Observers can reliably identify illusory flashes in the illusory flash paradigm

Abstract

In the illusory flash paradigm, a single flash may be experienced as two flashes when accompanied by two beeps or taps, and two flashes may be experienced as a single flash when accompanied by one beep or tap. The classic paradigm restricts responses to '1' and '2' (2-AFC), ignoring possible qualitative differences between real and illusory flashes and implicitly assuming that illusory flashes are indistinguishable from real flashes. We added a third response category 'different from that of either 1 or 2 flashes' (3-AFC). Eight naïve and 6 experienced observers responded to 160 real and 160 illusory flash trials. Experienced observers were exposed to 1,200 trials before the experiment but without receiving feedback on their performance. The third response category was used for only 4 % of the real flash trials and for 44 % of the illusory flash trials. Experienced observers did so more often (78 %) than naïve observers (18 %). This shows that observers can reliably identify illusory flashes and indicates that mere exposure to illusory flash trials (without feedback) is enough to detect and classify potential qualitative differences between real and illusory flashes.

Individual Differences in Alpha Frequency Drive Crossmodal Illusory Perception

“…Accordingly, acceleration of response times to the illusion is akin to that induced by physical flashes [ 12 ]. The illusory visual percept is mediated by early crossmodal interactions in low-level visual cortices [ 13 ], and its occurrence is predicted by alpha band occipital oscillatory amplitude [ 14, 15 ] enhanced coherence between auditory and visual areas [ 16 ] and is undistinguishable from real flashes in naive participants [ 17 ]. Moreover, proneness to this illusion has been linked to local gray matter volume in early visual cortices [ 18 ].…”

Effects of Aging in Multisensory Integration: A Systematic Review

“…However, an object integrated by more than one sensory system captures one’s attention more efficiently and proves that bottom-up integration can “drive” attention (Talsma, 2015). Additionally, the integration of stimuli depends on its relevance, for instance, a task-irrelevant sound associated with an attended visual stimuli will be more likely to be integrated compared to a task-irrelevant sound associated with an unattended visual stimulus (Guerreiro et al, 2010; van Erp et al, 2013; Talsma, 2015). Similar effects are found for visual and tactile stimuli (Philippi et al, 2008; Werkhoven et al, 2009; van Erp et al, 2014).…”

Visual sensitivity is a stronger determinant of illusory processes than auditory cue parameters in the sound-induced flash illusion

“…The mechanisms underlying illusory flash percepts remain uncertain; while the illusory flash has been shown to have a measurable contrast (McCormick & Mamassian, 2008), experienced subjects are able to determine differences between real and illusory flashes when given a third (''not one, not two'') response option (van Erp, Philippi, & Werkhoven, 2013). Neural imaging experiments demonstrate that illusory flashes are accompanied by activity in visual cortex, but that this activity differs from that elicited by real flashes (Mishra, Martinez, & Hillyard, 2008;Mishra, Martinez, Sejnowski, & Hillyard, 2007;Shams, Iwaki, Chawla, & Bhattacharya, 2005;Shams, Kamitani, Thompson, & Shimojo, 2001).…”