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Effects on Face Recognition of Spatial-Frequency Information Contained in Inspection and Test Stimuli
Abstract
Researchers often assume a critical band of spatial frequencies is required for face recognition. Also, many studies have not measured the contrast required for recognition. On Day 1, observers viewed high-pass-filtered (HP), low-pass-filtered (LP), or unfiltered (UF) faces. On Day 2, they viewed a variety of faces, some of which were LP filtered, HP filtered, and UF. Observers adjusted contrast until they achieved both detection and recognition. Observers were most accurate and sensitive when filtered faces agreed in spatial-frequency content across days. Faces differing in spatial-frequency content were least well recognized. Unfiltered faces always fell between the 2 extremes. Observers generally used less contrast to recognize unfiltered than filtered faces. Correspondence of information between inspection and testing seemed more important than any particular range of frequencies.
... shape (these were placed on a black background). These differences in shape and colour of the two kinds of stimuli may have affected the ease with which they can be distinguished. Thus, the food stimuli may be less physically contrasting and, therefore, more difficult to distinguish than the abstract stimuli based on their physical properties (cf. Kornowski & Petersik, 2003). These latter two possible explanations both predict that the animals have more difficulty in discriminating between the two food stimuli than between the abstract stimuli. Also, these explanations are equally supported by the results of this study. We showed that subjects frequently chose the other food stimulus when a food stimulus w ...
... In Chapter 5 the good discriminability of the abstract pictures may have been due to the bright, contrasting colours. Furthermore, recent studies in humans do suggest that an increase in contrast is associated with better recognition of pictures (Wichmann et al., 2002; Kornowski & Petersik, 2003 ). In this study, therefore, colourfulness of stimuli was investigated as a stimulus feature that may affect discrimination performance. ...
... The reported importance of colour for discrimination performance (Harlow, 1945; Cole, 1953; Warren, 1954; Jarrard & Moise, 1971; Bartus et al., 1979; Rosenfeld & Van Hoesen, 1979) was not confirmed by our results. Nor do our results suggest that the reported positive effect of high levels of contrast for human recognition memory (Wichmann et al., 2002; Kornowski & Petersik, 2003) transfers to discrimination learning. Due to methodological differences a useful comparison of results can only be made with the study by Rosenfeld and Van Hoesen (1979). ...
In both humans and monkeys not all individuals show the same rate of age-related cognitive decline. One important factor to influence the rate of decline is extended exposure to elevated levels of glucocorticoids, which play a central role in the response to stress. Furthermore, studies with humans have suggested that the social environment influences such exposure to glucocorticoids. However, the complex social structure of human society complicates the investigation of the effects of the life time social environment on cognitive decline. The stable social structure of many monkey species does allow this investigation. The colony of long-tailed macaques (Macaca fascicularis) of the Utrecht University is especially suited for this. The social dominance relations of the females are stable and have been known for decades. Moreover, a low dominance status has been related to exposure to elevated levels of glucocorticoids. We aimed to confirm previously found results supporting the hypothesis that a history of low dominance is related to an acceleration of age-related cognitive decline. Fourteen female monkeys of various age and dominance classes were tested in a four-choice discrimination-reversal test. Subjects were temporarily isolated from their group based on voluntary co-operation, and tested with a computer operated touch screen. The results do not support this hypothesis. A number of theoretical and methodological issues are discussed in relation to this result. Further analyses revealed that high dominance status was related to relatively low levels of attention, which in turn were related to poor cognitive performance. This finding confounded the possibility to find the hypothesised effect. In an additional study the social groups were exposed to a loud noise to assess individual differences in the temperamental aspect of anxiety, which were then related to differences in behaviour and performance in the previous cognitive test. More anxious subjects paid less attention to the task and had a poor performance. However, this effect was found only for the experimentally naïve subjects. In the second part of this thesis the effects of stimulus parameters on cognitive performance are investigated. We hypothesised that biologically relevant 2-dimensional stimuli are more easily discriminated than pictures that the animals has no prior associations with. Also, bright and contrasting colours may improve performance compared to dull colours. In a relatively difficult cognitive task bright colours and high levels of contrast enhanced performance, while no such effect was found in a similar but less difficult task. Biological relevance of stimuli did not influence performance. This thesis underlines the possibilities and difficulties that testing individual cognitive performance of socially housed monkeys offer. Social dominance relations and individual characteristics strongly influence cognitive performance and complicate the study of other differences in cognitive abilities. Moreover, the parameters of the stimuli are important to consider in the design of a study as these may profoundly affect performance in more difficult tasks. It is recommended that in future studies a situation should be created in which the test is an integrated part of the animals' daily foraging behaviour, allowing larger sample sizes and longer study periods.
... That is, high-level visual processes (holistic vs. analytic) dedicated to faces would be rooted in the early segregation of low-level visual information provided at different spatial scales in the stimulus. Although a large number of studies have aimed at identifying the critical SF bands serving face recognition (e.g.,Costen, Parker, & Craw, 1994, 1996Fiorentini, Maffei, & Sandini, 1983;Gold, Bennett, & Sekuler, 1999;Hayes, Morrone, & Burr, 1986;Kornowski & Petersik, 2003;Liu, Collin, Rainville, & Chaudhuri, 2000;Näsänen, 1999;Parker & Costen, 1999;Tieger & Ganz, 1979), this hypothesis of a mapping between holistic/analytic processing of a face and the low/high extremes of the spatial frequency (SF) spectrum has neither been investigated directly by manipulating holistic processing nor systematically, that is, with spatially filtered faces. Indirect evidence that LSF may be critical for face holistic processing was provided byCollishaw and Hole (2000), who showed that blurred faces (i.e., preserving mostly LSF intensities) could still be recognized adequately unless they were presented upside down. ...
... For example, several studies have shown that face recognition optimally relies on an intermediate band of SF, between 8 and 16 cycles per face image (e.g.,Costen, Parker, & Craw, 1994, 1996Gold, Bennett, & Sekuler, 1999;Näsänen, 1999). More recent studies have qualified this observation by showing that the critical factor for optimal performance in such experiments is the overlap of SF bands across face stimuli presented at encoding and recognition stages (Collin, Liu, Troje, McMullen, & Chaudhuri, 2004;Kornowski & Petersik, 2003;Liu, Collin, Rainville, & Chaudhuri 2000). Third and perhaps most interestingly, the use of spatially filtered faces may yield new insights about the respective time course of holistic and featural face processes. ...
