Hemispheric specialisation when searching in real-world scenes: an eye-movement approach S Spotorno1, R Y Smith2, B Tatler |
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1Institut de Neurosciences de la Timone, Aix-Marseille University- CNRS, France |
| We studied the contributions of the cerebral hemispheres to real-world visual search by examining oculomotor behaviour. The target template (picture or name) was presented centrally and the scene appeared after a 100 or 900-ms ISI. The target object was lateralised in its left or right half, in order to be presented initially to the Right (RH) or the Left Hemisphere (LH), respectively. With a picture template, the first saccade was faster in the left (lvf) than in the right visual field (rvf). It was also faster with a picture than a word template, but only in the lvf, and with the long than the short ISI, mainly in the lvf. This suggests that the RH specialisation for non-verbal processes enhances promptness in eye guidance, especially with enough time to encode the target in working memory. With a word template, the first saccade was directed more often toward a lvf-target than a rvf-target. A picture template improved first saccade direction toward rvf-targets, while no template differences were found in the lvf. This indicates that only the RH can activate quickly an iconic representation of the target from its label. Overall, our results show that search initiation depends greatly on hemispheric specialisation. |
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