Multi-stable perception of structure-from-motion: differential priming selectivity distinguishes sensory memory and neural fatigue

Abstract

Ambiguous displays often lead to spontaneous alternations of mutually exclusive perceptions (multi-stable perception). Structure-from-motion (SFM) displays induce a vivid perception of a 3D volume rotating in depth, which reverses spontaneously from time to time. When an SFM display is interrupted briefly (~0.5 s), the current perception is destabilized by neural fatigue (adaptation). When the interruption is longer (>1 s), the current perception is stabilized by sensory memory (persistence). We have examined the neural representations that fatigue and that persist by characterizing their respective selectivities for 3D shape. We used a variety of SFM shapes, including rotationally symmetric and asymmetric shapes, as well as shapes defined by solid volume and by surface only. In a sensory memory condition, different stimuli were presented in random order (T_on=[1,2.5] s), separated by blank intervals (T_off= 1 s). In a neural fatigue condition, prime stimuli (stabilized by depth and size cues) were presented for T_prime=10 s, followed by blank intervals (T_off= 0.4 s) and randomly chosen probe stimuli (T_probe= 1 s). Contradicting earlier reports [Maier et al., 2002, Curr. Biol.], we find that sensory memory is shape-selective: 3D rotation is more stable when the same shape (rather than different shapes) are presented successively (ANOVA p<10[sup]-5[/sup]). Moreover, positive priming increases with shape similarity (r= 0.76, p<10[sup]-14[/sup]). In contrast, we find no shape-selectivity for neural fatigue: 3D rotation is destabilized comparably by same and different shapes (ANOVA p=0.7). Instead, some probes are more susceptible to aftereffects (from any prime) than others. We conclude that the visual representations of SFM that are subject to neural fatigue are not identical to the representations that maintain a sensory memory. This conflicts with the view that the same neural mechanisms mediate both positive and negative priming effects in multi-stable perception [Noest et al., 2007, J. Vis.].

Meeting abstract presented at VSS 2013