Unconscious postdictive properties of perception as demonstrated in apparent motion. An EGG study

Abstract

This research was focused on postdictive properties of apparent motion — an illusion of movement resulting from successive presentation of two dots. Obviously, the mechanisms of integration of two dots' representations can take place only after the second dot is presented. There are two alternatives of what exactly happens. Firstly, a person becomes aware of the frst dot, then the second dot, and then reconstructs his or her memories of what he or she just saw. Secondly, the person becomes aware of the frst dot, and unconscious integration occurs before he/she becomes aware of the second dot, so that the person becomes aware of the sum “sense of motion + second dot”. Our research revealed evidence in favor of the latter— unconscious integration. During the experiment, participants observed stimuli corresponding to different levels of illusory strength or lack of illusion. Signifcant differences in amplitudes of ERP components P100 and N200 can be related to qualitative differences in awareness of the second dot, depending on the strength of illusion. This means that these differences are determined by unconscious integration that happened prior to awareness. Signifcant differences of alpha-band power up to 300 ms after the second dot's onset demonstrate that unconscious integration can be performed at the expense of suppression of the alpha-band. Thus, the contents of perception which a person apprehends can be described as unconscious ntegration of stimuli, captured in a small time interval prior to the moment of awareness. Going forward, we can seek to determine more precisely the characteristics of tendencies revealed in the present study.