The present thesis addresses the cross-modal plasticity occurring in the visual
modality due to profound deafness. In Chapter 1, we review the current perspective on
the general mechanisms of cross-modal plasticity and, in particular, the changes
occurring in visual modality in the case of profound deafness. Enhanced visual abilities
in the deaf have typically been reported when in tasks that involve visual attention
resources and processing of peripheral portions of the visual field. In this thesis, we
present a series of four experimental studies aimed at specifying which visual
attentional components display modulations in case of deafness. In Chapter 2 and 3, we
contrasted the role of endogenous and exogenous capture of visual attention. The results
showed that endogenous attention, when tested in a transient-free context, does not
reveal compensations effects due to deafness (i.e., enhancement). By contrast, enhanced
performance for peripheral portion of the visual field emerged when exogenous capture
of selective attention was involved. We suggest that enhanced visual performance in the
deaf is transients selective. In Chapter 4, we contrasted the ability to simply react to a
visual event (simple detection task) and the ability to orient visual attention (shape
discrimination task). The results showed that deaf posses marked enhanced reactivity
compared to hearing controls, when detecting targets presented at both central and
peripheral locations. Reactivity is thus an enhanced visual skill in the deaf that is not
spatially selective, in the sense that it does not emerge solely at peripheral locations. In
addition, RTs results support the hypothesis that deaf may display a different neural
representation of the peripheral portion of the visual field. These effects were not paired
by enhanced ability to discriminate between different shapes regardless of their relative
position, suggesting that enhanced reactivity was not due to a better mechanism of 6
attention orienting. Finally, in Chapter 5, we present the electrophysiological data
recorded during a simple visual detection task. The ERPs analysis revealed that
deafness determines quantitative and qualitative modulations of visual processing
already at the early stages (C1, P1). Finally, Chapter 6 resumes and discusses the
implications of the overall set of results.
| Identifer | oai:union.ndltd.org:unitn.it/oai:iris.unitn.it:11572/369211 |
| Date | January 2008 |
| Creators | Bottari, Davide |
| Contributors | Bottari, Davide |
| Publisher | Università degli studi di Trento, place:trento |
| Source Sets | Università di Trento |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | firstpage:1, lastpage:178, numberofpages:178 |
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