Stimulus-driven effects on line bisection behavior: An EEG study C Benwell1, M Harvey2, G Thut1 |
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1Institute of Neuroscience & Psychology, University of Glasgow, United Kingdom |
| A systematic leftward bias (pseudoneglect) is typically exhibited by healthy young adults during performance of line bisection tasks. However, the bias is modulated by stimulus factors such as line length. The processes underlying modulation of bias magnitude and direction remain unknown. A possible explanation is that bias level depends on the extent to which the spatially dominant right hemisphere is engaged by the combination of stimulus and endogenous state during performance of the task. During performance of a perceptual line bisection task in both long and short lines, we discovered long lines to induce an increased hemispheric asymmetry of electrophysiological processes implicated in visuospatial processing relative to short lines. Increased right hemisphere utilisation in long lines occurred within the P1/N1 ERP complex, and was found to correlate with line bisection bias direction/magnitude across participants. The results suggest that the common leftward bias displayed in pseudoneglect is a function of right hemisphere dominance during early stimulus-driven indices of visual processing. |
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