... In line with previous works contrasting categorization performance in LSF and HSF stimuli (e.g.,Goffaux, Gauthier, & Rossion, 2003;Goffaux, Hault, Michel, Vuong, & Rossion, 2005;Schyns & Oliva, 1999;Oliva & Schyns, 1997), LSF and HSF conditions excluded intermediate spatial frequencies (here 8 –32 cpf). Because several studies have shown that SF overlap between pairs of faces to match was more important for face recognition than absolute SF content (Collin, Liu, Troje, McMullen, & Chaudhuri, 2004;Kornowski & Petersik, 2003;Liu, Collin, Rainville, & Chaudhuri, 2000), subjects were asked to match pairs of faces presented in congruent frequency bands (e.g., 32 cpf to 32 cpf; 8 cpf to 8 cpf). Isolated features (eyes, nose, or mouth) were generated by cutting the relevant feature from filtered and full-spectrum versions of original and foil faces, resulting in a total of 60 feature stimuli for each SF version (LSF, HSF, and full spectrum, seeFigure 1). ...
Faces are perceived holistically, a phenomenon best illustrated when the processing of a face feature is affected by the other features. Here, the authors tested the hypothesis that the holistic perception of a face mainly relies on its low spatial frequencies. Holistic face perception was tested in two classical paradigms: the whole-part advantage (Experiment 1) and the composite face effect (Experiments 2-4). Holistic effects were equally large or larger for low-pass filtered faces as compared to full-spectrum faces and significantly larger than for high-pass filtered faces. The disproportionate composite effect found for low-pass filtered faces was not observed when holistic perception was disrupted by inversion (Experiment 3). Experiment 4 showed that the composite face effect was enhanced only for low spatial frequencies, but not for intermediate spatial frequencies known be critical for face recognition. These findings indicate that holistic face perception is largely supported by low spatial frequencies. They also suggest that holistic processing precedes the analysis of local features during face perception.
... However, the visual system may use different spatial frequency bands flexibly to solve a task, depending on the available information and the top-down control of the handling task [58]. Indeed, studies on face perception have shown that better performance in matching two stimuli was obtained when both stimuli were filtered to the same SF band, compared to when the two stimuli contained broadband or, even more noticeably, different SF bands [62,63]. This shows that, at least in certain tasks, limiting the processing of complex stimuli (such as faces and bodies) to given sources of information, as conveyed by one of the SF channels, might be advantageous. ...
... Furthermore, although human faces and body shapes are both biological stimuli that are relevant for social communication, their visual structure is inherently different and may trigger configural processing at different levels. In this regard, several authors have described a configural processing continuum in which different types of processing mechanisms can be distinguished, starting from part-based processing up to the holistic processing of the whole stimulus [16,63]. As addressed by Minnebusch and Daum [64], mechanisms for face and body perception may share the earlier stages of this continuum, namely, first-order relational information and structural information, while dissociations might take place at later stages, at the level of holistic processing. ...
Body inversion effects (BIEs) reflect the deployment of the configural processing of body stimuli. BIE modulates the activity of body-selective areas within both the dorsal and the ventral streams, which are tuned to low (LSF) or high spatial frequencies (HSF), respectively. The specific contribution of different bands to the configural processing of bodies along gender and posture dimensions, however, is still unclear. Seventy-two participants performed a delayed matching-to-sample paradigm in which upright and inverted bodies, differing for gender or posture, could be presented in their original intact form or in the LSF-or HSF-filtered version. In the gender discrimination task, participants' performance was enhanced by the presentation of HSF images. Conversely, for the posture discrimination task, a better performance was shown for either HSF or LSF images. Importantly, comparing the amount of BIE across spatial-frequency conditions, we found greater BIEs for HSF than LSF images in both tasks, indicating that configural body processing may be better supported by HSF information, which will bias processing in the ventral stream areas. Finally, the exploitation of HSF information for the configural processing of body postures was lower in individuals with higher autistic traits, likely reflecting a stronger reliance on the local processing of body-part details.
... The magnitudes of iconic memory ( 1 ) and baseline information maintenance ( 0 ) improvements were significantly correlated with CSF improvements (see Fig. S3). To better understand the transfer of training effect, we developed a simple predictive model of post-training iconic memory and baseline information maintenance based on imagecomputable object recognition models [19][20][21][22][23][24][25] , In particular, the posttraining iconic memory ( 1 ) and baseline information maintenance ( 0 ) were predicted by pre-training performance in the partial report paradigm, and pre-and post-training CSF (more details in Materials and Methods): ...
... In image-computable object recognition models [19][20][21][22][23][24][25] , the CSF serves as the front-end filter, and the total amount of signal-to-noise ratio is proportional to the integral of the CSF filtered image: ...
Iconic memory and short-term memory are not only crucial for perception and cognition, but also of great importance to mental health. Here, we first showed that both types of memory could be improved by improving limiting processes in visual processing through perceptual learning. Normal adults were trained in a contrast detection task for ten days, with their higher-order aberrations (HOA) corrected in real-time. We found that the training improved not only their contrast sensitivity function (CSF), but also their iconic memory and baseline information maintenance for short-term memory, and the relationship between memory and CSF improvements could be well-predicted by an observer model. These results suggest that training the limiting component of a cognitive task with visual perceptual learning could improve visual cognition. They may also provide an empirical foundation for new therapies to treat people with poor sensory memory.
... A multitude of methods have been used to determine the critical spatial frequencies involved in the identification of faces including selectively removing spatial frequency channels until identification is near impossible. These studies have indicated that spatial frequencies between 8 and 16 cycles per face are the most critical in recognition of faces (Bachmann, 1991;Costen, Parker, & Craw, 1994, 1996Fiorentini, Maffei, & Sandini, 1983;Ginsburg, 1978Ginsburg, , 1986Gold, Bennett, & Sekuler, 1999;Konorski & Petersik, 2003;Näsänen, 1999;Parker & Costen, 1999;Tieger & Ganz, 1979), though some suggest spatial frequencies of 25 cycles per face are crucial to recognition of faces (Hayes, Morrone, & Burr, 1986). ...
