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Eveline Mu, Laila Hugrass, David P Crewther; Red background facilitates low spatial frequency fearful face processing in groups with high autistic tendency. Journal of Vision 2019;19(10):24d. doi: https://doi.org/10.1167/19.10.24d.
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© ARVO (1962-2015); The Authors (2016-present)
Wiesel and Hubel (1966) showed that diffuse red light suppresses firing rates of Type IV magnocellular (MC) cells, prompting human behavioural studies to use spatial frequency filtering and red backgrounds to intuit MC contributions to face processing, reporting a reduction in MC efficiency with red backgrounds. However, no human electrophysiological study, to date, has investigated whether red backgrounds influence the rapid effects of fearful expressions on visual evoked potentials (VEPs). Here we measured performance accuracy and early event-related potentials (P100 and N170) in response to low- and high-spatial frequency fearful and neutral faces, which were presented on red and green backgrounds of the same luminance. Examining the effects of red surrounds on Type IV MC cells may also provide insight into the commonly reported MC abnormality in groups with higher autistic traits. Thus, responses were compared for groups of neurotypical adults with low (n=21, AQ mean = 8.6±2.7) and high (n=22, AQ mean = 29±7.4) scores on the Autistic Spectrum Quotient (AQ). Unexpectedly (Awasthi et al., 2016), there were no substantial effects of background colour on emotion identification accuracy for either AQ group (p=0.35). This finding may be explained by the long presentation duration (500ms) allowing for conscious percept and MC recovery. Our VEP data showed that fearful expressions produced greater P100 amplitude when presented on a green background (p=0.04), but not when presented on a red background (p=0.70). Interestingly, however, red surrounds increased the P100 amplitude for low spatial frequency fearful stimuli for the high AQ group (p=0.04). Our findings suggest that suppressing the Type IV MC cells facilitates rapid VEP responses to fearful emotion for groups with MC abnormalities such as high AQ, yet it has the opposite effort for those with low AQ.
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