Patients with apraxia are more impaired when performing transitive
pantomimes than intransitive gestures. This dissociation might
be related to the differences in movement complexity.
Alternatively, the programs for intransitive gestures might
be better defined, more widely distributed, or easier to activate
than are those for transitive pantomimes. The purpose of this
study was to test the complexity versus representational
hypotheses. Twenty right-handed normal subjects both performed
and discriminated correct from incorrect transitive pantomimes
and intransitive gestures. The discrimination was performed
by having subjects point at illustrations of hand postures.
The subjects performed better when discriminating postures than
when performing gestures or pantomimes. On both the production
and discrimination tests, subjects performed better with
intransitive gestures than transitive pantomimes. Although the
finding that even normal subjects had more difficulty performing
transitive pantomimes than intransitive gestures might appear
to support the complexity hypothesis, that subjects also had
more difficulty discriminating transitive than intransitive
postures supports the representational activation hypothesis.
(JINS, 2002, 8, 958–963.)