Independent selection of eye and hand targets suggests effector-specific attentional mechanisms

Nina M Hanning,David Aagten-Murphy,Heiner Deubel

doi:10.1038/s41598-018-27723-4

Nina M Hanning, David Aagten-Murphy + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-27723-4

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Abstract

Both eye and hand movements bind visual attention to their target locations during movement preparation. However, it remains contentious whether eye and hand targets are selected jointly by a single selection system, or individually by independent systems. To unravel the controversy, we investigated the deployment of visual attention – a proxy of motor target selection – in coordinated eye-hand movements. Results show that attention builds up in parallel both at the eye and the hand target. Importantly, the allocation of attention to one effector’s motor target was not affected by the concurrent preparation of the other effector’s movement at any time during movement preparation. This demonstrates that eye and hand targets are represented in separate, effector-specific maps of action-relevant locations. The eye-hand synchronisation that is frequently observed on the behavioral level must emerge from mutual influences of the two effector systems at later, post-attentional processing stages.

Highlights

Previous research has shown that eye movements[1,2,3] as well as hand movements[4,5] are preceded by shifts of attention to their motor targets prior to movement onset
As the different action selection mechanisms did not compete for attentional resources at any time during movement preparation, our findings demonstrate that separate, effector-specific attentional mechanisms are responsible for selecting the motor targets for eye and hand movements
By asking our participants to perform simultaneous eye-hand movements to separate locations, we demonstrated that attention builds up at both the saccade and reach target in parallel, without any trade-off between the two motor targets

Summary

Introduction

Previous research has shown that eye movements[1,2,3] as well as hand movements[4,5] are preceded by shifts of attention to their motor targets prior to movement onset. The control of these two movement types does not seem to be independent: When we interact with objects in our environment, our eye and hand movements frequently are highly coupled, both spatially and temporally. This raises the question whether eye and hand movements are attentional selected in unison, by one common mechanism, or whether they are selected individually by independent attention systems. We investigated the deployment of visual attention – an index of motor target selection – during the simultaneous preparation of saccadic eye movements and hand movements. As the different action selection mechanisms did not compete for attentional resources at any time during movement preparation, our findings demonstrate that separate, effector-specific attentional mechanisms are responsible for selecting the motor targets for eye and hand movements

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