Figure 1.

Transfer performance of monkeys and pigeons. The monkey data are based on D’Amato et al. (1985a) and the pigeon data are based on Colombo et al. (2003). The animals were tested over four 48-trial sessions, with half of the trials dedicated to the training (old) stimuli, and half dedicated to the novel (new) stimuli. The left panel shows the transfer performance to a novel color and form stimulus (for training the monkeys were trained with two form stimuli and the pigeons trained with three form stimuli). The right panel shows the transfer performance to two novel form stimulus (for training the monkeys were trained with a color and a form stimulus, whereas the pigeons were trained with two form stimuli and a color stimulus). When the contextual variables are set appropriately for the pigeons (training with three stimuli and an FR20 on the sample), both monkeys and pigeons transfer readily to a novel color and form stimulus, but not to two novel form stimuli.