Chimpanzee Responding During Matching to Sample: Control by Exclusion

Abstract

Three chimpanzees performed a computerized matching-to-sample task in which samples were photographs of items and comparison stimuli were geometric symbols called lexigrams. In Experiment 1, samples were either defined (i.e., they represented items that were associated already with a specific lexigram label by the chimpanzees) or undefined (i.e., they did not have an already learned association with a specific lexigram). On each trial, the foil (incorrect) comparison could be either a defined or an undefined lexigram. All 3 chimpanzees selected the correct comparison for undefined samples at a level significantly better than chance only when the foil comparison was defined. In Experiment 2, three comparisons were presented on each trial, and in Experiment 3, four comparisons were presented on each trial. For Experiments 2 and 3, the foil comparisons consisted of either defined or undefined comparisons or a mixture of both. For these two experiments, when the chimpanzees were presented with an undefined sample, they typically made selections of only undefined comparisons. These data indicate that the chimpanzees responded through use of exclusion. A final experiment, however, indicated that, despite the use of exclusion to complete trials with undefined samples correctly, the chimpanzees did not learn new associations between undefined samples and comparisons.

Monkeys choose, but do not learn, through exclusion

“…Additionally, performance on exclusion trials in Experiment 2 remained high even after monkeys had seen the to-be-excluded pair thousands of times such that they were no longer truly novel. These results are consistent with findings of robust choice by exclusion in humans, chimpanzees, dogs, and sea lions (Beran, 2010;Beran & Washburn, 2002;Kaminski et al, 2004;Kastak & Schusterman, 2002;Markson & Bloom, 1997;Pilley & Reid, 2011;Tomonaga, 1993).…”

“…A chimpanzee selected a novel lexigram from among known lexigrams when presented with a picture or verbal label for a novel to-be-named item, but showed no retention of pairs selected on these trials (Beran, 2010;Beran & Washburn, 2002). Chaser, a border collie, correctly selected novel toys when presented with novel verbal labels, but showed no retention of these word-item pairs after 24 hrs (Pilley & Reid, 2011).…”

“…For example, trained dogs have learned verbal labels for large sets of toys (Kaminski et al, 2004;Pilley & Reid, 2011) and language trained chimpanzees have a vocabulary of well-known lexigram images associated with specific items such as food, toys, and familiar people (Beran, 2010;Beran & Washburn, 2002). In choice by exclusion tests, a novel word (dogs) or lexigram (chimpanzees) is followed by presentation of a novel target item among familiar distracter items.…”

“…Both the dogs and the chimpanzees correctly select the novel items when presented with a novel label, and do not select the novel item when presented with a familiar label, indicating choice governed by exclusion rather than novelty alone (Beran, 2010;Beran & Washburn, 2002;Kaminski et al, 2004;Pilley & Reid, 2011). However, only one dog showed retention of a small number of mappings chosen through exclusion over even a short delay (correct selection of 4/6 new mappings; Kaminski et al, 2004), the other dog and the chimpanzees showed no retention (Beran, 2010;Beran & Washburn, 2002;Pilley & Reid, 2011). This suggests that, as in human children, proficiency in choice by exclusion in nonhumans does not necessarily result in learning.…”

Remembering past exchanges: Apes fail to use social cues

“…Specifically, if they learn that object type A is bound to Experimenter 1, and object type B is bound to Experimenter 2, would they assume that object type C should be bound to Experimenter 3? We know that primates and other species are able to infer by exclusion using causal and spatial-temporal information (see Beran & Washburn, 2002;Völter & Call, 2017), but it is less clear if they can do so with more abstract information, such as social information.…”