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Abstract:
An increasing consensus views the phenomenon of extinction as
due to a failure of attention rather than to a sensory failure. The
study of Baylis, Driver & Rafal (1993; JCN, 5, 453) provides
clear evidence to contradict a sensory explanation. In this study
it was found that subjects missed more stimuli in the
contralesional field on double simultaneous stimulation (DSS)
trials when this contralesional stimulus was the same as that in
the ipsilesional field. Such a result provides clear evidence that
stimuli in both fields must be processed at least to a featural
level. If stimuli in the contralesional field were not processed on
DSS trials, then clearly the nature of that stimulus could not
affect extinction. Considerable debate has centered around the
phenomenon of extinction in the auditory and tactile modalities,
particularly as to whether these represent failures of attention or
sensation. Despite the fact that visual extinction is generally
thought of as an attentional phenomenon, many researchers assert
that tactile extinction may represent sensory gating of
contralesional information. In order to address this issue we use
the technique of Baylis et al (1993) on auditory and tactile
extinction. We found that the relationship between the stimuli in
the two fields can modulate extinction, leading to the conclusion
that extinction is an attentional phenomenon in all three
modalities.
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