Problem solving and functional design features: experiments on cotton-top tamarins, Saguinus oedipus oedipus

In any problem-solving situation, there are features associated with the pr oblem that are relevant from a functional perspective and other features th at are irrelevant. To determine whether animals are sensitive to the distin ction between functionally relevant and irrelvant features of a problem, we conducted two main experiments with a New World monkey, the cotton-top tam arin. In the first condition of both experiments, subjects were required to pull a piece of cloth to gain access to a piece of food. The first experim ent involved choosing between food that was on the cloth and food that was off the cloth. The second experiment involved choosing between food that wa s on a connected piece of cloth and food that was on two pieces of cloth se parated by a horizontal gap. Having learned to solve either of these two pr oblems, we conducted a series of probe conditions to determine whether the tamarins would generalize to changes in the shape, size, colour, and textur e of the cloth and food, the position of the food relative to the cloth, an d the type of,connection between two pieces of cloth. For most of the probe conditions, the tamarins readily generalized, showing no decrement in perf ormance, even on the first trial. For other conditions, involving apparentl y more subtle discrimination (e.g, a narrow vertical gap between the two pi eces of cloth), explicit training was required. These results indicate that tamarins solve means-end relationships, and that their ability depends on a discrimination between properties that are functionally relevant as oppos ed to irrelevant. (C) 1999 The Association for the Study of Animal Behaviou r.