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Breaking continuous flash suppression (b-CFS) experimental paradigm. (A) breaking Continuous Flash Suppression (b-CFS) task in Experiment 1. Observers reported the orientation of the grating using the appropriate keyboard keys as soon as it emerged from interocular suppression induced by a dynamic Mondrian patterns flashed in the other eye at 10 Hz. (B) b-CFS task in Experiment 2. Observers reported the location of the grating as soon as it emerged from interocular suppression.
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Monetary value enhances visual perception and attention and boosts activity in the primary visual cortex, however, it is still unclear whether monetary value can modulate the conscious access to rewarding stimuli. Here we investigate this issue by employing a breaking continuous flash suppression (b-CFS) paradigm. We measured suppression durations...
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... The spatial phase of the Gabor stimulus on each trial was randomly selected from the range of 0°to 360°. To remove the Gabor stimulus from visual awareness, we presented a series of high-contrast colored Mondrian-like masks (8.3°× 8.3°) flashing at 10 Hz (i.e., CFS) to subjects' dominant eye while the Gabor stimulus was presented to the nondominant eye ( Figure 1C) (e.g., Lunghi & Pooresmaeili, 2023;Mei, Dong, Dong, & Bao, 2015;Veto, Schütz, & Einhäuser, 2018). We used a mirror stereoscope to implement the presentation of the dichoptic stimuli. ...
The visual system often undergoes a relatively stable perception even in a noisy visual environment. This crucial function was reflected in a visual perception phenomenon—serial dependence, in which recent stimulus history systematically biases current visual decisions. Although serial dependence effects have been revealed in numerous studies, few studies examined whether serial dependence would require visual awareness. By using the continuous flash suppression (CFS) technique to render grating stimuli invisible, we investigated whether serial dependence effects could emerge at the unconscious levels. In an orientation adjustment task, subjects viewed a randomly oriented grating and reported their orientation perception via an adjustment response. Subjects performed a series of three type trial pairs. The first two trial pairs, in which subjects were instructed to make a response or no response toward the first trial of the pairs, respectively, were used to measure serial dependence at the conscious levels; the third trial pair, in which the grating stimulus in the first trial of the pair was masked by a CFS stimulus, was used to measure the serial dependence at the unconscious levels. One-back serial dependence effects for the second trial of the pairs were evaluated. We found significant serial dependence effects at the conscious levels, whether absence (Experiment 1) or presence (Experiment 2) of CFS stimuli, but failed to find the effects at the unconscious levels, corroborating the view that serial dependence requires visual awareness.
... Elevated arousal levels accompany a wide variety of emotions that may yield different perceptual effects. For example, percepts associated with monetary reward tend to break suppression faster (Lunghi & Pooresmaeili, 2023), whereas those associated with monetary loss tend to be suppressed (Wilbertz et al., 2014); arguably, both monetary gains and losses entail physiological arousal. ...
Fear and disgust have been associated with opposite influences on visual processing, even though both constitute negative emotions that motivate avoidance behavior and entail increased arousal. In the current study, we hypothesized that (a) homeostatic relevance modulates early stages of visual processing, (b) through widespread physiological responses, and that (c) the direction of these modulations depends on whether an emotion calls for immediate regulatory behavior or not. Specifically, we expected that increased arousal should facilitate the detection of fear-related stimuli, and inhibit the detection of disgust-related stimuli. These hypotheses were tested in two preregistered experiments (data collected in 2022, total N = 120, ethnically homogeneous Polish sample). Using a novel, response bias-free version of the breaking continuous flash suppression paradigm, we examined localization and discrimination of fear- and disgust-conditioned stimuli at individually determined perceptual thresholds. Our first hypothesis was confirmed: fear-conditioned stimuli were detected and discriminated better than neutral stimuli, and the magnitude of conditioning-related perceptual preference was related to arousal during conditioning acquisition. In contrast with our second hypothesis, perceptual access to disgust-conditioned stimuli was not diminished. Exploratory analyses suggest that discrimination of disgust-conditioned stimuli was also enhanced, although these effects appeared weaker than those evoked by fear conditioning. The current study strengthens previous evidence for facilitated perception of threatening objects and shows for the first time that stimuli evoking disgust might also gain preferential access to awareness. The results imply that homeostatically relevant stimuli are prioritized by the visual system and that this preference is grounded in the underlying arousal levels.
When the eyes view separate and incompatible images, the brain suppresses one image and promotes the other into visual awareness. Periods of interocular suppression can be prolonged during continuous flash suppression (CFS) – when one eye views a static ‘target’ while the other views a complex dynamic stimulus. Measuring the time needed for a suppressed image to break CFS (bCFS) has been widely used to investigate unconscious processing, and the results have generated controversy regarding the scope of visual processing without awareness. Here, we address this controversy with a new ‘CFS tracking’ paradigm (tCFS) in which the suppressed monocular target steadily increases in contrast until breaking into awareness (as in bCFS) after which it decreases until it again disappears (reCFS), with this cycle continuing for many reversals. Unlike bCFS, tCFS provides a measure of suppression depth by quantifying the difference between breakthrough and suppression thresholds. tCFS confirms that (i) breakthrough thresholds indeed differ across target types (e.g. faces vs gratings, as bCFS has shown) – but (ii) suppression depth does not vary across target types. Once the breakthrough contrast is reached for a given stimulus, all stimuli require a strikingly uniform reduction in contrast to reach the corresponding suppression threshold. This uniform suppression depth points to a single mechanism of CFS suppression, one that likely occurs early in visual processing because suppression depth was not modulated by target salience or complexity. More fundamentally, it shows that variations in bCFS thresholds alone are insufficient for inferring whether the barrier to achieving awareness exerted by interocular suppression is weaker for some categories of visual stimuli compared to others.