... This matching of spatial frequencies at learning and at test is more important for faces than objects and is similar for upright and inverted faces (Collin, Liu, Troje, McMullen, & Chaudhuri, 2004). Indeed, it is possible to recognize faces that do not contain the critical spatial frequencies at high levels of accuracy if they have been learned and are tested containing the same spatial frequencies (Konorski & Petersik, 2003). ...
Five minutes of processing the local features of a Navon letter causes a detriment in subsequent face-recognition performance (Macrae & Lewis, 2002). We hypothesize a perceptual after effect explanation of this effect in which face recognition is less accurate after adapting to high-spatial frequencies at high contrasts. Five experiments were conducted in which face-recognition performance was compared after processing high-contrast Navon stimuli. The standard recognition deficit was observed for processing the local features of Navon stimuli, but not if the stimuli were blurred (Experiment 1) or if they were of lower contrast (Experiment 2). A face-recognition deficit was observed after processing small, high-contrast letters equivalent to local processing of Navon letters (Experiment 3). Experiments 4 and 5 demonstrated that recognition of bandpass-filtered faces interacted with the type of Navon processing, in which the recognition of low-pass filtered faces was better following local rather than global processing. These results suggest that the Navon effect on subsequent face recognition is a perceptual phenomenon.
... The results were identical: When the participants matched face images that were filtered in the same way, no advantage of the middle band emerged. Most recently, Kornowski and Petersik (2003) have also provided evidence that the accuracy of face recognition varies primarily on the basis of the degree of congruency between comparison and test stimuli, rather than any particular range of SFs that might be included in the stimuli. They had participants learn faces that were high-passed, low-passed, or unfiltered and then had them recognize high-passed, low-passed, and unfiltered faces. ...
... One consistent difference between the experiments that support or do not support the middle-band hypothesis is that in one set (those supportive of a middle-band advantage) comparison stimuli are unfiltered, whereas in the second set (those not supportive of a middle-band advantage) comparison stimuli are filtered in the same way as test stimuli. To our knowledge, only Kornowski and Petersik (2003) have examined in detail conditions in which comparison stimuli are both filtered and unfiltered (but see Gold et al., 1999, p. 3551). However, because they examined only low-passed and high-passed conditions , their results do not bear directly on the question of whether middle frequencies might be advantageous in cases in which comparison stimuli are unfiltered. ...
Previous work has shown an advantage of middle spatial frequencies (SFs) in face recognition. However, a few recent studies have suggested that this advantage is reduced when comparison and test stimuli are spatially filtered in a similar way. In the present study, we used standard psychophysical methods, in combination with a match-to-sample task, to determine the SF thresholds for face matching under conditions in which: (1) comparison stimuli were unfiltered and (2) comparison stimuli were spatially filtered in the same way as test stimuli. In two experiments, we show that SFs closer to the middle band are sought out more in the former case than in the latter. These results are compatible with the idea that a middle band of SFs will be most useful for any visual task and that the breadth of this optimal middle band will vary depending on task characteristics.
... Lower spatial frequencies could affect outline identification more than higher spatial frequencies, and most of the information that is received by the eyes is from low spatial frequencies [23]. Because excellent retinal image contrast is also required under low spatial frequencies, in addition to higher cut-off spatial frequencies [24], 0-60 c/d of the spatial frequencies were chosen for the investigation in the present study. ...
In this study, the effects of intraocular lenses (IOLs) with different diopters (D) on chromatic aberration were investigated in human eye models, and the influences of the central thickness of IOLs on chromatic aberration were compared.
A Liou-Brennan-based IOL eye model was constructed using ZEMAX optical design software. Spherical IOLs with different diopters (AR40e, AMO Company, USA) were implanted; modulation transfer function (MTF) values at 3 mm of pupil diameter and from 0 to out-of-focus blur were collected and graphed.
MTF values, measured at 555 nm of monochromatic light under each spatial frequency, were significantly higher than the values measured at 470 to 650 nm of polychromatic light. The influences of chromatic aberration on MTF values decreased with the increase in IOL diopter when the spatial frequency was ≤12 c/d, while increased effects were observed when the spatial frequency was ≥15 c/d. The MTF values of each IOL eye model were significantly lower than the MTF values of the Liou-Brennan eye models when measured at 555 nm of monochromatic light and at 470 to 650 nm of polychromatic light. The MTF values were also found to be increased with the increase in IOL diopter.
With higher diopters of IOLs, the central thickness increased accordingly, which could have created increased chromatic aberration and decreased the retinal image quality. To improve the postoperative visual quality, IOLs with lower chromatic aberration should be selected for patients with short axial lengths.
... Models of spatial vision that employ the CSF as the front-end SF filter have been developed to account for human performance in a wide range of visual tasks, including letter identification [33,34] and face recognition [35], implicitly treating the CSF as the gain profile of the visual system in the spatial frequency space [36]. Although these models provided good accounts of human performance in many tasks, equating the gain profile of the channels according to the CSF of the observer may be problematic. ...
Sensitivity to luminance difference, or contrast sensitivity, is critical for animals to survive in and interact with the external world. The contrast sensitivity function (CSF), which measures visual sensitivity to spatial patterns over a wide range of spatial frequencies, provides a comprehensive characterization of the visual system. Despite its popularity and significance in both basic research and clinical practice, it hasn't been clear what determines the CSF and how the factors underlying the CSF change in different conditions. In the current study, we applied the external noise method and perceptual template model to a wide range of external noise and spatial frequency (SF) conditions, and evaluated how the various sources of observer inefficiency changed with SF and determined the limiting factors underlying the CSF. We found that only internal additive noise and template gain changed significantly with SF, while the transducer non-linearity and coefficient for multiplicative noise were constant. The 12-parameter model provided a very good account of all the data in the 200 tested conditions (86.5%, 86.2%, 89.5%, and 96.4% for the four subjects, respectively). Our results suggest a reconsideration of the popular spatial vision model that employs the CSF as the front-end filter and constant internal additive noise across spatial frequencies. The study will also be of interest to scientists and clinicians engaged in characterizing spatial vision deficits and/or developing rehabilitation methods to restore spatial vision in clinical populations.
