Pupil Constriction in the Glare Illusion Modulates the Steady-State Visual Evoked Potentials

Effect of glare illusion‐induced perceptual brightness on temporal perception

“…In fact, the pupil area at the PLR peak induced by the glare stimuli was only approximately 34% in comparison with the halo stimuli, despite the physical equiluminance. Recently, Suzuki and colleagues reported that the amplitude of steady‐state visual evoked potentials (SSVEPs), electroencephalography (EEG) signals representing feature‐selective attention positively correlated with visual stimulus clarity, and surprisingly decreased in association with the glare illusion compared to control stimuli (Y. Suzuki et al., 2019 ). Furthermore, the study described the probable mechanism of this inhibited SSVEP as a causal relationship of glare illusion‐induced pupil constriction in the primary stages of visual processing and the decrease of light entering the pupil.…”

“…Considering coding efficiency model into account, a study by Murray et al found that illusionary stimuli to be perceived as larger evoked greater cortical activity in V1 (Murray et al., 2006 ); this may explain the results by Ono and Kawahara that found that the same physical magnitude can extend subjective duration by illusionary larger objects (Ono & Kawahara, 2007 ), which also supports the supposition that subjective magnitude itself is sufficient to induce temporal illusions and explain the context‐dependency of non‐temporal effects on temporal perception. However, although Ono and Kawahara consider that temporal perception is also influenced by later processing related to visual illusions, considering bidirectional interactions in visual processing (Lollo et al., 2000 ), and the neural activity alteration resulting from pupillary constriction (Bombeke et al., 2016 ; Suzuki et al., 2019 ), the perceptual stage involved in temporal illusions is still speculative.…”

“…Additionally, pupil diameter is known to reflect not just the physical luminance of the environment but various physiological internal states as well as the subjective brightness derived from the stimuli (Binda et al., 2013 ; Laeng et al., 2012 ; Mathot, 2018 ; Naber & Nakayama, 2013 ). Accordingly, several studies have reported pupil diameter to also reflect the perceptual brightness conveyed by the glare illusion, despite the physical luminance being identical to the control stimuli (Laeng & Endestad, 2012 ; Laeng et al., 2018 ; Suzuki et al., 2019 ; Zavagno et al., 2017 ).…”

Glossiness perception and its pupillary response

“…Similar to arousal activities leading to pupil dilation, recent studies have revealed that cognitive factors constrict the pupil. For example, illusory brightness caused by the self-luminosity of the glare illusion causes pupil constriction as a cognitive factor (Kinzuka et al, 2021; Suzuki, Minami, & Nakauchi, 2019; Suzuki, Minami, Laeng, et al, 2019). These studies allowed us to hypothesize that changes in pupil responses are induced by glossiness perception.…”

“…Specifically, specular highlight components structured by brighter regions in an image would constrict the pupil diameters. We expected that this characteristic phenomenon would occur due to one of the cognitive factors wherein we perceive an object to be glossy because the pupil diameter responds to both subjective and perceptual brightness (Laeng et al, 2018; Laeng & Endestad, 2012; Suzuki, Minami, & Nakauchi, 2019; Suzuki, Minami, Laeng, et al, 2019; Zavagno et al, 2017). If we can understand how the pupil reacts to glossy objects, the outcomes can be used to develop a new tool to estimate perceived glossiness or visual material perception without any explicit behavioral responses from human observers.…”