox 3 [48,49]. The program was run on an Apple Mac Pro running Mac OSX Lion v. 10.7.5. ...
Studies suggest that familiar faces are processed in a manner distinct from unfamiliar faces and that familiarity with a face confers an advantage in identity recognition. Our visual system seems to capitalize on experience to build stable face representations that are impervious to variation in retinal input that may occur due to changes in lighting, viewpoint, viewing distance, eye movements, etc. Emerging evidence also suggests that our visual system maintains a continuous perception of a face's identity from one moment to the next despite the retinal input variations through serial dependence. This study investigates whether interactions occur between face familiarity and serial dependence. In two experiments, participants used a continuous scale to rate attractiveness of unfamiliar and familiar faces (either experimentally learned or famous) presented in rapid sequences. Both experiments revealed robust inter-trial effects in which attractiveness ratings for a given face depended on the preceding face's attractiveness. This inter-trial attractiveness effect was most pronounced for unfamiliar faces. Indeed, when participants were familiar with a given face, attractiveness ratings showed significantly less serial dependence. These results represent the first evidence that familiar faces can resist the temporal integration seen in sequential dependencies and highlight the importance of familiarity to visual cognition.
... We measured ADHD and normal participants' horizontal attentional bias with a sensitive grating-scales task (GST; Niemeier et al., 2007; Niemeier et al., 2008a; Niemeier et al., 2008b; Singh et al., 2011; also see Introduction) programmed in Matlab with the Psychophysics Toolbox extension (Brainard, 1997; Pelli, 1997). The GST task is inspired by the greyscales task (Mattingley et al., 1994; Nicholls et al., 1999) and is a relatively new measure of pseudoneglect. ...
Novel insights into the right-brain dominant functions of spatial attention and visual awareness may come from the peculiar observation that the attentional bias to the left in healthy individuals, called “pseudoneglect,” increases with visual noise superimposed onto test stimuli. However, it is unclear if this effect originates from noise activating early visual areas or causing higher-level cognitive interference. Cognitive distraction and load are known to induce neglect-like rightward biases in attention deficit hyperactivity disorder (ADHD). Therefore, here we tested pseudoneglect in 21 adults with ADHD using a grating-scales task (GST) in a high (HI) and a low (LO) spatial-frequency condition with superimposed pixel noise. As expected, we found that healthy participants (n = 32) displayed a “cross-over” of HI vs. LO biases that increased significantly with noise. However, the ADHD group exhibited no pseudoneglect or cross-over, and noise caused neither rightward nor leftward biases. Furthermore, ADHD individuals produced psychometric functions with normal slopes, indicating normal perceptual sensitivity. Our results show that pseudoneglect is altered in ADHD, but that pixel noise induces no neglect-like rightward biases as this would be expected if pixel noise caused cognitive interference. This suggests that pixel noise has a bottom-up perceptual effect on pseudoneglect. What is more, individuals with ADHD seem to lack activation of attentional functions via sensory stimulation despite intact visual processes. Our study adds to the growing literature of right hemisphere pathology in ADHD and the understanding of sensory noise as an activating factor of visuospatial attention and awareness.
... In order to prevent a potential confound of a compatibility effect due to sensorimotor interactions, we chose distant stimulation (i.e., hands) and response (i.e., feet) locations (Broadbent & Gregory, 1965;Fendrich, Hutsler, & Gazzaniga, 2004;Tamè & Longo, 2015). Stimulus presentation and response collection were controlled by a custom program written using MATLAB R2013b (Mathworks, Natick, MA) and the Psychtoolbox libraries (Brainard, 1997). Throughout the experiment, white noise was presented over closed-ear headphones (Sennheiser HD 439 Audio Headphones) to mask any sounds made by the tactile stimulators. ...
... 1). Matlab PsychoToolbox (Brainard, 1997) was used for stimulus presentation and response recording. Images were presented to different subjects in random orders. ...
