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Lanfranco RC, Rabagliati H, Carmel D. The importance of awareness in face processing: A critical review of interocular suppression studies. Behav Brain Res 2023; 437:114116. [PMID: 36113728 DOI: 10.1016/j.bbr.2022.114116] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 08/15/2022] [Accepted: 09/12/2022] [Indexed: 10/14/2022]
Abstract
Human faces convey essential information for understanding others' mental states and intentions. The importance of faces in social interaction has prompted suggestions that some relevant facial features such as configural information, emotional expression, and gaze direction may promote preferential access to awareness. This evidence has predominantly come from interocular suppression studies, with the most common method being the Breaking Continuous Flash Suppression (bCFS) procedure, which measures the time it takes different stimuli to overcome interocular suppression. However, the procedures employed in such studies suffer from multiple methodological limitations. For example, they are unable to disentangle detection from identification processes, their results may be confounded by participants' response bias and decision criteria, they typically use small stimulus sets, and some of their results attributed to detecting high-level facial features (e.g., emotional expression) may be confounded by differences in low-level visual features (e.g., contrast, spatial frequency). In this article, we review the evidence from the bCFS procedure on whether relevant facial features promote access to awareness, discuss the main limitations of this very popular method, and propose strategies to address these issues.
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Affiliation(s)
- Renzo C Lanfranco
- Department of Psychology, University of Edinburgh, Edinburgh, United Kingdom; Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
| | - Hugh Rabagliati
- Department of Psychology, University of Edinburgh, Edinburgh, United Kingdom
| | - David Carmel
- Department of Psychology, University of Edinburgh, Edinburgh, United Kingdom; School of Psychology, Victoria University of Wellington, Wellington, New Zealand.
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2
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CFS-crafter: An open-source tool for creating and analyzing images for continuous flash suppression experiments. Behav Res Methods 2022:10.3758/s13428-022-01903-7. [PMID: 35794414 DOI: 10.3758/s13428-022-01903-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2022] [Indexed: 11/08/2022]
Abstract
Continuous flash suppression (CFS) is a popular masking technique used to manipulate visual awareness. By presenting a rapidly changing stimulus to one eye (the 'mask'), a static image viewed by the other (the 'target') may remain invisible for many seconds. This effectiveness affords a means to assess unconscious visual processing, leading to the widespread use of CFS in several basic and clinical sciences. However, the lack of principled stimulus selection has impeded generalization of conclusions across studies, as the strength of interocular suppression is dependent on the spatiotemporal properties of the CFS mask and target. To address this, we created CFS-crafter, a point-and-click, open-source tool for creating carefully controlled CFS stimuli. The CFS-crafter provides a streamlined workflow to create, modify, and analyze mask and target stimuli, requiring only a rudimentary understanding of image processing that is well supported by help files in the application. Users can create CFS masks ranging from classic Mondrian patterns to those comprising objects or faces, or they can create, upload, and analyze their own images. Mask and target images can be custom-designed using image-processing operations performed in the frequency domain, including phase-scrambling and spatial/temporal/orientation filtering. By providing the means for the customization and analysis of CFS stimuli, the CFS-crafter offers controlled creation, analysis, and cross-study comparison. Thus, the CFS-crafter-with its easy-to-use image processing functionality-should facilitate the creation of visual conditions that allow a principled assessment of hypotheses about visual processing outside of awareness.
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3
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A method for studying unconscious motion processing based on the camouflage principle. ACTA PSYCHOLOGICA SINICA 2022. [DOI: 10.3724/sp.j.1041.2022.00725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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4
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Abstract
Studies utilizing continuous flash suppression (CFS) provide valuable information regarding conscious and nonconscious perception. There are, however, crucial unanswered questions regarding the mechanisms of suppression and the level of visual processing in the absence of consciousness with CFS. Research suggests that the answers to these questions depend on the experimental configuration and how we assess consciousness in these studies. The aim of this review is to evaluate the impact of different experimental configurations and the assessment of consciousness on the results of the previous CFS studies. We review studies that evaluated the influence of different experimental configuration on the depth of suppression with CFS and discuss how different assessments of consciousness may impact the results of CFS studies. Finally, we review behavioral and brain recording studies of CFS. In conclusion, previous studies provide evidence for survival of low-level visual information and complete impairment of high-level visual information under the influence of CFS. That is, studies suggest that nonconscious perception of lower-level visual information happens with CFS, but there is no evidence for nonconscious high-level recognition with CFS.
