Feature-based interaction between masks and target in continuous flash suppression

Abstract

Continuous flash suppression (CFS) has become one of the most popular tools in the study of visual processing in the absence of conscious awareness. Studies use different kinds of masks, like colorful Mondrians or random noise. Even though the use of CFS is widespread, little is known about some of the underlying neuronal mechanisms, such as the interactions between masks and stimuli. We designed a b-CFS experiment with feature-reduced targets and masks in order to investigate possible effects of feature-similarity or -orthogonality between masks and targets. Masks were pink noise patterns filtered with an orientation band pass to generate a strong directionality. Target stimuli were Gabors varying systematically in their orientational alignment with the masks. We found that stimuli whose orientational alignment was more similar to that of the masks are suppressed significantly longer. This feature-similarity (here: orientation) based enhancement of suppression duration can be overcome by feature orthogonality in another feature dimension (here: color). We conclude that mask–target interactions exist in continuous flash suppression, and the human visual system can use orthogonality within a feature dimension or across feature dimensions to facilitate the breaking of the CFS.

Band-limited interactions between mask and target in continuous flash suppression

“…Only few studies directly investigated mask design with respect to the target stimuli (Drewes et al, 2023;Han et al, 2021). Recently, we provided evidence for the existence of strong interactions between the masks and the stimuli in CFS (Drewes et al, 2023). Together with others (Han et al, 2021;Moors et al, 2017), this shows that the suppression achieved in CFS is not global or general, but largely speci c and feature dependent.…”

“…Previous research has already indicated that spatial frequency is also an important factor in CFS (Drewes et al, 2018;Yang & Blake, 2012), although not immediately in the context of mask/stimulus interactions. A stimulus with spatial orientation cannot exist without a spatial frequency; to avoid possible effects of the interaction between spatial frequencies, in our previous study (Drewes et al, 2023) target stimuli with a single spatial frequency were paired with masks that covered a very wide range of spatial frequencies -based on pink noise, with 1/f frequency slope, as suggested in (Drewes et al, 2020). While we will assume that general mask/stimulus interactions in CFS truly exist, the question arises if the orientation-dependent interaction between masks and targets would persists across spatial frequency bands, or if this interaction requires comparable spatial frequency content between masks and targets.…”

“…While it has been shown that the properties of the masks in uence suppression effectiveness in multiple ways (Drewes et al, 2018(Drewes et al, , 2020Han et al, 2016Han et al, , 2019, in many cases, the masks used in the relevant studies were treated as independent of the targets, or at least were not designed with speci c targets in mind (Drewes et al, 2023;Pournaghdali & Schwartz, 2020). Only few studies directly investigated mask design with respect to the target stimuli (Drewes et al, 2023;Han et al, 2021). Recently, we provided evidence for the existence of strong interactions between the masks and the stimuli in CFS (Drewes et al, 2023).…”

“…This question has important implications on the interpretation of any differences in break-through time between target categories obtained in CFS paradigms, as differences in break-through time are frequently considered to re ect differences in unaware processing of visual stimuli (Stein et al, 2011;Yang et al, 2014), yet may be confounded with differences in the effectiveness of the masking (Drewes et al, 2023).…”

A new ‘CFS tracking’ paradigm reveals uniform suppression depth regardless of target complexity or salience

“…Many substantive questions remain. For example, the depth of interocular suppression is reported to partially depend on spatial feature similarity between the competing images (Alais & Melcher, 2007;Drewes et al, 2023) and their temporal frequency . These factors could be parametrically varied to examine specifically whether they modulate bCFS thresholds alone, or whether they also cause a change in suppression depth by asymmetrically affecting reCFS thresholds.…”