Contextual influence on the tilt after-effect in foveal and para-foveal vision

Abstract

A sensory stimulus can only be properly interpreted in light of the stimuli that surround it in space and time. The tilt illusion (TI) and tilt after-effect (TAE) provide good evidence that the perception of a target depends strongly on both its spatial and temporal context. In previous studies, the TI and TAE have typically been investigated separately, so little is known about their co-effects on visual perception and information processing mechanisms. Here, we considered the influence of the spatial context and the temporal effect together and asked how centersurround context affects the TAE in foveal and parafoveal vision. Our results showed that different center-surround spatial patterns signifi cantly affected the TAE for both foveal and para-foveal vision. In the fovea, the TAE was mainly produced by central adaptive gratings. Cross-oriented surroundings significantly inhibited the TAE, and iso-oriented surroundings slightly facilitated it; surround inhibition was much stronger than surround facilitation. In the para-fovea, the TAE was mainly decided by the surrounding patches. Likewise, a cross-oriented central patch inhibited the TAE, and an iso-oriented one facilitated it, but there was no significant difference between inhibition and facilitation. Our findings demonstrated, at the perceptual level, that our visual system adopts different mechanisms to process consistent or inconsistent central-surround orientation information and that the unequal magnitude of surround inhibition and facilitation is vitally important for the visual system to improve the detectability or discriminability of novel or incongruent stimuli.

Adaptation reveals that facial expression averaging occurs during rapid serial presentation

“…During adaptation, subjects were simply asked to concentrate on the central fixation cross, but not the RSVP face stream in the peripheral region. It has been shown that presenting stimuli in the visual periphery generates larger adaptation aftereffects than when presented at the fovea (on tilt aftereffect, see Chen, Chen, Gao, Yang, & Yan, 2015; on color adaptation, see Bachy & Zaidi, 2014). Therefore, subjects may involuntarily or unconsciously group all of the faces together into an ensemble representation.…”

The Illusion of Uniformity Does Not Depend on the Primary Visual Cortex: Evidence From Sensory Adaptation

“…Note, however, that the size of each grid cell (3 dva) is larger than the diameter of most receptive fields at V1 (around 1 dva; Bentley & Salinas, 2009 ), and the relationship between stimulus size and TAE strength is not always intuitive ( Harris & Calvert, 1985 ; Parker, 1972 ). Another possibility involves extraclassical receptive field effects exerted by the global surround on the adapting Gabor when the latter takes the global orientation (iso-orientation surround suppression; Chen, Chen, Gao, Yang, & Yan, 2015 ). Whatever the contribution of these effects, they act differently on physical compared with illusory iso-orientation, in the manner expected for low-level processing of the former, but not the latter.…”

Temporal and spatial ensemble statistics are formed by distinct mechanisms

“…The adapting stimuli and the test stimuli were always presented at the same side of the central fixation cross within one trial, and their centers were roughly 3.8° away from the central fixation cross (159 pixels). Our reason for presenting the faces in the periphery was because adaptation aftereffects have been found to be greater in the visual periphery compared to the fovea (Bachy & Zaidi, 2014;Chen, Chen, Gao, Yang, & Yan, 2015;Ying & Xu, 2017). Similar to Haberman, Lee, and Whitney (2015), we are aware that the 'attractiveness unit' is arbitrary, and we do not mean that the (perceived) attractiveness differences between the testing faces are strictly linear.…”