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Color Can Shorten Breakthrough Times in Continuous Flash Suppression through Increased Salience and Task Relevance. Vision (Basel) 2021; 5:vision5010013. [PMID: 33809681 PMCID: PMC8006049 DOI: 10.3390/vision5010013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/09/2021] [Accepted: 03/11/2021] [Indexed: 11/16/2022] Open
Abstract
Color can enhance the perception of relevant stimuli by increasing their salience and guiding visual search towards stimuli that match a task-relevant color. Using Continuous Flash Suppression (CFS), the current study investigated whether color facilitates the discrimination of targets that are difficult to perceive due to interocular suppression. Gabor patterns of two or four cycles per degree (cpd) were shown as targets to the non-dominant eye of human participants. CFS masks were presented at a rate of 10 Hz to the dominant eye, and participants had the task to report the target’s orientation as soon as they could discriminate it. The 2-cpd targets were robustly suppressed and resulted in much longer response times compared to 4-cpd targets. Moreover, only for 2-cpd targets, two color-related effects were evident. First, in trials where targets and CFS masks had different colors, targets were reported faster than in trials where targets and CFS masks had the same color. Second, targets with a known color, either cyan or yellow, were reported earlier than targets whose color was randomly cyan or yellow. The results suggest that the targets’ entry to consciousness may have been speeded by color-mediated effects relating to increased (bottom-up) salience and (top-down) task relevance.
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Ananyev E, Yong Z, Hsieh PJ. Center-surround velocity-based segmentation: Speed, eccentricity, and timing of visual stimuli interact to determine interocular dominance. J Vis 2020; 19:3. [PMID: 31689716 DOI: 10.1167/19.13.3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We used a novel method to capture the spatial dominance pattern of competing motion fields at rivalry onset. When rivaling velocities were different, the participants reported center-surround segmentation: The slower stimuli often dominated in the center while faster motion persisted along the borders. The size of the central static/slow field scaled with the stimulus size. The central dominance was time-locked to the static stimulus onset but was disrupted if the dynamic stimulus was presented later. We then used the same stimuli as masks in an interocular suppression paradigm. The local suppression strengths were probed with targets at different eccentricities. Consistent with the center-surround segmentation, target speed and location interacted with mask velocities. Specifically, suppression power of the slower masks was nonhomogenous with eccentricity, providing a potential explanation for center-surround velocity-based segmentation. This interaction of speed, eccentricity, and timing has implications for motion processing and interocular suppression. The influence of different masks on which target features get suppressed predicts that some "unconscious effects" are not generalizable across masks and, thus, need to be replicated under various masking conditions.
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Affiliation(s)
- Egor Ananyev
- Nanyang Technological University, Department of Psychology, Singapore
| | - Zixin Yong
- Duke-NUS Medical School, Neuroscience and Behavioural Disorders Program, Singapore
| | - Po-Jang Hsieh
- National Taiwan University, Department of Psychology, Taipei, Taiwan
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7
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Individual variation in inter-ocular suppression and sensory eye dominance. Vision Res 2019; 163:33-41. [PMID: 31374237 DOI: 10.1016/j.visres.2019.07.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 07/10/2019] [Accepted: 07/22/2019] [Indexed: 11/20/2022]
Abstract
The competitive and inhibitory interactions between the two eyes' images are a pervasive aspect of binocular vision. Over the last decade, our understanding of the neural processes underpinning binocular rivalry (BR) and continuous flash suppression (CFS) has increased substantially, but we still have little understanding of the relationship between these two effects and their variation in the general population. Studies that pool data across individuals and eyes risk masking substantial variations in binocular vision that exist in the general population. To investigate this issue we compared the depth of inter-ocular suppression evoked by BR with that elicited by CFS, in a group (N = 25) of visually normal individuals. A noise pattern (either static for BR or dynamic for CFS) was presented to one eye and its suppressive influence on a probe grating presented simultaneously to the other eye was measured. We found substantial individual differences in the magnitude of suppression (a 10-fold variation in probe detection threshold) evoked by each task, but performance on BR was a significant predictor of performance on the CFS task. However many individuals showed marked asymmetries between the two eyes' ability to detect a suppressed target, that were not necessarily the same for the two tasks. There was a tendency for the magnitude of the asymmetry to increase as the refresh rate of the dynamic noise increased. The results suggest a common underlying mechanism is likely to be responsible, at least in part, for driving inter-ocular suppression under BR and CFS. The marked asymmetries in inter-ocular suppression at higher noise refresh rates, may be indicative of a difference in temporal processing between the eyes.