... Models of spatial vision that employ the CSF as the front-end SF filter have been developed to account for human performance in a wide range of visual tasks, including letter identification [33,34] and face recognition [35], implicitly treating the CSF as the gain profile of the visual system in the spatial frequency space [36]. Although these models provided good accounts of human performance in many tasks, equating the gain profile of the channels according to the CSF of the observer may be problematic. ...
Sensitivity to luminance difference, or contrast sensitivity, is critical for animals to survive in and interact with the external world. The contrast sensitivity function (CSF), which measures visual sensitivity to spatial patterns over a wide range of spatial frequencies, provides a comprehensive characterization of the visual system. Despite its popularity and significance in both basic research and clinical practice, it hasn't been clear what determines the CSF and how the factors underlying the CSF change in different conditions. In the current study, we applied the external noise method and perceptual template model to a wide range of external noise and spatial frequency (SF) conditions, and evaluated how the various sources of observer inefficiency changed with SF and determined the limiting factors underlying the CSF. We found that only internal additive noise and template gain changed significantly with SF, while the transducer non-linearity and coefficient for multiplicative noise were constant. The 12-parameter model provided a very good account of all the data in the 200 tested conditions (86.5%, 86.2%, 89.5%, and 96.4% for the four subjects, respectively). Our results suggest a re-consideration of the popular spatial vision model that employs the CSF as the front-end filter and constant internal additive noise across spatial frequencies. The study will also be of interest to scientists and clinicians engaged in characterizing spatial vision deficits and/or developing rehabilitation methods to restore spatial vision in clinical populations.
... Several studies have reported the preferential role of the lowest band of frequencies (2–8 cpf) to be more important in the representation of a global percept of a face (Collishaw and Hole, 2000; Goffaux et al., 2003 Goffaux et al., , 2005 Goffaux, 2009; de Heering et al., 2008). It has also been reported that human observers are not able to utilize information in all the SF bands with equal efficiency and rely more on mid-band, rather than LSF or HSF (Gold et al., 1999; Kornowski and Petersik, 2003). The middle band of frequencies situated around 8–16 cpf, is reported to be important in identity recognition (e.g., Gold et al., 1999; Näsänen, 1999; Tanskanen et al., 2005), while the fine-tuned analysis of local details is based on higher ranges of SF (above 32 cpf; Goffaux and Rossion, 2006). ...
Research exploring the role of spatial frequencies in rapid stimulus detection and categorization report flexible reliance on specific spatial frequency (SF) bands. Here, through a set of behavioral and magnetoencephalography (MEG) experiments, we investigated the role of low spatial frequency (LSF) (<8 cycles/face) and high spatial frequency (HSF) (>25 cycles/face) information during the categorization of faces and places. Reaction time measures revealed significantly faster categorization of faces driven by LSF information, while rapid categorization of places was facilitated by HSF information. The MEG study showed significantly earlier latency of the M170 component for LSF faces compared to HSF faces. Moreover, the M170 amplitude was larger for LSF faces than for LSF places, whereas the reverse pattern was evident for HSF faces and places. These results suggest that SF modulates the processing of category specific information for faces and places.
... However, our findings point to more interesting avenues for further investigation into the nature of DP and face processing. It has also been reported that human observers are not able to utilize information in all the spatial frequency bands with equal efficiency and rely more on mid-band rather than low or high spatial frequency (Gold, Bennett, & Sekuler, 1999; Kornowski & Petersik, 2003). Through this study, we propose that efficient integration of LSF and HSF bands can enable efficient processing of faces, and a disruption in integrating information from these bands could impair the normal recognition of faces. ...
Developmental prosopagnosia (DP) is characterized by a selective deficit in face recognition despite normal cognitive and neurological functioning. Previous research has established configural processing deficits in DP subjects. Low spatial frequency (LSF) information subserves configural face processing. Using hybrid stimuli, here we examined the evolution of perceptual dynamics and integration of LSF information by DP subjects while they pointed to high spatial frequency (HSF) face targets. Permutation analysis revealed a 230-ms delay in LSF processing by DP subjects as compared to controls. This delayed processing is likely to contribute to the difficulties associated with face recognition in DP subjects and is reflective of their alleged reliance on local rather than global features in face perception. These results suggest that quick and efficient processing of LSF information is critical for the development of normal face perception.
... It has also been reported that human observers are not able to utilize information in all the spatial frequency bands with equal efficiency and rely more on mid-band rather than low or high spatial frequency (Gold, Bennett, & Sekuler, 1999;Kornowski & Petersik, 2003). Through this study, we propose that efficient integration of LSF and HSF bands can enable efficient processing of faces, and a disruption in integrating information from these bands could impair the normal recognition of faces. ...
... Since both configural and featural information can be extracted from LSF and HSF faces (Goffaux et al., 2005), it is not surprising that holistic processing-combining individual features into a "gestalt"-occurs equally for both LSF and HSF faces. In particular, given that a critical factor in successful face recognition is the overlap of spatial frequency bands between study and test stimuli (Boutet, Collin, & Faubert, 2003;Collin, Liu, Troje, McMullen, & Chaudhuri, 2004;Kornowski & Petersik, 2003;Liu, Collin, Rainville, & Chaudhuri, 2000), it is possible that holistic processing may occur for HSF only when both study and test faces contain this information. This does not mean that LSF and HSF information are processed by the same mechanisms or have the same relations with neural markers of holistic processing. ...
V. Goffaux and B. Rossion (2006) argued that holistic processing of faces is largely supported by low spatial frequencies (LSFs) but less so by high spatial frequencies (HSFs). We addressed this claim using a sequential matching task with face composites. Observers judged whether the top halves of aligned or misaligned composites were identical. We replicated the V. Goffaux and B. Rossion (2006) results, finding a greater alignment effect in accuracy for LSF compared with HSF faces on same trials. However, there was also a greater bias for responding "same" for HSF compared with LSF faces, indicating that the alignment effects arose from differential response biases. Crucially, comparable congruency effects found for LSF and HSF suggest that LSF and HSF faces are processed equally holistically. These results demonstrate that it is necessary to use measures that take response biases into account in order to fully understand the holistic nature of face processing.