Humans perform object recognition effortlessly and accurately. However, it is unknown how the visual system copes with variations in objects’ appearance and the environmental conditions. Previous studies have suggested that affine variations such as size and position are compensated for in the feed-forward sweep of visual information processing while feedback signals are needed for precise recognition when encountering non-affine variations such as pose and lighting. Yet, no empirical data exist to support this suggestion. We systematically investigated the impact of the above-mentioned affine and non-affine variations on the categorization performance of the feed-forward mechanisms of the human brain. For that purpose, we designed a backward-masking behavioral categorization paradigm as well as a passive viewing EEG recording experiment. On a set of varying stimuli, we found that the feed-forward visual pathways contributed more dominantly to the compensation of variations in size and position compared to lighting and pose. This was reflected in both the amplitude and the latency of the category separability indices obtained from the EEG signals. Using a feed-forward computational model of the ventral visual stream, we also confirmed a more dominant role for the feed-forward visual mechanisms of the brain in the compensation of affine variations. Taken together, our experimental results support the theory that non-affine variations such as pose and lighting may need top-down feedback information from higher areas such as IT and PFC for precise object recognition.
... A wireless microphone (DKW-1 GT, Nady Systems Inc., Emeryville, CA, USA) was used to measure the participants' verbal response. Precise control of visual cue and acquisition of verbal response were programmed in Matlab (The MathWorks, Natick, MA, USA) in the PsychToolbox environment (Brainard, 1997;Pelli, 1997). ...
Mobile phone use while walking can cause dual-task interference and increases safety risks by increasing attentional and cognitive demands. While the interference effect on cognitive function has been examined extensively, how perception of the environment and walking dynamics are affected by mobile phone use while walking is not well understood. The amount of visual information loss and its consequent impact on dynamic walking stability was examined in this study. Young adults (mean, 20.3 years) volunteered and walked on a treadmill while texting and attending to visual tasks simultaneously. Performance of visual task, field of regard loss, and margin of stability under dual-task conditions were compared with those of single-task conditions (i.e., visual task only). The results revealed that the size of visual field and visual acuity demand were varied across the visual task conditions. Approximately half of the visual cues provided during texting while walking were not perceived as compared to the visual task only condition. The field of regard loss also increased with increased dual-task cost of mobile phone use. Dynamic walking stability, however, showed no significant differences between the conditions. Taken together, the results demonstrate that the loss of situational awareness is unavoidable and occurs simultaneously with decrements in concurrent task performance. The study indicates the importance of considering the nature of attentional resources for the studies in dual-task paradigm and may provide practical information to improve the safe use of mobile phones while walking.
... Each rock picture subtended a visual angle of approximately 7 o x 7 o and was displayed on a white background. The experiment was conducted on PCs running MATLAB and the Psychophysics Toolbox (Brainard, 1997). For each participant, 4 of the 12 tokens of each subtype were randomly selected to serve as training stimuli, and 2 were randomly selected to serve as novel transfer stimuli. ...
Subjects learned to classify images of rocks into the categories igneous, metamorphic, and sedimentary. In accord with the real-world structure of these categories, the to-be-classified rocks in the experiments had a dispersed similarity structure. Our central hypothesis was that learning of these complex categories would be improved through observational study of organized, simultaneous displays of the multiple rock tokens. In support of this hypothesis, a technique that included the presentation of the simultaneous displays during phases of the learning process yielded improved acquisition (Experiment 1) and generalization (Experiment 2) compared to methods that relied solely on sequential forms of study and testing. The technique appears to provide a good starting point for application of cognitive-psychology principles of effective category learning to the science classroom.
... The experiments were presented on a 23-inch monitor (1920 × 1080, 60 Hz) using the Psychophysics Toolbox 49,50 in Matlab. Throughout the experiments, the background colour was set to grey (RGB = 0.78, 0.78, 0.78). ...
Attention can be directed at features and feature dimensions to facilitate perception. Here, we investigated whether feature-based-attention (FBA) can also dynamically weight feature-specific representations within multi-feature objects held in visual working memory (VWM). Across three experiments, participants retained coloured arrows in working memory and, during the delay, were cued to either the colour or the orientation dimension. We show that directing attention towards a feature dimension (1) improves the performance in the cued feature dimension at the expense of the uncued dimension, (2) is more efficient if directed to the same rather than to different dimensions for different objects, and (3) at least for colour, automatically spreads to the colour representation of non-attended objects in VWM. We conclude that FBA also continues to operate on VWM representations (with similar principles that govern FBA in the perceptual domain) and challenge the classical view that VWM representations are stored solely as integrated objects.
