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Multiple measures of handedness
in tufted capuchin monkeys (Cebus apella).
Giovanna Spinozzi
and Valentina Truppa
Istituto di Psicologia, Consiglio Nazionale delle
Ricerche (C.N.R.), Italy
Despite the recent evidence of population-level handedness in
numerous non-human primate species, some scientists have argued
that this represents "task-specific" (i.e. laterality
across subjects but within a task), rather than "true"
handedness (i.e. laterality across subjects and across tasks),
as is the case in human beings (McGrew and Marchant, 1997), or
a "weaker" form of handedness (Coballis, 1991). In
this study, handedness data are presented for several behavioral
measures in tufted capuchin monkeys (Cebus apella). Significant
population-level hand biases were found for three out of six
unimanual measures and for two out of three bimanual tasks. Significant
positive correlation emerged across three unimanual reaching
actions and between two coordinated bimanual reaching measures.
The intercorrelation analysis suggests the existence of some
factors linked to the specific characteristics of the task to
be performed, which could influence the expression of laterality
in individual capuchins. Overall, the results seem to challenge
the account that nonhuman primate handedness reflects "task
specialization", or a "weaker" form of handedness
than human handedness.
Keywords: handedness, non-human
primates, Cebus apella, multiple-measure hand preference, within-subject
variability. |