Young and juvenile chimpanzees' (Pan troglodytes) reactions to intentional versus accidental and inadvertent actions.

Chimpanzees were tested for their ability to discriminate between accidental/inadvertent and intentional actions with equivalent adverse consequences. Subjects were first trained to `point' to human trainers in order to receive food rewards. In Experiment 1, six 5-year-old subjects were alternately presented with two unfamiliar human actors. In condition 1, each actor either started to hand a cup of juice to the trainer but then pulled it back and intentionally poured it onto the floor, or accidentally spilled it while handing it to the trainer. In condition 2, the actors either accidentally spilled it as above, or aggressively threw the juice onto the floor. The subjects were then presented with both actors and were allowed to choose between them. In Experiment 2, seven 6-7-year-old chimpanzees were confronted with unfamiliar actors who either (a) intentionally withheld and consumed food intended for the subjects, (b) attempted to hand the intended food to the subjects but were victimized by a third party who consumed the food, or (c) always succeeded in delivering the food to the subjects. In general, the subjects showed little evidence of using the accidental/inadvertent versus intentional distinction in their choices between the actors, although they did display some evidence of favoring the actor involved in the most passive role in both conditions in Experiment 1.