Effects of spatial and feature attention on disparity-rendered structure-from-motion stimuli in the human visual cortex.

Ifan Betina Ip,Holly Bridge,Andrew J Parker

doi:10.1371/journal.pone.0100074

Ifan Betina Ip, Holly Bridge + Show 1 more

Open Access

https://doi.org/10.1371/journal.pone.0100074

Copy DOI

Abstract

An important advance in the study of visual attention has been the identification of a non-spatial component of attention that enhances the response to similar features or objects across the visual field. Here we test whether this non-spatial component can co-select individual features that are perceptually bound into a coherent object. We combined human psychophysics and functional magnetic resonance imaging (fMRI) to demonstrate the ability to co-select individual features from perceptually coherent objects. Our study used binocular disparity and visual motion to define disparity structure-from-motion (dSFM) stimuli. Although the spatial attention system induced strong modulations of the fMRI response in visual regions, the non-spatial system’s ability to co-select features of the dSFM stimulus was less pronounced and variable across subjects. Our results demonstrate that feature and global feature attention effects are variable across participants, suggesting that the feature attention system may be limited in its ability to automatically select features within the attended object. Careful comparison of the task design suggests that even minor differences in the perceptual task may be critical in revealing the presence of global feature attention.

Highlights

Allocation of attention can modulate the responses of neurons whose stimulus selectivity is similar to the attended feature [1,2,3]
Human functional magnetic resonance imaging studies suggest a ‘global feature attention’ effect in visual cortex, which enhances the response to similar features even when presented in different locations in the visual field [5,6]
Cortical Activity Maps of Spatial Attention Significantly higher BOLD activity in the retinotopic visual cortex was generated by presenting two structure-from-motion cylinders disambiguated by binocular disparity compared to a baseline composed of two fields of static, zero-disparity dots

Summary

Introduction

Allocation of attention can modulate the responses of neurons whose stimulus selectivity is similar to the attended feature [1,2,3]. The feature similarity gain model [4] summarizes these results: enhancement when attending to the preferred feature of a neuron and suppression for the opposite. Direction of attention to specific features of a complex visual stimulus implies that observers can select out and respond to one stimulus component. This contrasts with cue combination, in which information from different features is brought together to form the most accurate estimate of the surface profile of the object. One example is the Bayesian combination of stereo and texture or luminance cues, in which the variance of the perceptual estimate of surface shape is reduced by exploiting information from more than one source [7,8]

Methods

Results

Discussion

Conclusion