Hemispheric asymmetries in categorical perception of orientation in infants and adults

Franklin, Anna, Catherwood, Dianne F, Alvarez, James and Axelsson, Emma (2010) Hemispheric asymmetries in categorical perception of orientation in infants and adults. Neuropsychologia, 48 (9). pp. 2648-2657. doi:10.1016/j.neuropsychologia.2010.05.011

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Abstract

Orientation CP is the faster or more accurate discrimination of two orientations from different categories (e.g., oblique1 and vertical1) compared to two orientations from the same category (e.g., oblique1 and oblique2), even when the degree of difference is equated across conditions. Here, we assess whether there are hemispheric asymmetries in this effect for adults and 5-month-old infants. Experiment 1 identified the location of the vertical-oblique category boundary. Experiment 2, using a visual search task with oriented lines found that adult search was more accurate when the target and distractors were from different orientation categories, compared to targets and distractors of an equivalent physical difference taken from the same category. This effect was stronger for targets lateralized to the left visual field (LVF) than the right visual field (RVF), indicating a right hemisphere (RH) bias in adult orientation CP. Experiment 3, replicated the RH bias using different stimuli and also investigated the impact of visual and verbal interference on the category effect. Experiment 4, using the same visual search task, found that infant search was also faster when the target and distractors were from different orientation categories than the same, yet this category effect was stronger for RVF than LVF lateralized targets, indicating a LH bias in orientation CP at 5 months. These findings are contrasted to equivalent studies on the lateralization of color CP (e.g., Gilbert, Regier, Kay, & Ivry, 2005). The implications for theories on the contribution of the left and right hemispheres of the infant and adult brain to categorical computations are discussed.

Item Type:	Article
Article Type:	Article
Uncontrolled Keywords:	Spatial; Category; Lateralization
Subjects:	H Social Sciences > H Social Sciences (General)
Divisions:	Schools and Research Institutes > School of Education and Science
Research Priority Areas:	Health, Life Sciences, Sport and Wellbeing
Depositing User:	Anne Pengelly
Date Deposited:	18 Aug 2015 10:40
Last Modified:	31 Aug 2023 09:05
URI:	https://eprints.glos.ac.uk/id/eprint/2513

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