title: Time for Awareness: The Influence of Temporal Properties of the Mask on Continuous Flash Suppression Effectiveness.
abstract: Visual processing is not instantaneous, but instead our conscious perception depends on the integration of sensory input over time. In the case of Continuous Flash Suppression (CFS), masks are flashed to one eye, suppressing awareness of stimuli presented to the other eye. One potential explanation of CFS is that it depends, at least in part, on the flashing mask continually interrupting visual processing before the stimulus reaches awareness. We investigated the temporal features of masks in two ways. First, we measured the suppression effectiveness of a wide range of masking frequencies (0-32Hz), using both complex (faces/houses) and simple (closed/open geometric shapes) stimuli. Second, we varied whether the different frequencies were interleaved within blocks or separated in homogenous blocks, in order to see if suppression was stronger or weaker when the frequency remained constant across trials. We found that break-through contrast differed dramatically between masking frequencies, with mask effectiveness following a skewed-normal curve peaking around 6Hz and little or no masking for low and high temporal frequencies. Peak frequency was similar for trial-randomized and block randomized conditions. In terms of type of stimulus, we found no significant difference in peak frequency between the stimulus groups (complex/simple, face/house, closed/open). These findings suggest that temporal factors play a critical role in perceptual awareness, perhaps due to interactions between mask frequency and the time frame of visual processing.
authors.affiliation: School of Information Science, Yunnan University, Kunming, China.|Center for Mind/Brain Sciences (CIMeC), University of Trento, Rovereto, Italy.|Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.
authors.forename: Weina
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Center for Mind/Brain Sciences (CIMeC), University of Trento, Rovereto, Italy.
authors.forename: Jan
authors.initials: J
authors.lastname: Drewes
authors.affiliation: Center for Mind/Brain Sciences (CIMeC), University of Trento, Rovereto, Italy.
authors.forename: David
authors.initials: D
authors.lastname: Melcher
mesh_terms: D000328:Adult; D001364:Awareness / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D010470:Perceptual Masking / Q000502:physiology*; D010775:Photic Stimulation; D013997:Time Factors; D013998:Time Perception / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult