Size matters: Impact of item size and quantity on array choice by chimpanzees (Pan troglodytes)

The authors previously reported that chimpanzees ( Pan troglodytes ) showed a striking bias to select the larger of 2 candy arrays, despite a reversed reward contingency in which the animals received the smaller, nonselected array as a reward, except when Arabic numerals were used as stimuli. A perceptual or incentive-based interference occurred that was […]

Breeding and animal welfare: practical and theoretical advantages of multi-trait selection

The traditional concerns about farm animal welfare have centred around the impact of intensive environments and management practices on the animal. This emphasis on the physical environment is changing, however, with greater consideration being given to animal factors and in particular to the selective breeding of farm animals. In this paper we use examples from […]

Common marmoset (Callithrix jacchus) personality

Increasing evidence suggests that personality structure differs between species, but the evolutionary reasons for this variation are not fully understood. We built on earlier research on New World monkeys to further elucidate the evolution of personality structure in primates. We therefore examined personality in 100 family-reared adult common marmosets (Callithrix jacchus) from 3 colonies on […]