Early visual structures, like the primary visual cortex (V1), have an active role during size perception. We examined interocular transfer in a priming task both within and outside of awareness using continuous flash suppression (CFS). Specifically, stimulus sequences in which a prime and target that were either size-congruent or size-incongruent could be presented in succession to the same eye (monocular condition) or separately to each eye (dichoptic condition). This design enables one to infer the relative contributions of early and later visual structures, as monocular channels remain segregated in early visual areas (like V1 and earlier), but begin to coalesce in the cortex (V1 and beyond). Thus, equivalent reaction times across same and different eye presentations (i.e., interocular transfer) would highlight the importance of later visual areas. Thirty-five participants (Mage = 25.2 years) completed the experiment. Participants categorised a target stimulus as either small or
large. Trials varied prime visibility (CFS vs. visible), prime and target congruency (congruent vs. incongruent size), and eye presentation (monocular vs. dichoptic). A three-way ANOVA revealed a Congruency × Visibility interaction, F(1, 34) = 6.08, p = .02, ?2 p = .15, which was driven by priming effects in the visible (p < .05, d = .25, BF10 = 18.45) but not CFS (p = .99, d = .03, BF10 = 0.23) conditions. There was also an Eye × Visibility interaction, F(1, 34) = 17.10, p < .01, ?2 p = .34, which was driven by a monocular advantage under CFS (p < .01, d = .36, BF10 = 91.25), whereas monocular and dichoptic presentations were equivalent during the visible condition (p = .97, d = .03, BF10 = .21). Taken together, priming effects in the visible but not CFS conditions suggest that awareness is an enabling factor for size perception to occur. Further, we can infer that this is likely mediated by later visual structures, as there was complete interocular transfer of the size information.
|Peel, H. J., Sherman, J. A., Sperandio, I., Laycock, R., & Chouinard, P. A. (November 2018) The mechanisms of size perception inferred by continuous flash suppression and interocular transfer. Abstract Book of the 8th Annual Meeting of the Australasian Cognitive Neuroscience Society (p. 75). The University Melbourne, VIC, Australia.|