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Blake R, Goodman R, Tomarken A, Kim HW. Individual differences in continuous flash suppression: Potency and linkages to binocular rivalry dynamics. Vision Res 2019; 160:10-23. [PMID: 31002836 DOI: 10.1016/j.visres.2019.04.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 03/12/2019] [Accepted: 04/04/2019] [Indexed: 01/09/2023]
Abstract
Binocular rivalry (BR) and continuous flash suppression (CFS) are compelling psychophysical phenomena involving interocular suppression. Using an individual differences approach we assessed whether interocular suppression induced by CFS is predictable in potency from characteristics of BR that are plausibly governed by interocular inhibition. We found large individual differences in BR dynamics and, in addition, in the strength of CFS as gauged by the incidence and durations of breakthroughs in CFS during an extended viewing periods. CFS's potency waned with repeated trials, but stable individual differences persisted despite these mean shifts. We also discovered large individual differences in the strength of the post-CFS shift in BR dominance produced by interocular suppression. While CFS breakthroughs were significantly negatively correlated with shifts in BR dominance after CFS, there were no significant associations between individual differences in alternation rate during pre-CFS binocular rivalry and either breakthroughs during CFS or post-CFS dominance shifts. Bayesian hypothesis tests and highest posterior density intervals confirmed the weak association between these two forms of interocular suppression. Thus, our findings suggest that the substantial individual differences in BR dynamics and CFS effectiveness are modestly related but not entirely mediated by one common neural substrate.
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Affiliation(s)
- Randolph Blake
- Department of Psychology, Vanderbilt University, Nashville, TN 37212, USA; Vanderbilt Vision Research Center, Nashville, TN 37212, USA.
| | - Rachel Goodman
- Department of Psychology, Vanderbilt University, Nashville, TN 37212, USA
| | - Andrew Tomarken
- Department of Psychology, Vanderbilt University, Nashville, TN 37212, USA
| | - Hyun-Woong Kim
- Department of Psychology, Korea University, Seoul 02842, Republic of Korea
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Sensorimotor contingency modulates breakthrough of virtual 3D objects during a breaking continuous flash suppression paradigm. Cognition 2019; 187:95-107. [PMID: 30852262 DOI: 10.1016/j.cognition.2019.03.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 03/03/2019] [Accepted: 03/04/2019] [Indexed: 11/21/2022]
Abstract
To investigate how embodied sensorimotor interactions shape subjective visual experience, we developed a novel combination of Virtual Reality (VR) and Augmented Reality (AR) within an adapted breaking continuous flash suppression (bCFS) paradigm. In a first experiment, participants manipulated novel virtual 3D objects, viewed through a head-mounted display, using three interlocking cogs. This setup allowed us to manipulate the sensorimotor contingencies governing interactions with virtual objects, while characterising the effects on subjective visual experience by measuring breakthrough times from bCFS. We contrasted the effects of the congruency (veridical versus reversed sensorimotor coupling) and contingency (live versus replayed interactions) using a motion discrimination task. The results showed that the contingency but not congruency of sensorimotor coupling affected breakthrough times, with live interactions displaying faster breakthrough times. In a second experiment, we investigated how the contingency of sensorimotor interactions affected object category discrimination within a more naturalistic setting, using a motion tracker that allowed object interactions with increased degrees of freedom. We again found that breakthrough times were faster for live compared to replayed interactions (contingency effect). Together, these data demonstrate that bCFS breakthrough times for unfamiliar 3D virtual objects are modulated by the contingency of the dynamic causal coupling between actions and their visual consequences, in line with theories of perception that emphasise the influence of sensorimotor contingencies on visual experience. The combination of VR/AR and motion tracking technologies with bCFS provides a novel methodology extending the use of binocular suppression paradigms into more dynamic and realistic sensorimotor environments.