... Whereas visual acuity reflects limits of spatial resolution, contrast-sensitivity function assesses spatial vision over a full range of spatial frequencies and is widely believed to reflect the overall gain of the visual system to visual input in different spatial frequencies. Models with CSF as the front-end spatial frequency filter can account for human performance in a wide range of visual tasks, including letter identification Chung, Levi, Legge, & Tjan, 2002) and face recognition (Kornowski & Petersik, 2003). Here, we assessed visual acuity and contrast-sensitivity functions of the amblyopic and fellow eyes of anisometropic amblyopes prior to and after intensive training in contrast detection either at a single spatial frequency near each individualÕs cut-off frequency on the CSF or over a range of spatial frequencies (i.e., repeated measures of CSF). ...
To evaluate the effects of perceptual learning on contrast-sensitivity function and visual acuity in adult observers with amblyopia, 23 anisometropic amblyopes with a mean age of 19.3 years were recruited and divided into three groups. Subjects in Group I were trained in grating detection in the amblyopic eye near pre-training cut-off spatial frequency. Group II received a training regimen of repeated contrast-sensitivity function measurements in the amblyopic eye. Group III received no training. We found that training substantially improved visual acuity and contrast-sensitivity functions in the amblyopic eyes of all the observers in Groups I and II, although no significant performance improvement was observed in Group III. For observers in Group I, performance improvements in the amblyopic eyes were broadly tuned in spatial frequency and generalized to the fellow eyes. The latter result was not found in Group II. In a few cases tested, improvements in visual acuity following training showed about 90% retention for at least 1 year. We concluded that the visual system of adult amblyopes might still retain substantial plasticity. Perceptual learning shows potential as a clinical tool for treating child and adult amblyopia.
... For instance, middle ranges of SFs may be most useful for face recognition (Na« sa« nen 1999; Parker and Costen 2001; Rolls et al 1987). Determining the useful scales of information for different tasks, especially the recognition of different classes of visual objects, has been the subject of much research (Bachmann 1991; Boutet et al 2003; Braje et al 1995; Bruner and Potter 1964; Collin 2003; Collin et al, in press, a; Collin et al, in press, b; Costen et al 1994 Costen et al , 1996 Fiorentini et al 1983; Ginsburg 1978; Gold et al 1999; Gosselin and Schyns 2001; Hayes et al 1986; Kornowski and Petersik 2003; Liu et al 2000; Marr 1982; Morrison and Schyns 2001; Na« sa« nen 1999; Olds and Engel 1998; Parker and Costen 2001; Rolls et al 1987; Schyns and Oliva 1997; Sergent and Bindra 1981; Tieger and Ganz 1979; Uttal et al 1997; Vannucci et al 2001; Vuilleumier et al 2003; Wenger and Townsend 2000). If certain ranges of SFs are most useful for recognising particular object classes, then these optimal SF ranges will likely vary depending on the kinds of information available in the stimuli and the demands of the task. ...
In an attempt to understand how low-level visual information contributes to object categorisation, previous studies have examined the effects of spatially filtering images on object recognition at different levels of abstraction. Here, the quantitative thresholds for object categorisation at the basic and subordinate levels are determined by using a combination of the method of adjustment and a match-to-sample method. Participants were asked to adjust the cut-off of either a low-pass or high-pass filter applied to a target image until they reached the threshold at which they could match the target image to one of six simultaneously presented category names. This allowed more quantitative analysis of the spatial frequencies necessary for recognition than previous studies. Results indicate that a more central range of low spatial frequencies is necessary for subordinate categorisation than basic, though the difference is small, at about 0.25 octaves. Conversely, there was no effect of categorisation level on high-pass thresholds.
... Many researchers have suggested that the contrast sensitivity function (CSF), which assesses spatial vision over a wide range of spatial frequencies and contrast levels, may be a better tool for detecting and diagnosing deficits in spatial vision (Della Sala, Bertoni, Somazzi, Stubbe, & Wilkins, 1985;Hess, 1979;Hess & Howell, 1977;Jindra & Zemon, 1989;Marmor, 1981;Marmor, 1986;Marmor & Gawande, 1988;Montes-Mico & Ferrer-Blasco, 2001;Wolkstein, Atkin, & Bodis-Wollner, 1980;Woo & Dalziel, 1981;Yenice et al., 2006). Models using the CSF as the front-end spatial frequency filter can account for normal human performance in a wide range of visual tasks, including letter identification (Pelli, Levi, & Chung, 2004) and face recognition (Kornowski & Petersik, 2003). In a recent analysis of 427 adults with amblyopia or with risk factors for amblyopia, McKee, Levi, and Movshon (2003) concluded that two orthogonal dimensions are needed to account for the variations in amblyopic visual performance: one relates to visual acuity measures (optotype, Vernier, and grating acuity) and the other relates to contrast sensitivity measures (Pelli-Robson and edge contrast sensitivity). ...
To evaluate residual spatial vision deficits in treated amblyopia, we recruited five clinically treated amblyopes (mean age=10.6 years). Contrast sensitivity functions (CSF) in both the previously amblyopic eyes (pAE; visual acuity=0.944+/-0.019 MAR) and fellow eyes (pFE; visual acuity=0.936+/-0.021 MAR) were measured using a standard psychophysical procedure for all the subjects. The results indicated that the treated amblyopes remained deficient in spatial vision, especially at high spatial frequencies, although their Snellen visual acuity had become normal in the pAEs. To identify the mechanisms underlying spatial vision deficits of treated amblyopes, threshold vs external noise contrast (TvC) functions--the signal contrast necessary for the subject to maintain a threshold performance level in varying amounts of external noise ("TV snow")--were measured in both eyes of four of the subjects in a sine-wave grating detection task at several spatial frequencies. Two mechanisms of amblyopia were identified: increased internal noise at low to medium spatial frequencies, and both increased internal noise and increased impact of external noise at high spatial frequencies. We suggest that, in addition to visual acuity, other tests of spatial vision (e.g., CSF, TvC) should be used to assess treatment outcomes of amblyopia therapies. Training in intermediate and high spatial frequencies may be necessary to fully recover spatial vision in amblyopia in addition to the occlusion therapy.
