Monkeys choose, but do not learn, through exclusion

Human children will select a novel object from among a group of known objects when presented with a novel object name. This disambiguation by exclusion may facilitate new name-object mappings and may play a role in the rapid word learning shown by young children. Animals including dogs, apes, monkeys, and birds make similar exclusion choices. However, evidence regarding whether children and nonhuman animals learn new associations through choice by exclusion is mixed. In the present study we dissociate choice by exclusion from learning by exclusion in rhesus monkeys using a paired-associate task. In experiment 1, monkeys demonstrated choice by exclusion by choosing a novel comparison image from among known comparison images when presented with a novel sample image. In experiment 2, monkeys failed to benefit from choice by exclusion in learning new sets of paired associates. Monkeys learned new sets of four paired associates by trial and error alone or by a combination of exclusion and trial and error. Despite choosing correctly by exclusion on almost 100% of opportunities, monkeys did not learn any faster by exclusion than by trial and error alone. These results indicate that monkeys chose, but do not learn, through exclusion, highlighting the importance of separately evaluating choice and learning in studies of exclusion in word learning.