... For registration of manual responses, a standard USB keyboard was used. Event scheduling and response time measurement were controlled by Matlab, using the Psychophysics Toolbox (Brainard, 1997;Kleiner et al., 2007). All stimuli were white (RGB: 255, 255, 255), and appeared on a gray background (RGB: 160, 160, 160). ...
Visual search through previously encountered contexts typically produces reduced reaction times compared with search through novel contexts. This contextual cueing benefit is well established, but there is debate regarding its underlying mechanisms. Eye-tracking studies have consistently shown reduced number of fixations with repetition, supporting improvements in attentional guidance as the source of contextual cueing. However, contextual cueing benefits have been shown in conditions in which attentional guidance should already be optimal-namely, when attention is captured to the target location by an abrupt onset, or under pop-out conditions. These results have been used to argue for a response-related account of contextual cueing. Here, we combine eye tracking with response time to examine the mechanisms behind contextual cueing in spatially cued and pop-out conditions. Three experiments find consistent response time benefits with repetition, which appear to be driven almost entirely by a reduction in number of fixations, supporting improved attentional guidance as the mechanism behind contextual cueing. No differences were observed in the time between fixating the target and responding-our proxy for response related processes. Furthermore, the correlation between contextual cueing magnitude and the reduction in number of fixations on repeated contexts approaches 1. These results argue strongly that attentional guidance is facilitated by familiar search contexts, even when guidance is near-optimal. (PsycINFO Database Record
... Stimulus presentation and timing were controlled using the Psychophysics Toolbox software (Brainard, 1997). Stimuli were presented through a 55'' LCD digital TV screen. ...
Recent evidence for an evolved fear module in the brain comes from studies showing that adults, children and infants detect evolutionarily threatening stimuli such as snakes faster than non-threatening ones. A decisive argument for a threat detection system efficient early in life would come from data showing, in young infants, a functional threat-detection mechanism in terms of “what” and “where” visual pathways. The present study used a variant of Posner’s cuing paradigm, adapted to 7–11-month-olds. On each trial, a threat-irrelevant or a threat-relevant cue was presented (a flower or a snake, i.e., “what”). We measured how fast infants detected these cues and the extent to which they further influenced the spatial allocation of attention (“where”). In line with previous findings, we observed that infants oriented faster towards snake than flower cues. Importantly, a facilitation effect was found at the cued location for flowers but not for snakes, suggesting that these latter cues elicit a broadening of attention and arguing in favour of sophisticated “what–where” connections. These results strongly support the claim that humans have an early propensity to detect evolutionarily threat-relevant stimuli.
... Experiments were run on a Dell Precision M3800 laptop (2048 Â 1152 pixels, 60 Hz) using MATLAB (MathWorks, Cambridge, MA, USA) and elements of the Psychophysics Toolbox (Brainard, 1997;Kleiner, Brainard, & Pelli, 2007;Pelli, 1997). A yellow-bordered hard-edged circular aperture (15 diameter) and an anchor-shaped fixation point (0.57 ...
The vision of autistic people has been characterised as focused on detail, with a disinclination (or reduced ability) to integrate information into coherent ‘wholes’. In contrast to this view, we recently demonstrated enhanced integration of visual motion signals in autistic children compared to typically developing children. Here, we aimed to investigate the robustness of our finding of increased motion integration in autism with a new sample of children and to determine whether increased integration in autistic children would extend to a static, orientation judgement.
... The calibration was a 9 point matrix of crosses where the subject had to fixate the gaze. The experiment was controlled from a second monitor running MATLAB (MathWorks, Natick, MA) with Psychophysics Toolbox [11] and connected to the calibrated display. The eye tracking device was as well connected to the instructor's computer, so it could also be controlled by the same script in MATLAB. ...