While the dependence of face identification on the level of pixelation-transform of the images of faces has been well studied, similar research on face-based trait perception is underdeveloped. Because depiction formats used for hiding individual identity in visual media and evidential material recorded by surveillance cameras often consist of pixelized images, knowing the effects of pixelation on person perception has practical relevance. Here, the results of two experiments are presented showing the effect of facial image pixelation on the perception of criminality, trustworthiness, and suggestibility. It appears that individuals (N = 46, M age = 21.5 yr., SD = 3.1 for criminality ratings; N = 94, M age = 27.4 yr., SD = 10.1 for other ratings) have the ability to discriminate between facial cues indicative of these perceived traits from the coarse level of image pixelation (10-12 pixels per face horizontally) and that the discriminability increases with a decrease in the coarseness of pixelation. Perceived criminality and tnistworthiness appear to be better carried by the pixelized images than perceived suggestibility.
To consider factors relevant to the design of wavefront-aberration-based customized ablations.
Review.
Ablations that seek to eliminate all wavefront aberrations, both second- and higher-order, may not be optimal for all patients. This is particularly the case for presbyopes. Their main requirement will normally be for extended binocular depth-of-focus to yield adequate distance and near vision with good retinal contrast at lower spatial frequencies, rather than the highest levels of acuity and modulation transfer function at a single distance. For many presbyopes, this can be achieved by aiming for monovision correction or low myopic astigmatism, with reasonable but not necessarily complete correction of higher-order aberrations. This compromise allows a range of everyday tasks to be carried out, including face recognition and reading.
The targeted correction of wavefront aberration should take into account the visual needs and preferences of the individual patient.
The present study examined the role of high-spatial frequency information in early face processing, as indexed by the N170 face-sensitive ERP component. Participants detected 4 versions of famous faces, including full spectrum faces, and bandpass filtered faces containing predominantly high-spatial frequencies, low-spatial frequencies or both. The power spectra of all stimuli were balanced by superimposing the faces onto a visual noise background that included the spatial frequency information that was missing in filtered faces, e.g., high-spatial frequency faces were presented on a high- and low-spatial frequency background. An additional condition comprising of filtered visual noise only was also created to ensure that any observed effects were related to the processing of faces and not simply due to variations between spatial frequency information. Both behavioral and electrophysiological results replicated previous findings of a low-spatial frequency advantage for face processing. However, our results also show that faces containing both high and low-spatial frequency information are detected faster and more accurately than faces containing predominantly low-spatial frequencies. Furthermore, this advantage occurred with an enhanced amplitude of the N170. Together, these findings refute the suggestion that high-spatial frequencies are redundant in face perception.
A great deal of work has been devoted to the question of which spatial frequencies, if any, are optimal for various visual tasks, such as face and object recognition. However, to date these studies have all been carried out with stimuli set against a uniform background. It is possible that this type of stimulus does not produce ecologically valid results. The natural world in which visual tasks normally take place involves a great deal of luminance variation and distracting visual structure, which may alter the spatial frequencies necessary for a task. We conducted two experiments that examined the effects of image background on the spatial-frequency thresholds (50% maximum of a low-pass or high-pass Butterworth filter) for face recognition by the psychophysical methods of adjustment and constant stimuli. In both experiments we found no significant difference in spatial-frequency thresholds between uniform-grey backgrounds and natural-scene backgrounds, and only minor differences between uniform-grey backgrounds and fractal noise backgrounds. This suggests that results obtained with uniform backgrounds are ecologically valid and that background effects, if they exist, are small.
The effects of spatial frequency overlap between pairs of low-pass versus high-pass images on face recognition and matching were examined in 6 experiments. Overlap was defined as the range of spatial frequencies shared by a pair of filtered images. This factor was manipulated by processing image pairs with high-pass/low-pass filter pairs whose 50% cutoff points varied in their separation from one another. The effects of the center frequency of filter pairs were also investigated. In general, performance improved with greater overlap and higher center frequency. In control conditions, the image pairs were processed with identical filters and thus had complete overlap. Even severely filtered low-pass or high-pass images in these conditions produced superior performance. These results suggest that face recognition is more strongly affected by spatial frequency overlap than by the frequency content of the images. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
If face images are degraded by block averaging, there is a nonlinear decline in recognition accuracy as block size increases,
suggesting that identification requires a critical minimum range of object spatial frequencies. The identification of faces
was measured with equivalent Fourier low-pass filtering and block averaging preserving the same information and with high-pass
transformations. In Experiment 1, accuracy declined and response time increased in a significant nonlinear manner in all cases
as the spatial-frequency range was reduced. However, it did so at a faster rate for the quantized and high-passed images.
A second experiment controlled for the differences in the contrast of the high-pass faces and found a reduced but significant
and nonlinear decline in performance as the spatial-frequency range was reduced. These data suggest that face identification
is preferentially supported by a band of spatial frequencies of approximately 8-16 cycles per face; contrast or line-based
explanations were found to be inadequate. The data are discussed in terms of current models of face identification.