When the eyes view separate and incompatible images, the brain suppresses one image and promotes the other into visual awareness. Periods of interocular suppression can be prolonged during continuous flash suppression (CFS) – when one eye views a static ‘target’ while the other views a complex dynamic stimulus. Measuring the time needed for a suppressed image to break CFS (bCFS) has been widely used to investigate unconscious processing, and the results have generated controversy regarding the scope of visual processing without awareness. Here, we address this controversy with a new ‘CFS tracking’ paradigm (tCFS) in which the suppressed monocular target steadily increases in contrast until breaking into awareness (as in bCFS) after which it decreases until it again disappears (reCFS), with this cycle continuing for many reversals. Unlike bCFS, tCFS provides a measure of suppression depth by quantifying the difference between breakthrough and suppression thresholds. tCFS confirms that (i) breakthrough thresholds indeed differ across target types (e.g. faces vs gratings, as bCFS has shown) – but (ii) suppression depth does not vary across target types. Once the breakthrough contrast is reached for a given stimulus, all stimuli require a strikingly uniform reduction in contrast to reach the corresponding suppression threshold. This uniform suppression depth points to a single mechanism of CFS suppression, one that likely occurs early in visual processing because suppression depth was not modulated by target salience or complexity. More fundamentally, it shows that variations in bCFS thresholds alone are insufficient for inferring whether the barrier to achieving awareness exerted by interocular suppression is weaker for some categories of visual stimuli compared to others.
When the eyes view separate and incompatible images, the brain suppresses one image and promotes the other into visual awareness. Periods of interocular suppression can be prolonged during continuous flash suppression (CFS) - when one eye views a static ‘target’ while the other views a complex dynamic stimulus. Measuring the time needed for a suppressed image to break CFS (bCFS) has been widely used to investigate unconscious processing, and the results have generated controversy regarding the scope of visual processing without awareness. Here, we address this controversy with a new ‘CFS tracking’ paradigm (tCFS) in which the suppressed monocular target steadily increases in contrast until breaking into awareness (as in bCFS) after which it decreases until it again disappears (reCFS), with this cycle continuing for many reversals. Unlike bCFS, tCFS provides a measure of suppression depth by quantifying the difference between breakthrough and suppression thresholds. tCFS confirms that: (i) breakthrough thresholds indeed differ across target types (e.g., faces vs gratings, as bCFS has shown) – but (ii) suppression depth does not vary across target types. Once the breakthrough contrast is reached for a given stimulus, all stimuli require a strikingly uniform reduction in contrast to reach the corresponding suppression threshold. This uniform suppression depth points to a single mechanism of CFS suppression, one that likely occurs early in visual processing that is not modulated by target salience or complexity. More fundamentally, it shows that variations in breakthrough thresholds alone are insufficient for inferring unconscious or preferential processing of given image categories.
Research on unconscious vision has proliferated recently, often employing the continuous flash suppression (CFS) method in which flicker in one eye suppresses the other eye’s image from awareness. That image is strengthened progressively until it breaks into visibility. Low breakthrough thresholds are claimed to indicate unconscious processing during suppression. We introduce a method that quantifies breakthrough and also suppression thresholds, thus providing a lower bound missing from previous CFS research. Comparing various image types, including those claimed to undergo unconscious processing, all images show equal suppression when both thresholds are measured. We thus find no evidence of differential unconscious processing and conclude reliance on breakthrough thresholds is misleading without considering suppression thresholds and leads to spurious claims about unconscious processing.
Reward value and selective attention both enhance the representation of sensory stimuli at the earliest stages of processing. It is still debated whether and how reward-driven and attentional mechanisms interact to influence perception. Here we ask whether the interaction between reward value and selective attention depends on the sensory modality through which the reward information is conveyed. Human participants first learned the reward value of uni-modal visual and auditory stimuli during a conditioning phase. Subsequently, they performed a target detection task on bimodal stimuli containing a previously rewarded stimulus in one, both, or neither of the modalities. Additionally, participants were required to focus their attention on one side and only report targets on the attended side. Our results showed a strong modulation of visual and auditory event-related potentials (ERPs) by spatial attention. We found no main effect of reward value but importantly an interaction effect was found as the strength of attentional modulation of the ERPs was significantly affected by the reward value. When reward effects were inspected separately with respect to each modality, auditory value-driven modulation of attention was found to dominate the ERP effects whereas visual reward value on its own led to no effect, likely due to its interference with the target processing. These results inspire a two-stage model where first the salience of a high reward stimulus is enhanced on a local priority map specific to each sensory modality, and at a second stage reward value and top-down attentional mechanisms are integrated across sensory modalities to affect perception.