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Continuous flash suppression operates in local spatial zones: Effects of mask size and contrast. Vision Res 2018; 154:105-114. [PMID: 30481527 DOI: 10.1016/j.visres.2018.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 11/02/2018] [Accepted: 11/05/2018] [Indexed: 01/29/2023]
Abstract
Continuous flash suppression (CFS) is a technique in which presenting one eye with a dynamic Mondrian sequence prevents a low-contrast target in the other eye from being perceived for many seconds. Frequently used to study unconscious visual processing, CFS bears many similarities with binocular rivalry (BR), another popular dichoptic stimulation technique. It is therefore puzzling that the effect of mask size and contrast seem to differ between CFS and BR. To resolve this discrepancy, we conducted a systematic investigation on the effects of mask size and contrast in CFS. Also, building on findings from BR, we asked if the collinearity of the contours in the Mondrian masker play a role in CFS suppression. Our results showed a robust effect of mask contrast on suppression durations, and an effect of mask size that depended on collinearity. Specifically, higher mask contrasts produced longer suppression regardless of collinearity and mask size. Mask size, on the other hand, had little effect on suppression when collinearity was low and it weakened suppression when collinearity is high. These observations parallel prior findings in BR, further substantiating the close link between the two paradigms and demonstrating the usefulness of a shared explanatory framework describing both phenomena.
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Han S, Alais D. Battle of the Mondrians: Investigating the Role of Unpredictability in Continuous Flash Suppression. Iperception 2018; 9:2041669518792930. [PMID: 30151096 PMCID: PMC6108022 DOI: 10.1177/2041669518792930] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/11/2018] [Indexed: 11/24/2022] Open
Abstract
In continuous flash suppression (CFS), a dynamic sequence of Mondrian patterns presented to one eye suppresses a static target in the other eye for several seconds at a time. Its effectiveness has been linked to low-level properties such as spatial frequency and orientation, but the role of higher order influences remains unstudied. Here, using a tracking paradigm, we asked if the spatial and temporal predictability of the Mondrian sequence affects CFS dynamics. Predictable temporal sequences were regularly updated every 100 ms or modulated sinusoidally in pixel luminance at 2 Hz. Unpredictable temporal sequences were irregularly updated or had stochastic pixel luminance changes across time. To vary spatial predictability, sequences were either updated with different Mondrian patterns or had a fixed spatial pattern. We found a modest effect of spatial uncertainty when the target modulation was low (0.125 Hz) but not temporal uncertainty, which had no significant effects regardless of target modulation. Similar results were obtained when we pitted the standard Mondrian sequence against sequences with a fixed spatial pattern and temporally low-pass filtered sequences in a binocular rivalry paradigm. Thus, not only was the effect of information predictability was modest and spatial, but it was also dependent on the presence of higher temporal frequencies. Together, the results demonstrate the significance of low-level properties in affecting CFS dynamics and the possible involvement of pattern structure masking in CFS.