1. To analyze the selectivity and the sparseness of firing to visual stimuli of single neurons in the primate temporal cortical visual area, neuronal responses were measured to a set of 68 visual stimuli in macaques performing a visual fixation task. The population of neurons analyzed had responses that occurred primarily to faces. The stimuli included 23 faces, and 45 nonface images of real-world scenes, so that the function of this brain region could be analyzed when it was processing natural scenes. 2. The neurons were selected to meet the previously used criteria of face selectivity by responding more than twice as much to the optimal face as to the optimal nonface stimulus in the set. Application of information theoretic analyses to the responses of these neurons confirmed that their responses contained much more information about which of 20 face stimuli had been seen (on average 0.4 bits) than about which (of 20) nonface stimuli had been seen (on average 0.07 bits). 3. The sparseness of the representation of a scene or object provided by each of these neurons (which can be thought of as the proportion of stimuli to which the neuron responds, and which is fundamental to understanding the network operation of the system) can be defined as [formula: see text] where ri is the firing rate to the ith stimulus in the set of n stimuli. The sparseness has a maximal value of 1.0. It was found that the sparseness of the representation of the 68 stimuli by each neuron had an average across all neurons of 0.65. This indicates a rather distributed representation. 4. If the spontaneous firing rate was subtracted from the firing rate of the neuron to each stimulus, so that the changes of firing rate, i.e., the responses of the neurons, were used in the sparseness calculation, then the "response sparseness" had a lower value, with a mean of 0.33 for the population of neurons, or 0.60 if calculated over the set of faces. 5. Multidimensional scaling to produce a stimulus space represented by this population of neurons showed that the different faces were well separated in the space created, whereas the different nonface stimuli were grouped together in the space. 6. The information analyses and multidimensional scaling provided evidence that what was made explicit in the responses of these neurons was information about which face had been seen.(ABSTRACT TRUNCATED AT 400 WORDS)
If face images are degraded by block averaging, there is a nonlinear decline in recognition accuracy as block size increases, suggesting that identification requires a critical minimum range of object spatial frequencies. The identification of faces was measured with equivalent Fourier low-pass filtering and block averaging preserving the same information and with high-pass transformations. In Experiment 1, accuracy declined and response time increased in a significant nonlinear manner in all cases as the spatial-frequency range was reduced. However, it did so at a faster rate for the quantized and high-passed images. A second experiment controlled for the differences in the contrast of the high-pass faces and found a reduced but significant and nonlinear decline in performance as the spatial-frequency range was reduced. These data suggest that face identification is preferentially supported by a band of spatial frequencies of approximately 8-16 cycles per face; contrast or line-based explanations were found to be inadequate. The data are discussed in terms of current models of face identification.
The role of spatial scales (or spatial frequencies) in the processing of faces, objects, and scenes has recently seen a surge of research activity. In this review, we will critically examine two main theories of scale usage. The fixed theory proposes that spatial scales are used in a fixed, perceptually determined order (coarse to fine). The flexible theory suggests instead that usage of spatial scales is flexible, depending on the requirements of visual information for the categorization task at hand. The implications of the theories are examined for face, object, and scene categorization, attention, perception, and representation.
We studied the effect on false alarms and correct detections in taste threshold determinations caused by variations in signal presentation probabilities. A modified method of constant stimuli was used. Results indicate that a simple threshold theory with correction for guessing cannot account for these data. A more sophisticated threshold theory can do as well as signal detectability theory. (22 ref.) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
this paper (except the resliced images labeled "Axial" in Fig. 2). The brain images at the left show in color the voxels that produced a significantly higher MR signal intensity (based on smoothed data) during the epochs containing faces than during those containing objects (1a) and vice versa (1b) for 1 of the 12 slices scanned. These significance images (see color key at right for this and all figures in this paper) are overlaid on a T1-weighted anatomical image of the same slice. Most of the other 11 slices showed no voxels that reached significance at the p , 10
The visual information that comprises a face is changing constantly. Faces age, features are altered with expression, eye-glasses are put on, and view-point and distance change almost moment to moment. Despite the variety of visual input connected with any single face, we are nearly always able to recognize faces we have seen before. In the study reported here we are interested in recognition of faces that have been spatially transformed. The specific question addressed in this paper relates to the information people use to recognize faces that are observed and tested under different spatial frequency presentations.
To facilitate visual search of complex scenes, information arising from recently attended locations is subject to a selective inhibition in processing known as inhibition of return (IOR). Although the mechanisms of IOR remain unresolved, both motor and perceptual influences have been proposed based on reaction time (RT) studies. Here we report the results of two reflexive cuing studies in which signal detection methodology was employed to directly examine the effects of IOR on perception. IOR was found to be associated with a significant reduction in the accuracy of target discriminations at recently attended locations. Further, these effects of IOR on response accuracy were independent of whether emphasis was placed on the speed of responding. These results provide the first direct evidence that IOR can affect the perceptual quality of visual processing.
Because studies employing d′ and η are based on the theory of signal detectability, the theory is reviewed in sufficient detail for the purposes of definition. The efficiency, η, is defined as the ratio of the energy required by an ideal receiver to the energy required by a receiver under study when the performance of the two is the same. The measure d′ is that value of (2E/N 0 ) 1 2 necessary for the ideal receiver to match the performance of the receiver under study, where E is the energy of the signal, and N 0 is the noise power per unit band width. The measure is extended to include the recognizability of two signals. Every set of signals is described by a Euclidean space in which distances are the square roots of the energy of the difference signal, (E Δ ) 1 2 . The unit of measure is the square root of one‐half of the noise power per unit band width (N 0 /2) 1 2 .
The main objective of this book is to integrate the methods of experimental psychology with content. The argument is that methods cannot be learned independently of content. The methods are explained in the context of fundamental questions about human behavior. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Detection Theory is an introduction to one of the most important tools for analysis of data where choices must be made and performance is not perfect. Originally developed for evaluation of electronic detection, detection theory was adopted by psychologists as a way to understand sensory decision making, then embraced by students of human memory. It has since been utilized in areas as diverse as animal behavior and X-ray diagnosis. This book covers the basic principles of detection theory, with separate initial chapters on measuring detection and evaluating decision criteria. Some other features include: complete tools for application, including flowcharts, tables, pointers, and software;. student-friendly language;. complete coverage of content area, including both one-dimensional and multidimensional models;. separate, systematic coverage of sensitivity and response bias measurement;. integrated treatment of threshold and nonparametric approaches;. an organized, tutorial level introduction to multidimensional detection theory;. popular discrimination paradigms presented as applications of multidimensional detection theory; and. a new chapter on ideal observers and an updated chapter on adaptive threshold measurement. This up-to-date summary of signal detection theory is both a self-contained reference work for users and a readable text for graduate students and other researchers learning the material either in courses or on their own. © 2005 by Lawrence Erlbaum Associates, Inc. All rights reserved.
The spatial frequencies most relied upon by subjects in a recall task for face recognition were found to lie in the midfrequency
range. A linear systems analysis model cannot account for these masking data in terms of retinocortical processing limitations
alone. In order to account for the greater disruption of the face recognition task by masks in the range of 2.2 cycles/deg,
the existence of unequal filtering of spatial frequency components must be recognized. This unequal filtering may occur either
during memory deposition or retrieval of the input stimulus in the recall task or at any time in between.
