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Wiegand, Iris; Finke, Kathrin ORCID: 0000-0001-8546-7141; Töllner, Thomas ORCID: 0000-0001-5399-9952; Starman, Kornelija; Müller, Hermann J. ORCID: 0000-0002-4774-5654; Conci, Markus ORCID: 0000-0002-3403-0318 (December 2015): Age-related decline in global form suppression. In: Biological Psychology, Vol. 112: pp. 116-124
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Abstract

Visual selection of illusory ‘Kanizsa’ figures, an assembly of local elements that induce the percept of a whole object, is facilitated relative to configurations composed of the same local elements that do not induce a global form—an instance of ‘global precedence’ in visual processing. Selective attention, i.e., the ability to focus on relevant and ignore irrelevant information, declines with increasing age; however, how this deficit affects selection of global vs. local configurations remains unknown. On this background, the present study examined for age-related differences in a global-local task requiring selection of either a ‘global’ Kanizsa- or a ‘local’ non-Kanizsa configuration (in the presence of the respectively other configuration) by analyzing event-related lateralizations (ERLs). Behaviorally, older participants showed a more pronounced global-precedence effect. Electrophysiologically, this effect was accompanied by an early (150–225 ms) ‘positivity posterior contralateral’ (PPC), which was elicited for older, but not younger, participants, when the target was a non-Kanizsa configuration and the Kanizsa figure a distractor (rather than vice versa). In addition, timing differences in the subsequent (250–500 ms) posterior contralateral negativity (PCN) indicated that attentional resources were allocated faster to Kanizsa, as compared to non-Kanizsa, targets in both age groups, while the allocation of spatial attention seemed to be generally delayed in older relative to younger age. Our results suggest that the enhanced global-local asymmetry in the older age group originated from less effective suppression of global distracter forms on early processing stages—indicative of older observers having difficulties with disengaging from a global default selection mode and switching to the required local state of attentional resolution.