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Affiliation(s)
- Shui’Er Han
- School of Psychology, The University of Sydney, New South Wales, Australia
| | - David Alais
- School of Psychology, The University of Sydney, New South Wales, Australia
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12
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Ding Y, Naber M, Gayet S, Van der Stigchel S, Paffen CLE. Assessing the generalizability of eye dominance across binocular rivalry, onset rivalry, and continuous flash suppression. J Vis 2018; 18:6. [DOI: 10.1167/18.6.6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Yun Ding
- Department of Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, the Netherlands
| | - Marnix Naber
- Department of Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, the Netherlands
| | - Surya Gayet
- Donders Centre for Cognition, Donders Institute for Brain, Cognition & Behaviour, Radboud University, Nijmegen, the Netherlands
| | - Stefan Van der Stigchel
- Department of Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, the Netherlands
| | - Chris L. E. Paffen
- Department of Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, the Netherlands
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13
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Han S, Blake R, Alais D. Slow and steady, not fast and furious: Slow temporal modulation strengthens continuous flash suppression. Conscious Cogn 2018; 58:10-19. [PMID: 29309915 DOI: 10.1016/j.concog.2017.12.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 11/29/2017] [Accepted: 12/28/2017] [Indexed: 11/26/2022]
Abstract
Continuous flash suppression (CFS) involves the presentation of a rapidly changing Mondrian sequence to one eye and a static target in the other eye. Targets presented in this manner remain suppressed for several seconds at a time, and this has seen the prevalent use of CFS in studies of unconscious visual processes. However, the mechanisms behind CFS remain unclear, complicating its use and the comprehension of results obtained with the paradigm. For example, some studies report observations indicative of faster, visual masking processes whereas others suggest slower, rivalry processes. To reconcile this discrepancy, this study investigates the effect of temporal frequency content and Mondrian pattern structure on CFS suppression. Our results show predominant influences of spatial edges and low temporal-frequency content, which are similar to binocular rivalry, affording a parsimonious alternative in unifying the two paradigms.
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Affiliation(s)
- Shui'er Han
- School of Psychology, University of Sydney, NSW 2006, Australia.
| | - Randolph Blake
- Department of Brain and Cognitive Sciences, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-742, Republic of Korea; Department of Psychology, Vanderbilt University, Nashville, TN 37240, United States
| | - David Alais
- School of Psychology, University of Sydney, NSW 2006, Australia
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14
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Sun Y, Stein T, Liu W, Ding X, Nie QY. Biphasic attentional orienting triggered by invisible social signals. Cognition 2017; 168:129-139. [DOI: 10.1016/j.cognition.2017.06.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 06/18/2017] [Accepted: 06/19/2017] [Indexed: 11/30/2022]
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15
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Ananyev E, Penney TB, Hsieh PJB. Separate requirements for detection and perceptual stability of motion in interocular suppression. Sci Rep 2017; 7:7230. [PMID: 28775378 PMCID: PMC5543169 DOI: 10.1038/s41598-017-07805-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 06/29/2017] [Indexed: 11/09/2022] Open
Abstract
In interocular masking, a stimulus presented to one eye (the mask) is made stronger in order to suppress from awareness the target stimulus presented to the other eye. We investigated whether matching the features of the target and the mask would lead to more effective suppression (feature-selective suppression), or not (i.e., non-selective suppression). To control the temporal characteristics of the stimuli, we used a dynamic interocular mask to suppress a moving target, and found that neither matching speed nor pattern of motion led to more effective suppression. Instead, a faster target was detected faster, regardless of the mask type or speed, while a relatively slow (about 1°/s) mask was more perceptually stable (i.e., maintained suppression longer) in a non-selective fashion. While the requirement for target detectability, i.e., salience, is well characterized, relatively little attention is given to the factors that make a mask percept more perceptually stable. Based on these results, we argue that there are separate requirements for detection and perceptual stability.
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Affiliation(s)
- Egor Ananyev
- Department of Psychology, National University of Singapore, Singapore, Singapore.
