Limitations
Although a strength of the study is the large sample, we relied on an
online format. This left uncontrolled a host of viewing parameters
(e.g., image resolution, lighting, person-to-screen distances, screen
dimensions) we would prefer to control. These sources of noise are
likely equivalent across participants, and we see significant effects.
The added noise may weaken effects compared to in person testing. This
is worth revisiting with in person testing going forward. Online data
collection prevented us from linking visual illusion findings in SSD
with neural mechanisms (e.g., Thakkar et al., 2019). The number of
illusions seen in the PGT has been associated with cortical
hyperexcitability in visual cortex (Braithwaite et al., 2015;
Fong et al., 2020), though we did not measure this in the current study,
and cannot confirm this in our samples. It is possible that
cortical hyperexcitability/hyporeactivity fluctuates across the cortex.To capture the underlying mechanism accounting for the relationship
between high schizotypy and illusory percepts we are now collecting
neural responses during task performance. The absence of neural measures
leaves open an alternative hypothesis that there is a signal detection
difference that shifts response criterion in those with higher
schizotypy scores. In other words, those with high schizotypy might bemore inclined to report that an illusion was perceived than those
with lower scores (Sahakyan & Kwapil, 2019), and thus we could be
capturing a response bias rather than a difference in perceptual
experiences.