Visual attention refers to the cognitive mechanism that allows us to select and process only the relevant information arriving at our eyes. Therefore, eye movements will have a significant dependency on visual attention. Saliency models, trying to simulate visual gaze and consequently, visual attention, have been continuously developed over the last years. Color information has been shown to play an important role in visual attention, and it is used in saliency computations. However, psychophysical evidence explaining the relationship between color and saliency is lacking. The results of the experiment will be presented aiming at studying and quantifying saliency of colors of different hues and lightness specified in CIELab coordinates. In the experiment, 12 observers were asked to report the number of color patches presented at random locations on a masking gray background. Eye movements were recorded using an SMI remote eye tracking system and being used to validate the reported data. In this paper, we will compare the reported data and visual gaze data for different colors and discuss implications for our understanding of color saliency and color processing.
... Participants sat approximately 67 cm away from a 17 00 CRT monitor (resolution: 1024 × 768, refresh-rate: 85 HZ) in a dimly lit room. The experiments were programmed using Psychtoolbox (Brainard, 1997;Pelli, 1997) implemented in MATLAB (www.mathworks.com). Six hundred colored images (1.89 × 1.89 ) of realworld objects were taken from the MIT dataset (http://cvcl.mit.edu/MM/). ...
Visual search is facilitated when observers search through repeated displays. This effect, termed contextual cueing (CC), reflects the exceptional ability of our cognitive system to utilize regularities embedded in the environment. Recent studies that tested visual search with real-world objects found that CC takes place even in heterogeneous search displays, but only when the identities (“what”) and locations (“where”) of the objects are both repeated. The purpose of the current study was to test whether the repetition of both “what” and “where” is not only necessary but also sufficient for CC. Consistent with previous results, Experiment 1 found robust CC when both the “what” and “where” information were repeated, and further revealed that the effect was not modulated by the number of search items. In contrast, Experiment 2 showed that the repetition of both objects’ identities and locations did not benefit the search when the two were not bound together. CC was also absent in Experiment 3, where the objects’ identities and locations were repeated together, however, target locations varied randomly. Together these results suggest that CC with real-world objects is robust, but critically depends on “what” and “where” binding as well as context-target associations.
... Visual feedback of the tip of the pen was provided by a 3-mm white dot. The 142 presentation of visual stimuli and the collection of hand trajectories were controlled using 143 custom MATLAB (Mathworks) program and the Psychophysics toolboxes (Brainard, 1997; 144 Pelli, 1997). Six different irregular white polygons were used ( Fig. 2A shows one of them). ...
Previous studies have revealed that visual and somatosensory information is processed as a function of its relevance during movement execution. We thus performed spectral decompositions of ongoing neural activities within the somatosensory and visual areas while human participants performed a complex visuomotor task. In this task, participants followed the outline of irregular polygons with a pen-controlled cursor. At unpredictable times, the motion of the cursor deviated 120° with respect to the actual pen position creating an incongruence between visual and somatosensory inputs, thus increasing the importance of visual feedback to control the movement as suggested in previous studies. We found that alpha and beta power significantly decreased in the visual cortex during sensory incongruence when compared to unperturbed conditions. This result is in line with an increased gain of visual inputs during sensory incongruence. In parallel, we also found a simultaneous decrease of gamma and beta power in sensorimotor areas which has not been reported previously. The gamma desynchronization suggests a reduced integration of somatosensory inputs for controlling movements with sensory incongruence while beta ERD could be more specifically linked to sensorimotor adaptation processes.
... The tasks were designed and presented using MATLAB 2013a and Psychophysics Toolbox (version 3.0.12) [35,36]. Each task comprised 6 blocks of 10 trials (i.e., 10 words) each. ...
... Stimulus presentation was controlled by MATLAB (MathWorks, Inc.) with Psychtoolbox (Brainard, 1997;Pelli, 1997). The visual stimuli were presented on a 19-in. ...
