Re:TheAshLad - Sandbooks

direction. Mental rotation of shapes. A truly enormous number of
proposals have been made on what is. lateral ized in the brain (see
Allen for a readable summary).At the. broadest level these theories fall
into two groupsspecialization. theories propose unique functions for
each hemisphereand interaction. theories propose cooperation between
the two hemispheres.. Several authors (for exampleEfron)have
suggested that it is not. motor control itself that is located in the left
hemisphere but rather. the capacity for the fine resolution of stimuli in
time.In other. wordsbecause the analysis and production of speech
require fine. discrimination over very short intervalsthe left hemisphere
might be. specialized for temporal sequencing (organizing be havior or.
information or both over time).Elaborations of this idea have stressed.
the capacity of the left hemisphere to make fine discriminations in.
timewhether or not the stimuli are verbal (seefor.
exampleSergent).Recall the study of Morsecode operators discussed.
earlierthere is a lefthemisphere advantage even though the code is. not
verbal it is a temporal sequence. Zatorre and his colleagues. expanded
the Efron timing idea by emphasizing that speech and musical. sounds
exploit different acoustical cuesspeech is highly dependent on. rapidly
changing broadband soundswhereas tonal pat terns of music. tend to be
sloweralthough small and precise changes in fre quency. are
important.Zatorre proposed that the auditory cortices in the two.
hemispheres are therefore specialized such that temporal resolution is.
better in the left and spectral resolution is better in the right. auditory
areas.. Rather than specifying different processing of specified.
psychological processesother specialization models focus on the. idea
that the two hemispheres might process information in distinctly.
different ways.. The first clear proposal of different information
processing was. made by Josephine Semmes in .On the basis of the
results of her. previous studies of World War II veterans suffering from
penetrating. brain injuriesSemmes concluded that the left hemisphere
functions as. a collection of focalized regionswhereas the right
hemisphere. functions more diffusely. To account for these
differencesSemmes. argued that a person with a small lesion in the right
hemisphere. exhibits no deficitsbecause specific functions are not
localized in. discrete regions in the right hemispherethe functions being
diffusely. represented.A large lesion of the right hemisphere produces
many more. deficits than would be predicted from the total of smaller
lesions. because an entire functional field is removed.A large lesion of
the. left hemisphere produces many deficits simply because many small
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