Stimulus- and state-dependence of systematic bias in spatial attention: Additive effects of stimulus-size and time-on-task

Christopher S.Y. Benwell, Monika Harvey, Stephanie Gardner, Gregor Thut (Lead / Corresponding author)

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

Systematic biases in spatial attention are a common finding. In the general population, a systematic leftward bias is typically observed (pseudoneglect), possibly as a consequence of right hemisphere dominance for visuospatial attention. However, this leftward bias can cross-over to a systematic rightward bias with changes in stimulus and state factors (such as line length and arousal). The processes governing these changes are still unknown. Here we tested models of spatial attention as to their ability to account for these effects. To this end, we experimentally manipulated both stimulus and state factors, while healthy participants performed a computerized version of a landmark task. State was manipulated by time-on-task (>1 h) leading to increased fatigue and a reliable left- to rightward shift in spatial bias. Stimulus was manipulated by presenting either long or short lines which was associated with a shift of subjective midpoint from a reliable leftward bias for long to a more rightward bias for short lines. Importantly, we found time-on-task and line length effects to be additive suggesting a common denominator for line bisection across all conditions, which is in disagreement with models that assume that bisection decisions in long and short lines are governed by distinct processes (Magnitude estimation vs Global/local distinction). Our findings emphasize the dynamic rather than static nature of spatial biases in midline judgement. They are best captured by theories of spatial attention positing that spatial bias is flexibly modulated, and subject to inter-hemispheric balance which can change over time or conditions to accommodate task demands or reflect fatigue.

Original languageEnglish
Pages (from-to)827-836
Number of pages10
JournalCortex
Volume49
Issue number3
Early online date3 Jan 2012
DOIs
Publication statusPublished - 1 Jan 2013

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Keywords

  • Alertness
  • Cross-over
  • Landmark task
  • Orienting
  • Pseudoneglect

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