Perceptual overloading reveals illusory contour perception without awareness of the inducers

Abstract

Unconscious perception is frequently examined by restricting visual input (e.g., using short stimulus durations followed by masking) to prevent that information from entering visual awareness. Failures to demonstrate perception without awareness may thus be a consequence of this restricted input rather than of limitations in unconscious perception. Here, we demonstrate a novel method that circumvents these significant drawbacks inherent in other methods. Using this new perceptual overloading technique (POT), in which stimuli are repeatedly presented in alternation with a stream of variable masks, we demonstrate illusory contour perception and modal completion even when subjects are completely unaware of the inducing elements. In addition to demonstrating a powerful new method to study consciousness by effectively gating robust visual input from visual awareness, we show that more complex contextual effects, previously considered to be a privilege only of conscious vision, can occur without awareness.

Working Memory and Consciousness: The Current State of Play

“…But one well-known pitfall for studies that involve the technique of visual masking is that it typically involves brief presentation times and masks that inevitably degrade the stimuli, thereby reducing their signal strength. Consequently, some theorists have speculated that the fact that we have not decisively experimentally demonstrated many higher cognitive functions occurring unconsciously may be an artifact of our current methods for masking stimuli (e.g., Lau, 2009 ; Persuh et al, 2016 ). Thus, were a legitimate study of unconscious VWM involving masking to be devised, the failure of participants to successfully perform the memory task might be explained not by the fact that the unconsciously information cannot be encoded in VWM, but by the fact that unconscious perception, as it is currently studied, is typically weak.…”

“…In a standard masked-priming experiment, for example, stimuli are presented briefly and masked so that they are rendered invisible; yet such stimuli are nonetheless thought to be perceived unconsciously because they prime or affect downstream behavioral responses (Kouider and Dehaene, 2007 ). In some experimental paradigms, stimuli are masked and presented for longer durations (Tsuchiya and Koch, 2005 ; Persuh et al, 2016 ). Some type of memory store is implicated in such studies, as behavioral responses are performed in the absence of the perceived objects.…”

Weak experiences sufficient for creating illusory figures that influence perception of actual lines

“…perception of the amount of visual energy), cannot induce the illusion–only perception of the full stimulus can. The conclusion of the experiment depends on two assumptions: 1) That the Kanizsa illusion does not have an effect on behaviour when perceived unconsciously (for a short review, generally supporting this assumption, see [29]). And 2) that the illusion is only perceived when all inducers are perceived.…”

“…In one paper a special kind of mask was applied alternating the stimulus with a randomly generated mask of inducer shapes with a total display time of 960 ms. In this setup, participants could distinguish an illusory diamond from an illusory square better than chance, while not being significantly better than chance to report properties of the inducers [29]. In the other paper, the performance of distinguishing the orientation of an actual low contrast triangle and a Kanizsa triangle was compared [30].…”

A Brief Argument For Consciousness Without Access

“…For instance, the use of masking might degrade the quality of non‐conscious representations, in such a way that poor performance in Soto et al . 's () paradigm could be an artefact of experimental methods (Persuh et al ., ). However, this does not offer a positive argument for why unconscious processing might be sufficient for task completion, and so as Block (, p. 575) points out, it is ‘a mistake to suppose that unconscious images are somehow the default view’.…”