Studies have demonstrated that eye movements enhance visual memory. However, the role of eye movement in implicit learning is not clear. We investigated whether implicit learning of spatial configuration requires eye movement using the contextual cueing paradigm. Eye movements were restricted by instructing participants to maintain fixation on the center of a display during a visual search. The results demonstrated that contextual cueing occurs even without eye movements. Furthermore, contextual cueing effects were obtained more rapidly when eye movements were restricted compared to when eye movements were allowed. The findings suggest that eye movements mediate the learning progress in contextual cueing: stabilization of spatial layout representation by restriction of eye movements induces a rapid learning of configuration.
... The tasks were designed and presented using MATLAB 2013a and Psychophysics Toolbox (version 3.0.12) [35, 36]. Each task comprised 6 blocks of 10 trials (i.e., 10 words) each. ...
The role of the cerebellum in cognitive processing is increasingly recognized but still poorly understood. A recent study in this field applied cerebellar Transcranial Direct Current Stimulation (c-tDCS) to the right cerebellum to investigate the role of prefrontal-cerebellar loops in language aspects of cognition. Results showed that the improvement in participants' verbal response times on a verb generation task was facilitated immediately after cathodal c-tDCS, compared to anodal or sham c-tDCS. The primary aim of the present study is to replicate these findings and additionally to investigate possible longer term effects. A crossover within-subject design was used, comparing cathodal and sham c-tDCS. The experiment consisted of two visits with an interval of one week. Our results show no direct contribution of cathodal c-tDCS over the cerebellum to language task performance. However, one week later, the group receiving cathodal c-tDCS in the first visit show less improvement and increased variability in their verbal response times during the second visit, compared to the group receiving sham c-tDCS in the first visit. These findings suggest a potential negative effect of c-tDCS and warrant further investigation into long term effects of c-tDCS before undertaking clinical studies with poststroke patients with aphasia.
... The face images were presented using MATLAB, as well as custom routines and extensions from the Psychophysics and Video Toolbox (Brainard, 1997;Kleiner et al., 2007;Pelli, 1997) on a MacBook Pro laptop computer (Apple, Cupertino, CA). Stimuli were displayed on a 17-inch LCD monitor with a pixel resolution of 1600 3 1000 pixels and a mean luminance of 50.0 cd/m 2 (x ¼ 0.2783, y ¼ 0.3210 in CIE [Commission Internationale de l'Eclairage] u*, v* color space). ...
... Stimuli were presented at the center of a 17-in CRT screen (ViewSonic G75f, with 100 Hz refresh rate) on gray background (viewing distance = 90 cm). Stimulus presentation and response acquisition were handled using Psychophysics toolbox [77,78] for MATLAB (version 7.5.0, Mathworks, Natick, Massachusetts). ...
Predicting the timing of upcoming events enables efficient resource allocation and action preparation. Rhythmic streams, such as music, speech, and biological motion, constitute a pervasive source for temporal predictions. Widely accepted entrainment theories postulate that rhythm-based predictions are mediated by synchronizing low-frequency neural oscillations to the rhythm, as indicated by increased phase concentration (PC) of low-frequency neural activity for rhythmic compared to random streams. However, we show here that PC enhancement in scalp recordings is not specific to rhythms but is observed to the same extent in less periodic streams if they enable memory-based prediction. This is inconsistent with the predictions of a computational entrainment model of stronger PC for rhythmic streams. Anticipatory change in alpha activity and facilitation of electroencephalogram (EEG) manifestations of response selection are also comparable between rhythm- and memory-based predictions. However, rhythmic sequences uniquely result in obligatory depression of preparation-related premotor brain activity when an on-beat event is omitted, even when it is strategically beneficial to maintain preparation, leading to larger behavioral costs for violation of prediction. Thus, while our findings undermine the validity of PC as a sign of rhythmic entrainment, they constitute the first electrophysiological dissociation, to our knowledge, between mechanisms of rhythmic predictions and of memory-based predictions: the former obligatorily lead to resonance-like preparation patterns (that are in line with entrainment), while the latter allow flexible resource allocation in time regardless of periodicity in the input. Taken together, they delineate the neural mechanisms of three distinct modes of preparation: continuous vigilance, interval-timing-based prediction and rhythm-based prediction.
