Long-lasting visual integration of form, motion, and color as revealed by visual masking

Abstract

When two similar visual stimuli are presented in rapid succession at the same location, they fuse. For example, a red and a green disk are perceived as one single yellow disk. Likewise, verniers with opposite offset directions are perceived as one vernier with an almost aligned vernier offset. In fusion, observers have no conscious access to the individual stimuli. Using transcranial magnetic stimulation (TMS), it has been shown that feature fusion for verniers can be modulated for about 400 ms in that either the first or the second vernier dominates the percept, depending on TMS onset. Here, we use light masks to modulate feature fusion for verniers, motion, and color. Our results are similar to the TMS experiment and show that individual visual features are stored for a substantial amount of time before they are integrated.

What Happens in a Moment

“…Scharnowski et al ( 2009 ) and Pilz et al ( 2013 ) have found that stimuli perceived as fused in time (i.e., co-temporal) may in fact be initially processed as temporally segregated. In these studies, the authors used stimuli presented in sequence over short time intervals that lead to a temporally fused percept.…”

“…In these studies, the authors used stimuli presented in sequence over short time intervals that lead to a temporally fused percept. They applied either TMS (Scharnowski et al, 2009 ) or masking (Pilz et al, 2013 ) at different delays to disturb information processing, and examined which of the two successive stimuli dominated the perception. This procedure allowed them to establish that the processing of the two successive stimuli can be disturbed distinctly and in turn.…”

“…The implicit ability to discriminate stimuli in time may play a special role in the processing of visual information, by providing the means to follow stimuli over time at an implicit level and with a high temporal accuracy. The possibility that stimuli are processed successively at an unconscious level is suggested by the studies of Scharnowski et al ( 2009 ) and Pilz et al ( 2013 ). Elliott et al ( 2007 ) also suggested that the processing of short asynchronies can be modulated by prior temporal information, i.e., pairs of events whose simultaneity or asynchrony was made non-detectable by the presence of distracters.…”

Invisibility and interpretation

“…We like to add that vernier fusion, as well as color and motion fusion, can be manipulated also by light masks, instead of TMS (Pilz et al, 2013). …”

Using the Simon Effect in Simultaneity/Asynchrony Discrimination Tasks: Interest, Methods, and Limits

“…In the primary visual cortex, specialized pathways are used to process contour and surface information: neurons will respond selectively to orientation, code line-ends, and edges, or they will be activated by information related to color or texture. Whichever model is used to understand how information is bound together to identify forms and objects, time is required, because ambiguities regarding which information belongs to which object is often ambiguous (Grossberg & Pilly, 2008;Pugeault, Wörgötter, & Krüger, 2010) and because it is also possible to mentally group or re-group objects (Pilz et al, 2013;Van Assche, Gos, & Giersch, 2008). A series of mechanisms are, thus, required to identify an object.…”