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Fig. 7. The two diagrams show the frequency of occurrence of movement (M), search (S),
low tension (LT) and high tension (HT) (vertical axis) during the minute following ‘novel’
stimuli (left) and iambus-song (right). For further details see legend for Fig. 6 and text
(p. 240).
where recognition is seen as the matching of the received with the expected
stimulus.)
Secondly, one must emphasise that the two organisation systems affected
by the two lesions were not entirely contiguous with the brain damage. The
lesion groups shared some impairment characteristics. After the filter-trills
and ‘novel’ stimuli both groups showed more search, but later less high ten-
sion than sham-controls.
Thirdly, there were two categories of behavioural response to the test sti-
muli, the one shown by the posterior the other by the anterior group. After
a test stimulus the posterior group showed a long approach and search period;
the next phase was dominated by high tension components. The anterior
group showed a shorter period of approach and search to fewer stimuli; they
retreated sooner and showed low tension iɪɪ the next phase and thereafter.
Fourthly,∙.there weje secondary characteristics that separated the two le-
sion groups. These depended on the nature of the test stimuli. Where the
properties of the test stimulus were closest to the train-trills (i.e. filter-trills)
the anterior group showed more behavioural changes. Where there was mes-
sage content to the test stimulus, the posterior group showed more behaviour-
al changes. Correlated with this reaction of the posterior group to T2(6)S> was
a higher level of high tension.
Lastly, there were two control measures that gave an approximate indica-
tion of the degree of generalisation arid habituation to repeated stimulus pre-