Examination of behavioral inhibition across contexts in rhesus monkeys

K. Coleman1,2, R. Clark1, R.E. Dahl2, N.D. Ryan2 and J.L. Cameron1,2

1Oregon Regional Primate Research Center, Beaverton, OR, U.S.A.
2Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, U.S.A.

Behavioral inhibition, a construct of temperament broadly defined in terms of response to novelty, has been measured across a wide variety of species by investigators in several fields. The various tests used to measure behavioral inhibition differ in the type of novel stimulus that is presented, the degree of fearful stimulus they include, and whether a fearful stimulus is social or nonsocial. Surprisingly, there has been little examination of the level of concordance among such tests. We compared behavior in response to four tests commonly used to measure behavioral inhibition in 44 young rhesus macaques living in large groups in outdoor enclosures.

The tests used were:

We found that these composite scores did not correlate across tests (inhibited: W=0.26, p>0.2; fearful: rs=-0.17, p>0.2). For example, monkeys that explored the novel room in the freeplay test did not show increased propensity to inspect the fruit in the novel fruit test (rs=-0.03, p>0.5). And, monkeys that showed fear towards the car were not more likely to show fear during the human intruder test. In addition to these composite scores, we also compared individual variables across tests.

We conclude that context is very important in the measurement of behavioral inhibition. Moreover, choice of a test for behavioral inhibition should be based on the aspect of this measure that the investigator is interested in (low exploration, elevated anxiety or fear to a nonsocial stimulus, etc.). This principle We conclude that context is very important in the measurement of behavioral inhibition. Moreover, choice of a test for behavioral inhibition should be based on the aspect of this measure that the investigator is interested in (low exploration, elevated anxiety or fear to a nonsocial stimulus, etc.). This principle will be particularly important when determining correlations between behavioral inhibition and specific physiological measures.

References

  1. Kalin, N.H.; Shelton, S.E. (1989). Defensive behaviors in infant rhesus monkeys: environmental cues and neurochemical regulation. Science, 243, 1718-1721.

Poster presented at Measuring Behavior 2000, 3rd International Conference on Methods and Techniques in Behavioral Research, 15-18 August 2000, Nijmegen, The Netherlands

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