Abstract
Continuous flash suppression (CFS) is a psychophysical technique where a rapidly flickering 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 unknown yet is thought to require high temporal frequencies. We used spatiotemporal filtering of dynamic noise patterns to produce narrow-band masking stimuli which were used to probe the temporal, spatial and orientation characteristics of CFS. Surprisingly, CFS suppression with narrowband stimuli peaks very prominently at approximately 1 Hz, well below the rates typically used in CFS studies (10 Hz or more). As these studies generally use a flickering Mondrian pattern – a broad-band stimulus – our finding shows it is the low-frequency component of the Mondrian that is responsible for most of the suppression. As well as being strongly low-temporal-frequency biased, CFS suppression is greater for high spatial frequencies and for increasing masker contrast. Selectivity for low temporal and high spatial frequencies, and a rising monotonic contrast function, suggest parvocellular/ventral mechanisms underlie CFS suppression. These results are similar to findings in binocular rivalry, and thus unify two phenomenon previously thought to require different explanations. While high temporal frequency maskers can induce CFS suppression, it is much weaker – whether measured in target suppression duration or target contrast threshold elevation. Using orientation filtering, we found another difference between low- and high-temporal frequency CFS suppression: at low frequencies, CFS suppression is strongly orientation tuned while at high frequencies orientation selectivity is much weaker.
Meeting abstract presented at VSS 2017