Generalized identity matching-to-sample in Cebus apella

UMMS Affiliation

Shriver Center

Publication Date


Document Type



Learning; Cebus


Mental and Social Health | Neuroscience and Neurobiology | Psychiatry and Psychology


Explored whether or not conditions could be created under which capuchin monkeys (Cebus apella) might display generalized identity matching-to-sample. The authors employed procedures designed to minimize the effects of several variables that past research suggested might interfere with such emergent matching. These included unwanted stimulus control by location, failure to discriminate defining stimulus features, and stimulus novelty. In Experiment 1, two monkeys displayed accurate simple simultaneous discrimination with three sets of three stimuli each, presented in any of nine locations on a touchscreen-equipped computer monitor. In Experiment 2, the same monkeys were exposed to a 0-delay identity matching training procedure involving one of the stimulus sets from Experiment 1. After the identity-matching baseline was established, identity-matching tests were presented with other three-stimulus sets. For certain sets, the critical initial identity-matching test was preceded by a history of simple discrimination reversals involving the stimuli that would appear on the test. Overall, identity-matching test scores were substantially higher than might be expected by 'chance'. In Experiment 3, two additional new stimulus sets were introduced.


Barros, R. S., Galvão, O. F., & McIlvane, W. J. (2002). Generalized identity matching-to-sample in cebus apella. The Psychological Record, 52(4), 441-460.

Journal/Book/Conference Title

The Psychological Record