| | - Trevor B Penney
- Department of Psychology, National University of Singapore, Singapore, Singapore.,LSI Programme in Neurobiology and Aging, National University of Singapore, Singapore, Singapore
| | - Po-Jang Brown Hsieh
- Neuroscience and Behavioral Disorders Program, Duke-NUS Medical School, Singapore, Singapore
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Moors P, Wagemans J, de-Wit L. Causal events enter awareness faster than non-causal events. PeerJ 2017; 5:e2932. [PMID: 28149698 PMCID: PMC5274517 DOI: 10.7717/peerj.2932] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Accepted: 12/21/2016] [Indexed: 11/20/2022] Open
Abstract
Philosophers have long argued that causality cannot be directly observed but requires a conscious inference (Hume, 1967). Albert Michotte however developed numerous visual phenomena in which people seemed to perceive causality akin to primary visual properties like colour or motion (Michotte, 1946). Michotte claimed that the perception of causality did not require a conscious, deliberate inference but, working over 70 years ago, he did not have access to the experimental methods to test this claim. Here we employ Continuous Flash Suppression (CFS)-an interocular suppression technique to render stimuli invisible (Tsuchiya & Koch, 2005)-to test whether causal events enter awareness faster than non-causal events. We presented observers with 'causal' and 'non-causal' events, and found consistent evidence that participants become aware of causal events more rapidly than non-causal events. Our results suggest that, whilst causality must be inferred from sensory evidence, this inference might be computed at low levels of perceptual processing, and does not depend on a deliberative conscious evaluation of the stimulus. This work therefore supports Michotte's contention that, like colour or motion, causality is an immediate property of our perception of the world.
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Affiliation(s)
- Pieter Moors
- Department of Brain and Cognition, Katholieke Universiteit Leuven , Leuven , Belgium
| | - Johan Wagemans
- Department of Brain and Cognition, Katholieke Universiteit Leuven , Leuven , Belgium
| | - Lee de-Wit
- Institute of Continuing Education, University of Cambridge, Cambridge, United Kingdom; Cognition and Language Sciences, University College London, University of London, London, United Kingdom
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No evidence for surface organization in Kanizsa configurations during continuous flash suppression. Atten Percept Psychophys 2016; 78:902-14. [PMID: 26704563 DOI: 10.3758/s13414-015-1043-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Does one need to be aware of a visual stimulus for it to be perceptually organized into a coherent whole? The answer to this question regarding the interplay between Gestalts and visual awareness remains unclear. Using interocular suppression as the paradigm for rendering stimuli invisible, conflicting evidence has been obtained as to whether the traditional Kanizsa surface is constructed during interocular suppression. While Sobel and Blake (2003) and Harris, Schwarzkopf, Song, Bahrami, and Rees (2011) failed to find evidence for this, Wang, Weng, and He (2012) showed that standard configurations of Kanizsa pacmen would break interocular suppression faster than their rotated counterparts. In the current study, we replicated the findings by Wang et al. (2012) but show that neither an account based on the construction of a surface nor one based on the long-range collinearities in the standard Kanizsa configuration stimulus could fully explain the difference in breakthrough times. We discuss these findings in the context of differences in the amplitudes of the Fourier orientation spectra for all stimulus types. Thus, we find no evidence that the integration of separate elements takes place during interocular suppression of Kanizsa stimuli, suggesting that this Gestalt involving figure-ground assignment is not constructed when rendered nonconscious using interocular suppression.
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18
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Han S, Lunghi C, Alais D. The temporal frequency tuning of continuous flash suppression reveals peak suppression at very low frequencies. Sci Rep 2016; 6:35723. [PMID: 27767078 PMCID: PMC5073327 DOI: 10.1038/srep35723] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 10/03/2016] [Indexed: 11/09/2022] Open
Abstract
Continuous flash suppression (CFS) is a psychophysical technique where a rapidly changing Mondrian pattern viewed by one eye suppresses the target in the other eye for several seconds. Despite the widespread use of CFS to study unconscious visual processes, the temporal tuning of CFS suppression is currently unknown. In the present study we used spatiotemporally filtered dynamic noise as masking stimuli to probe the temporal characteristics of CFS. Surprisingly, we find that suppression in CFS peaks very prominently at approximately 1 Hz, well below the rates typically used in CFS studies (10 Hz or more). As well as a strong bias to low temporal frequencies, CFS suppression is greater for high spatial frequencies and increases with increasing masker contrast, indicating involvement of parvocellular/ventral mechanisms in the suppression process. These results are reminiscent of binocular rivalry, and unifies two phenomenon previously thought to require different explanations.