... Stimulus display and data collection were controlled by a PC (NVIDIA GeForce GT 430 graphics card) and the experiment was programmed in Matlab 7.8 (The MathWorks Inc., Natick, MA, USA) using Psychtoolbox 3.0.8 [23]. A combined chin-and forehead rest stabilized participants' head. ...
Dynamic visual acuity (DVA) is the ability to resolve fine spatial detail in dynamic objects during head fixation, or in static objects during head or body rotation. This ability is important for many activities such as ball sports, and a close relation has been shown between DVA and sports expertise. DVA tasks involve eye movements, yet, it is unclear which aspects of eye movements contribute to successful performance. Here we examined the relation between DVA and the kinematics of smooth pursuit and saccadic eye movements in a cohort of 23 varsity baseball players. In a computerized dynamic-object DVA test, observers reported the location of the gap in a small Landolt-C ring moving at various speeds while eye movements were recorded. Smooth pursuit kinematics—eye latency, acceleration, velocity gain, position error—and the direction and amplitude of saccadic eye movements were linked to perceptual performance. Results reveal that distinct eye movement patterns—minimizing eye position error, tracking smoothly, and inhibiting reverse saccades—were related to dynamic visual acuity. The close link between eye movement quality and DVA performance has important implications for the development of perceptual training programs to improve DVA.
... As mentioned before, Gabor patches (TuebingenCSTest, qCSF) and circular grating patches (FrACT, F.A.C.T.) were used as stimuli and presented by a Mac OSX, version 10.9.5 using the Psychophysics Toolbox Version 3.0.9 [32][33][34]. The possible orientations of both stimuli were depending on the test that was used -either 3AFC (orientation: 90°, 75° and 105°) for F.A.C.T. or 4AFC (orientation: 0°, 90°, 45° and 135°) for FrACT, qCSF and TuebingenCSTest. ...
Since contrast sensitivity (CS) relies on the accuracy of stimulus presentation, the reliability of the psychophysical procedure and observer’s attention, the measurement of the CS-function is critical and therefore, a useful threshold contrast measurement was developed. The Tuebingen Contrast Sensitivity Test (TueCST) includes an adaptive staircase procedure and a 16-bit gray-level resolution. In order to validate the CS measurements with the TueCST, measurements were compared with existing tests by inter-test repeatability, test-retest reliability and time. The novel design enables an accurate presentation of the spatial frequency and higher precision, inter-test repeatability and test-retest reliability compared to other existing tests.
The change of facial color and expression reflects our mental or physical condition. Previous behavioral studies indicated that there is a strong interaction between facial color and expression perception. This study investigated the contribution of facial color to expression recognition in blur images with the measurement of behavior and pupillary change. In the experiment, the face stimuli of facial colors (natural color, reddish) with different expressions (neutral, and anger) in 3 blur levels were presented. Participants performed a task of expression identification to the stimulus. Behavioral results indicated that the facial color has a significant contribution to expression recognition as blur level increases. Then, the results of pupillometry showed that the reddish-color provided the information necessary to identify anger. These results showed the contribution of facial color increases in both psychophysics and pupillary experiment as blur level increases, which suggested that facial color emphasizes the characteristics of specific facial expression.
A key question within systems neuroscience is to understand how the brain encodes spatially and temporally distributed local features and binds these together into one perceptual representation. Previous works in animal and human have shown that changes in neural synchrony occur during the perceptual processing and these changes are distinguished by the emergence of gamma-band oscillations (GBO, 30–80 Hz, centered at 40 Hz). Here, we used the mouse electroencephalogram to investigate how different cortical areas play roles in perceptual processing by assessing their GBO patterns during the visual presentation of coherently/incoherently moving random-dot kinematogram and static dots display. Our results revealed that GBO in the visual cortex were strongly modulated by the moving dots regardless of the existence of a global dot coherence, whereas GBO in frontal cortex were modulated by coherence of the motion. Moreover, concurrent GBO across the multiple cortical area occur more frequently for coherently moving dots. Taken together, these findings of GBO in the mouse frontal and visual cortex are related to the perceptual binding of local features into a globally-coherent representation, suggesting the dynamic interplay across the local/distributed networks of GBO in the global processing of optic flow.
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