Comparative performance in discrimination learning tasks in two New World primates (Saimiri sciureus and Callicebus moloch)

Abstract

Squirrel monkeys (Saimiri sciureus) and titi monkeys (Callicebus moloch) were tested in three two-choice visual discrimination experiments. Although, on average, squirrel monkeys performed more accurately than titis, the range of response accuracies in the two species overlapped considerably in all three experiments and changes in response accuracy over test sessions and across experiments were similar in the two species. Thus, the species shared several behavioral characteristics expected of New World primates in this setting. Squirrel monkeys' performance appeared to be more affected than titis' by task difficulty, and squirrel monkeys were individually less consistent than titis. These differences were associated with higher activity levels and briefer overt attentiveness to the repetitive task in squirrel monkeys and, conversely, with lower activity levels, slower working speeds, and sustained interest in the task in titis. The associated differences are discussed in relation to each species performance in other laboratory settings and the characteristic patterns of foraging and use of space in nature. © 1981 Psychonomic Society, Inc.