VEP Responses to Op-Art Stimuli

Abstract

Several types of striped patterns have been reported to cause adverse sensations described as visual discomfort. Previous research using op-art-based stimuli has demonstrated that spurious eye movement signals can cause the experience of illusory motion, or shimmering effects, which might be perceived as uncomfortable. Whilst the shimmering effects are one cause of discomfort, another possible contributor to discomfort is excessive neural responses: As striped patterns do not have the statistical redundancy typical of natural images, they are perhaps unable to be encoded efficiently. If this is the case, then this should be seen in the amplitude of the EEG response. This study found that stimuli that were judged to be most comfortable were also those with the lowest EEG amplitude. This provides some support for the idea that excessive neural responses might also contribute to discomfort judgements in normal populations, in stimuli controlled for perceived contrast.

A neural correlate of visual discomfort from flicker

“…While several studies have examined the effect of stimulus variation upon visual cortex neural response or upon reports of visual discomfort, only a few studies have combined these measurements. O'Hare and colleagues (2015) reported a positive correlation between the visual discomfort evoked by static “Op art” images and VEP response across a range of spatial frequencies. Haigh et al (2013 , 2019 ) demonstrated that parametric variation in the color separation of isoluminant gratings was related to greater reported discomfort, greater visual cortex hemodynamic responses (as measured by near-infrared spectroscopy), and greater cortical response as measured by VEP.…”

Steady‐state VEP responses to uncomfortable stimuli

“…On average, there was a statistically significant effect of spatial frequency (λ) on discomfort judgements, with thinner stripes being judged more comfortable. This is similar to the findings of previous investigations (O'Hare et al ., ). The peak SSVEP response from the O1 channel was greater for the midrange spatial frequencies compared to the high and low spatial frequencies.…”

“…Stimuli consisted of nine riloid patterns, the same as used in O'Hare et al . (). These are based on the work of Zanker et al .…”

“…Elegant work has matched the SSVEP response period to the ERP latency in the case of faces (Rossion & Jacques, ). Previous work has shown P100 is important component in the context of visual discomfort (O'Hare et al ., ). The reciprocal of P100 is 10 Hz, therefore 10 Hz stimulation is one candidate frequency for investigation in this study.…”

“…There is evidence that discomfort from gratings is related to the haemodynamic brain response, for both black and white (Coutts et al ., ) and chromatic gratings (Haigh et al ., , ). There is also some evidence for increased visual evoked potentials on viewing black‐and‐white riloid stimuli: stimuli that were most comfortable were also those with a lower event‐related potential (ERP) response amplitude, specifically the P100 response (O'Hare et al ., ). However, the P100 response did not entirely follow the clear tuning for discomfort.…”