Perceptual processing during divided attention across and within visual hemifields S Walter, C Keitel, M Müller |
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Institute for Psychology, University of Leipzig, Germany
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| According to the different-hemifield advantage, responses to stimuli distributed across the two hemifields are faster and more precise than responses to stimuli that fall within one hemifield. Here we aimed to investigate this phenomenon with a divided attention paradigm. We presented six LEDs that were aligned on a semi-circle in the lower visual field, each flickering at a different frequency. Participants were asked to attend to two LEDs that were spatially separated by an intermediate LED, and to respond to simultaneous events at the attended LEDs. To perform the task they had to divide their attention within one or between both hemifields. We recorded the electroencephalogram and analysed amplitudes of continuous oscillatory brain responses, so-called steady-state visual evoked potentials (SSVEPs) that were elicited by LED flicker. SSVEP amplitudes index attentional allocation and, hence, allow inferences on the processing of individual components of multi-element displays. Only when attention had to be split across hemifields, processing of LEDs at intermittent to-be-ignored positions was significantly reduced. This finding was supported by corresponding behavioural data. Thus, results suggest that dividing attention between locations that are distributed across hemifields is easier than between locations that fall within one hemifield. |
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