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Abstract:
University of California, San Diego Clinical evidence
suggests that left handers have a relatively high probability
(estimated at 50-60%) of having bilateral, or reversed dominance
for language, as indexed by the presence or absence of an aphasic
deficit following unilateral brain damage. Lesion data also suggest
an important role for the right hemisphere in the comprehension of
verbal jokes. To investigate the relationship between language
lateralisation and joke comprehension in normal adults, we utilized
scalp recorded event related brain potentials (ERPs) as 7 left and
7 right handed participants read sentences for comprehension.
Stimuli included: (1) Expected Endings, such as 'Our new green car
blocked the narrow DRIVEWAY,' (2) Unexpected Straight Endings, such
as 'A replacement player hit a homerun with my BALL,' and (3)
Unexpected Joke Endings such as 'A replacement player hit a homerun
with my GIRL.' Compared to expected endings, unexpected endings
elicited a posteriorly distributed negativity 300-500 ms post-onset
(N400), and a frontally distributed positivity 500-900 ms. There
were no effects of handedness. In contrast, the comparsion of joke
and straight endings did reveal an effect of handedness and an
interaction between handedness and sentence type in ERPs measured
500-900 ms post-word onset. In both groups, Jokes elicited a slow
positive shift in this latency range. However, left handers' ERPs
were more positive, and the left handers' joke effect was larger,
more broadly distributed, and appears more laterally
symmetric.
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