The effect of situational factors on hand preferences for feeding in 177 captive chimpanzees (Pan troglodytes)

This study examined the effect of situational factors on hand use for feedi ng in a sample of captive chimpanzees. Lateral bias in hand use was tested in biased and unbiased testing circumstances to assess strength and consist ency in hand preference. For both unbiased and biased testing conditions. p opulation-level right hand preferences were found for the sample. In the bi ased condition, subjects were more likely to over-come positional factors i n order to feed with their right hand contrasted with the left. Overall, ha nd use in the biased and unbiased testing conditions was significantly posi tively correlated. In terms of strength of hand use, juveniles were found t o be less lateralized than sub-adults and adults. Moreover, juvenile female s were found to be more lateralized than juvenile males. Taken together, th e data suggest that chimpanzee hand preferences for feeding are not constra ined by situational factors and are relatively consistent in biased and unb iased testing conditions. (C) 2000 Elsevier Science Ltd. All rights reserve d.