Same/Different Concept Learning by Capuchin Monkeys in Matching-to-Sample Tasks

Abstract

The ability to understand similarities and analogies is a fundamental aspect of human advanced cognition. Although subject of considerable research in comparative cognition, the extent to which nonhuman species are capable of analogical reasoning is still debated. This study examined the conditions under which tufted capuchin monkeys (Cebus apella) acquire a same/different concept in a matching-to-sample task on the basis of relational similarity among multi-item stimuli. We evaluated (i) the ability of five capuchin monkeys to learn the same/different concept on the basis of the number of items composing the stimuli and (ii) the ability to match novel stimuli after training with both several small stimulus sets and a large stimulus set. We found the first evidence of same/different relational matching-to-sample abilities in a New World monkey and demonstrated that the ability to match novel stimuli is within the capacity of this species. Therefore, analogical reasoning can emerge in monkeys under specific training conditions.

Effects of brief time delays on matching-to-sample abilities in capuchin monkeys (Sapajus spp.)

“…In Experiment 1, 0-delay trials were intermixed with trials of a less demanding, condition (i.e. SMTS), with which the monkeys were already familiar from their experience in previous studies [30,40]. By contrast,0-delay trials were intermixed with unfamiliar, more demanding, conditions (i.e.…”

“…1 ), two males (Sandokan and Robot) and three females (Pippi, Roberta and Rucola). All subjects were adults (age range: All monkeys were already familiar with the Simultaneous MTS procedure because they had been tested with a touchscreen based apparatus in tasks involving categorisation of visual stimuli and abstract concept acquisition [30,40]. Moreover, one monkey, Pippi, had been previously trained on tasks involving visual pattern discrimination (e.g., [41,42]).…”

Analogical reasoning in baboons (Papio papio): Flexible reencoding of the source relation depending on the target relation

“…Thus, a first set of studies showed that baboons (Fagot, Wasserman, & Young, 2001), and then pigeons (Cook & Wasserman, 2007), can solve this task when the relations are illustrated by arrays of multiple stimuli rather than by pairs of items. In addition, recent studies have revealed that nonhuman primates can pass the RMTS task with pairs of items rather than arrays after extensive training on the task (in a capuchin, Truppa, Mortari, Garofoli, Privitera, & Visalberghi, 2011;in baboons, Fagot & Parron, 2010;Fagot & Thompson, 2011) or with specific reinforcement contingencies (Flemming, Thompson, Beran, & Washburn, 2011). Vonk (2003) further reported relational matching in a gorilla and orangutans with limited training.…”

“…Previous RMTS tasks used with animals have only manipulated a single stimulus dimension at a time, such as the shape (e.g., Fagot & Thompson, 2011;Truppa et al, 2011) or color (e.g., Fagot & Parron, 2010) of the stimuli. With these procedures, inspection of the source stimuli provided all the cues necessary to determine the (same or different) relation to be processed, with no need to reencode the source domain in terms of the properties of the target domain.…”

“…Humans would have no real difficulty associating these pairs during an analogy task, because the items within each pair have something in common, independent of the dimension (shape, color, or function) shared by these items. Unfortunately, that ability to match relations across dimensions cannot be tackled by the version of RMTS procedure used so far with animals, again because these tasks only imply the processing of a single dimension at a time (e.g., the shape dimension, Fagot & Thompson, 2011;Truppa et al, 2011; or the color dimension, Fagot & Parron, 2010). Empirical data are needed in this domain to evaluate the power and flexibility of analogical thinking in animals.…”