Visual imagery vividness correlates with afterimage brightness and sharpness

Sharif Kronemer
Micah Holness
Tyler Morgan
Joshua Teves
Javier Gonzalez-Castillo
Daniel Handwerker
Peter Bandettini

Afterimages are illusory, conscious visual perseverations commonly induced by preceding light stimulation. A retinal centric view on the physiological source of afterimages is dominant. In addition, post-retinal mechanisms have been considered in the formation and modulation of afterimage perception, including cortical processes. A cortical role in afterimage perception posits possible shared neural mechanisms between afterimages and other conscious perceptions that emerge completely from central neural sources (e.g., imagery, hallucination, and dreams). To examine this hypothesis, we tested a perceptual link between afterimages and visual imagery. Framing the current experiment, we review more than a century of literature that evidences post-retinal processes in afterimage perception. Subsequently, we present an innovative afterimage perception reporting paradigm, validated on image stimuli, that allowed participants to indicate the perceived sharpness, contrast, and duration of their afterimages. From these perceptual reports, we discovered a novel category of evidence for cortical mechanisms in afterimage perception: the vividness of visual imagery positively correlates with afterimage brightness and sharpness. This result motivates future investigations on the neural mechanisms of afterimage perception and encourages implementing afterimages as a model perception to interrogate other kinds of conscious experience with known cortical origin.

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