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Affiliation(s)
- Shui'er Han
- School of Psychology, University of Sydney, NSW 2006, Australia
| | - Claudia Lunghi
- Department of Translational Research on New Technologies in Medicine and Surgery, Via Savi 10, 56100 Pisa, Italy.,Neuroscience Institute, National Research Council (CNR), Via Moruzzi 1, 56100, Pisa, Italy
| | - David Alais
- School of Psychology, University of Sydney, NSW 2006, Australia
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19
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Moors P, Wagemans J, de-Wit L. Faces in commonly experienced configurations enter awareness faster due to their curvature relative to fixation. PeerJ 2016; 4:e1565. [PMID: 26839746 PMCID: PMC4734451 DOI: 10.7717/peerj.1565] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 12/14/2015] [Indexed: 11/20/2022] Open
Abstract
The extent to which perceptually suppressed face stimuli are still processed has been extensively studied using the continuous flash suppression paradigm (CFS). Studies that rely on breaking CFS (b-CFS), in which the time it takes for an initially suppressed stimulus to become detectable is measured, have provided evidence for relatively complex processing of invisible face stimuli. In contrast, adaptation and neuroimaging studies have shown that perceptually suppressed faces are only processed for a limited set of features, such as its general shape. In this study, we asked whether perceptually suppressed face stimuli presented in their commonly experienced configuration would break suppression faster than when presented in an uncommonly experienced configuration. This study was motivated by a recent neuroimaging study showing that commonly experienced face configurations are more strongly represented in the fusiform face area. Our findings revealed that faces presented in commonly experienced configurations indeed broke suppression faster, yet this effect did not interact with face inversion suggesting that, in a b-CFS context, perceptually suppressed faces are potentially not processed by specialized (high-level) face processing mechanisms. Rather, our pattern of results is consistent with an interpretation based on the processing of more basic visual properties such as convexity.
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Affiliation(s)
- Pieter Moors
- Department of Brain & Cognition, Katholieke Universiteit Leuven , Leuven , Belgium
| | - Johan Wagemans
- Department of Brain & Cognition, Katholieke Universiteit Leuven , Leuven , Belgium
| | - Lee de-Wit
- Department of Brain & Cognition, Katholieke Universiteit Leuven , Leuven , Belgium
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Moors P, Stein T, Wagemans J, van Ee R. Serial correlations in Continuous Flash Suppression. Neurosci Conscious 2015; 2015:niv010. [PMID: 30619623 PMCID: PMC6307532 DOI: 10.1093/nc/niv010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Revised: 11/09/2015] [Accepted: 11/26/2015] [Indexed: 11/13/2022] Open
Abstract
Research on visual rivalry has demonstrated that consecutive dominance durations are serially dependent, implying that the underlying competition mechanism is not driven by some random process but includes a memory component. Here we asked whether serial dependence is also observed in continuous flash suppression (CFS). We addressed this question by analyzing a large dataset of time series of suppression durations obtained in a series of so-called “breaking CFS” experiments in which the duration of the period is measured until a suppressed target breaks through the CFS mask. Across experimental manipulations, stimuli, and observers, we found that (i) the distribution of breakthrough rates was fit less well by a gamma distribution than in conventional visual rivalry paradigms, (ii) the suppression duration on a previous trial influenced the suppression duration on a later trial up to as long as a lag of eight trials, and (iii) the mechanism underlying these serial correlations was predominantly monocular. We conclude that the underlying competition mechanism of CFS also includes a memory component that is primarily, but not necessarily exclusively, monocular in nature. We suggest that the temporal dependency structure of suppression durations in CFS is akin to those observed in binocular rivalry, which might imply that both phenomena tap into similar rather than distinct mechanisms.