To better understand how the visual system makes use of information across spatial scales when identifying different kinds of complex patterns, we measured human and ideal contrast identification thresholds to estimate identification efficiency for 1- and 2-octave wide band-pass filtered letters and faces embedded in 2-D dynamic Gaussian noise. Varying stimulus center frequency from 1 to 70 c/object had different effects on letter and face identification efficiency. In the 2-octave conditions, identification efficiencies decreased by 0.25–0.5 log units for letters and 0.5–1.2 log units for faces as center frequency increased from 6.2 to 49.5 c/object, but only letters were identifiable at center frequencies below 6.2 c/object. In the 1-octave conditions, letter identification efficiencies increased by about 0.5 log units as center frequency increased from 1.1 to 2.2 c/object, and were nearly constant from 2.2 to 35 c/object. Letters were unidentifiable by human observers at 70 c/object. Surprisingly, face identification was impossible for human observers at all center frequencies except 8.8 c/object for one observer, and 8.8 and 17.5 c/object for a second observer. Ideal observer thresholds were obtained for both letters and faces in all conditions, so information was always available to perform the task. Thus, the failure to identify faces reflects constraints on visual processing rather than a lack of stimulus information. Selective spatial sampling may account for some of the differences between letter and face identification efficiencies.
A study is reported in which the significance for vision of low- and high-spatial-frequency components of photographic positive and negative images was investigated by measuring recognition of bandpass-filtered photographs of faces. The results show that a 1.5 octave bandpass-filtered image contains sufficient visual information for good recognition performance, provided the filter is centred close to 20 cycles facewidth-1. At low spatial frequencies negatives are more difficult to recognize than positives, but at high spatial frequencies there is no difference in recognition, implying that it is the low-frequency components of negatives which present difficulties for the visual system.
Based upon perceptual studies, the present hypothesis was that different ranges of spatial-frequency information constitute different sources of information for recognition memory. In Experiment 1, 40 subjects were tested with sets of focused and unfocused pictures as inspection and test stimuli. In addition to reporting whether each test picture was believed to be a member of the inspection set or a novel picture, each subject was allowed to adjust the contrast of the stimulus until such a judgment could be made. In Experiment 2, subjects made similar judgments when inspection or test stimuli were flickered (perceptually enhancing low spatial frequencies) or unflickered. Results from both studies were consistent with the experimental hypothesis. Other studies were reviewed, which, together with the present data, lend converging evidence to the spatial-frequency hypothesis.
The relevance of low and high spatial-frequency information for the recognition of photographs of faces has been investigated by testing recognition of faces that have been either low-pass (LP) or high-pass (HP) filtered in the spatial-frequency domain. The highest resolvable spatial frequency was set at 15 cycles per face width (cycles fw-1). Recognition was much less accurate for images that contained only the low spatial frequencies (up to 5 cycles fw-1) than for images that contained only spatial frequencies higher than 5 cycles fw-1. For faces HP filtered above 8 cycles fw-1, recognition was almost as accurate as for faces LP filtered below 8 cycles fw-1, although the energy content of the latter greatly exceeded that of the former. These findings show that information conveyed by the higher spatial frequencies is not redundant. Rather, it is sufficient by itself to ensure recognition.
A new contrast sensitivity vision chart has been tested and compared to an automated video-based vision tester on 83 observers whose ages ranged from 9 to 75 years. Good agreement was found between the contrast sensitivity measurements obtained from the vision chart and the automated tester for similar population and age variations. These results suggest that vision test charts can be developed to provide useful contrast sensitivity psychometric functions and yet be as simple to use as present eye charts.
It has recently become apparent that if face images are degraded by spatial quantisation, or block averaging, there is a nonlinear acceleration of the decline in accuracy of recognition as block size increases. This suggests recognition requires a critical minimum range of object spatial frequencies. Two experiments were performed to clarify the phenomenon. In experiment 1, the speed and accuracy of recognition for six frontoparallel photographs of faces were measured. After familiarisation training sessions, the images were shown for 100 ms with 11, 21, and 42 pixels per face, horizontally measured. Transformations calculated to remove the same range of spatial frequencies were performed by means of quantisation, a Fourier low-pass filter, and Gaussian blurring. Although accuracy declined and speed increased in a significant, nonlinear manner in all cases as the image quality was reduced, it did so at a faster rate for the quantised images. In experiment 2, faces rated as being typical were shown at 9, 12, 23, and 45 pixels per face and with appropriate Fourier low-pass versions. The nonlinear decline was confirmed and it was shown that it could not be attributed to a ceiling effect. A further condition allowed quantised and Fourier low-pass conditions to be compared with an unstructured-noise condition of equal strength to that of the quantised images. These gave comparable, but slightly less impaired, recognition than the quantised images. It can be inferred from these results that the removal of a critical range of at least 8-16 cycles per face of information explains the step decline in recognition seen with quantised images. However, the decline found with quantised images is reinforced by internal masking from pixelisation.
The purpose of the study was to find out what spatial frequency information human observers use in the recognition of face images. Signal-to-noise ratio thresholds for the recognition of facial images were measured as a function of the centre spatial frequency of narrow-band additive spatial noise. The relative sensitivity of recognition to different spatial frequencies was derived from these results. The maximum sensitivity was found at 8-13 c/face width and the bandwidth was just under two octaves. Qualitatively similar results were obtained with stimuli in which Fourier phase was randomised within a narrow band of different centre spatial frequencies. This resulted in a considerable increase of energy threshold around 8 c/face width and less elsewhere. Further, contrast energy thresholds were measured as a function of the centre spatial frequency of band-pass filtered face images. As a function of object spatial frequency (c/face width), energy threshold first decreased and then increased. The lowest energy thresholds found around 10 c/face width were lower than the energy threshold for unfiltered images. This is what one would expect if face recognition is narrow-band, since band-pass filtered images of optimal centre spatial frequency do not contain unused contrast energy at low and high spatial frequencies. In conclusion, the results suggest that the recognition of facial images is tuned to a relatively narrow band (< 2 octaves) of mid object spatial frequencies.
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