Nissani, M., Hoefler-Nissani, D., Lay, U T., & Htun, U W. (2005).
Simultaneous visual discrimination in Asian elephants.
Journal of the Experimental Analysis of Behavior, 83, 15-29.
Two experiments explored the behavior of 20 Asian elephants (Elephas aximus)
in simultaneous visual discrimination tasks. In Experiment 1, 7 Burmese logging
elephants acquired a white+/black- discrimination, reaching criterion in a mean
of 2.6 sessions and 117 discrete trials, whereas 4 elephants acquired a
black+/white- discrimination in 5.3 sessions and 293 trials. One elephant
failed to reach criterion in the white+/black- task in 9 sessions and 549
trials, and 2 elephants failed to reach criterion in the black+/white- task
in 9 sessions and 452 trials. In Experiment 2, 3 elephants learned a
large/small transposition problem, reaching criterion within a mean of
1.7 sessions and 58 trials. Four elephants failed to reach criterion
in 4.8 sessions and 193 trials. Data from both the black/white and
large/small discriminations showed a surprising age effect, suggesting
that elephants beyond the age of 20 to 30 years either may be unable to
acquire these visual discriminations or may require an inordinate number
of trials to do so. Overall, our results cannot be readily reconciled
with the widespread view that elephants possess exceptional intelligence.
Key words: simultaneous visual discrimination, age effect, cognition,
visual acuity, box removal, lid removal, Asian elephants