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 […]

The Use of Analogous Reasoning for Assessing Discomfort in Laboratory Animals

When assessing discomfort in animals analogous reasoning is often used, namely, that the causes or symptoms of discomfort in people will also apply to animals. This practical rule of thumb can be based on an ‘analogy-postulate’. This postulate takes into account the anatomical and physiological similarities of vertebrate nervous systems and the comparability and homology […]

Relational Matching in Baboons (Papio papio) With Reduced Grouping Requirements

Analogical reasoning is a corner stone of human cognition, but the phylogenetic origins of this skill are still unknown. Recent animal studies have suggested that only apes can solve the 2- by 2-item relational matching (RMTS) analogy problem, with potential benefits of language- (Premack, 1983) or token-training procedures (Thompson, Oden, & Boysen, 1997). In this […]