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Affiliation(s)
- Pieter Moors
- Laboratory of Experimental Psychology, Department of Brain & Cognition, University of Leuven (KU Leuven), Belgium
| | - Timo Stein
- Center for Mind/Brain Sciences (CIMeC), University of Trento, Rovereto, Italy
| | - Johan Wagemans
- Laboratory of Experimental Psychology, Department of Brain & Cognition, University of Leuven (KU Leuven), Belgium
| | - Raymond van Ee
- Laboratory of Experimental Psychology, Department of Brain & Cognition, University of Leuven (KU Leuven), Belgium.,Donders Institute, Radboud University, Department of Biophysics, Nijmegen, The Netherlands.,Philips Research Laboratories, Department of Brain, Body & Behavior, Eindhoven, The Netherlands
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Moors P, Huygelier H, Wagemans J, de-Wit L, van Ee R. Suppressed visual looming stimuli are not integrated with auditory looming signals: Evidence from continuous flash suppression. Iperception 2015; 6:48-62. [PMID: 26034573 PMCID: PMC4441023 DOI: 10.1068/i0678] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Revised: 02/16/2015] [Indexed: 11/13/2022] Open
Abstract
Previous studies using binocular rivalry have shown that signals in a modality other than the visual can bias dominance durations depending on their congruency with the rivaling stimuli. More recently, studies using continuous flash suppression (CFS) have reported that multisensory integration influences how long visual stimuli remain suppressed. In this study, using CFS, we examined whether the contrast thresholds for detecting visual looming stimuli are influenced by a congruent auditory stimulus. In Experiment 1, we show that a looming visual stimulus can result in lower detection thresholds compared to a static concentric grating, but that auditory tone pips congruent with the looming stimulus did not lower suppression thresholds any further. In Experiments 2, 3, and 4, we again observed no advantage for congruent multisensory stimuli. These results add to our understanding of the conditions under which multisensory integration is possible, and suggest that certain forms of multisensory integration are not evident when the visual stimulus is suppressed from awareness using CFS.
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Affiliation(s)
- Pieter Moors
- Laboratory of Experimental Psychology, University of Leuven (KU Leuven), Leuven, Belgium; e-mail:
| | - Hanne Huygelier
- Laboratory of Experimental Psychology, University of Leuven (KU Leuven), Leuven, Belgium; e-mail:
| | - Johan Wagemans
- Laboratory of Experimental Psychology, University of Leuven (KU Leuven), Leuven, Belgium; e-mail:
| | - Lee de-Wit
- Laboratory of Experimental Psychology, University of Leuven (KU Leuven), Leuven, Belgium; e-mail:
| | - Raymond van Ee
- Laboratory of Experimental Psychology, University of Leuven (KU Leuven), Leuven, Belgium; Department of Biophysics, Donders Institute, Radboud University, Nijmegen, The Netherlands; Department of Brain, Body, & Behavior, Philips Research Laboratories, Eindhoven, The Netherlands; e-mail:
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Ludwig K, Hesselmann G. Weighing the evidence for a dorsal processing bias under continuous flash suppression. Conscious Cogn 2015; 35:251-9. [PMID: 25649867 DOI: 10.1016/j.concog.2014.12.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 12/11/2014] [Accepted: 12/16/2014] [Indexed: 10/24/2022]
Abstract
With the introduction of continuous flash suppression (CFS) as a method to render stimuli invisible and study unconscious visual processing, a novel hypothesis has gained popularity. It states that processes typically ascribed to the dorsal visual stream can escape CFS and remain functional, while ventral stream processes are suppressed when stimuli are invisible under CFS. This notion of a CFS-specific "dorsal processing bias" has been argued to be in line with core characteristics of the influential dual-stream hypothesis of visual processing which proposes a dissociation between dorsally mediated vision-for-action and ventrally mediated vision-for-perception. Here, we provide an overview of neuroimaging and behavioral studies that either examine this dorsal processing bias or base their conclusions on it. We show that both evidence for preserved ventral processing as well as lack of dorsal processing can be found in studies using CFS. To reconcile the diverging results, differences in the paradigms and their effects are worthy of future research. We conclude that given the current level of information a dorsal processing bias under CFS cannot be universally assumed.
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Affiliation(s)
- Karin Ludwig
- Visual Perception Laboratory, Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité - Universitätsmedizin, Berlin, Germany; Department of Psychology, Humboldt-Universität zu Berlin, Germany.
| | - Guido Hesselmann
- Visual Perception Laboratory, Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité - Universitätsmedizin, Berlin, Germany.
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