Feature-based attentional modulation of orientation perception in somatosensation.

Meike A Schweisfurth,Stefan Treue,Renate Schweizer

doi:10.3389/fnhum.2014.00519

Abstract

In a reaction time study of human tactile orientation detection the effects of spatial attention and feature-based attention were investigated. Subjects had to give speeded responses to target orientations (parallel and orthogonal to the finger axis) in a random stream of oblique tactile distractor orientations presented to their index and ring fingers. Before each block of trials, subjects received a tactile cue at one finger. By manipulating the validity of this cue with respect to its location and orientation (feature), we provided an incentive to subjects to attend spatially to the cued location and only there to the cued orientation. Subjects showed quicker responses to parallel compared to orthogonal targets, pointing to an orientation anisotropy in sensory processing. Also, faster reaction times (RTs) were observed in location-matched trials, i.e., when targets appeared on the cued finger, representing a perceptual benefit of spatial attention. Most importantly, RTs were shorter to orientations matching the cue, both at the cued and at the uncued location, documenting a global enhancement of tactile sensation by feature-based attention. This is the first report of a perceptual benefit of feature-based attention outside the spatial focus of attention in somatosensory perception. The similarity to effects of feature-based attention in visual perception supports the notion of matching attentional mechanisms across sensory domains.

Highlights

Due to the brain’s limited processing capacity, human perception cannot provide a complete representation of the sensory input from the environment
We explored the behavioral effects of tactile spatial and feature-based attention in a human reaction time paradigm, using orientation as the relevant stimulus dimension
After cueing one of two locations and one of two orientations at the beginning of each block of trials, the subjects had to monitor two simultaneous sequences of oblique tactile distractors presented to the two fingers and react as soon as a target orientation was presented at one of the fingers (Figure 2)

Summary

Introduction

Due to the brain’s limited processing capacity, human perception cannot provide a complete representation of the sensory input from the environment. Our brain combines this external, bottom-up sensory information with internal, top-down influences to selectively enhance the processing and perception of information that we assume to be relevant. Voluntary attention is the major top-down influence for this selection process. It can lead to improved processing of attended locations, objects, and features, such as decreased reaction times (RTs) and higher accuracy rates for attended compared to unattended sensory signals (e.g., Posner, 1978). Attention seems to enhance the integrated saliency (Treue, 2003) such as the perceived contrast and size of stimuli (Carrasco et al, 2004; Anton-Erxleben et al, 2007). While attentional effects have been extensively studied in the visual domain, far less research has been devoted to somatosensory attention (for an overview, see Mueller and Giabbiconi, 2008)

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Discussion

Conclusion