Duration of dogs' (Canis familiaris) working memory in search for disappearing objects

Abstract

Two experiments explored the duration of dogs' working memory in an object permanence task: a delay was introduced between the disappearance of a moving object behind a box and the beginning of the search by the animal. In experiment 1, the dogs were tested with retention intervals of 0, 10, 30, and 60 s. Results revealed that the dogs' accuracy declined as a function of the length of the retention interval but remained above chance for each retention interval. In experiment 2, with new subjects, longer retention intervals (0, 30, 60, 120, and 240 s) were presented to the dogs. Results replicated findings from experiment 1 and revealed that the dogs' accuracy remained higher than chance level with delays up to 240 s. In both experiments, the analysis of errors also showed that the dogs searched as a function of the proximity of the target box and were not subject to intertrial proactive interference. In the discussion, we explore different alternatives to explain why dogs' search behaviour for hidden objects decreased as a function of the retention intervals.

Domesticated dogs' (Canis familiaris) use of the solidity principle

“…The breed composition of our sample (as reported by the owners) included one pug, one Australian shepherd, one Catahoula, one golden retriever, and six dogs of mixed breeds. Our sample size of ten dogs falls within the wide range of sample sizes often employed by others exploring dogs' cognitive abilities (e.g., Topál et al 2006;Osthaus et al 2005;Fiset et al 2003;Miklósi et al 1998). …”

“…This disappearance is problematic because the organism must maintain a representation of the object in memory, as well as generate an expectation about where it will later appear (Hauser 2001). Humans and a variety of non-human animals (e.g., gorilla-Gorilla gorilla gorilla, Japanese macaque-Macaca fuscata, African Grey parrot-Psittacus erithacus, domesticated dogs-Canis familiaris) can maintain representations of hidden objects over time (e.g., Piaget 1952;Natale et al 1986;Doré and Dumas 1987;Pepperburg and Funk 1990;Baillargeon and DeVos 1991;Gagnon and Doré 1992;Fiset et al 2003). However, the factors underlying predictive reaching, searching, and looking for objects that have become hidden from view are not well understood, especially in organisms other than humans and non-human primates.…”

“…Studies have also begun to reveal how other species represent objects (e.g., Pepperberg and Kozak 1986;Goulet et al 1994;Funk 1996;Pepperberg et al 1997;Pollock et al 2000;Cooper et al 2003;Fiset et al 2003Collier-Baker et al 2004;Mendes and Huber 2004;Fiset and Doré 2006;Zucca et al 2007;Miklósi 2007;Miller et al 2009;Whitt et al 2009;Deppe et al 2009). Indeed, such explorations could provide new insights into tasks with human and non-human primate populations.…”

A memória de um gesto comunicativa humano no cão doméstico (Canis familiaris)

“…O grupo de Sylvain Fiset é que mais tem investigado em cães a memória operacional em contextos espaciais (FISET et al, 2000;FISET et al, 2003;FISET et al, 2006;FISET, 2007;FISET, 2009 …”

“…Animais podem transpor intervalos de retenção conservando algo da postura inicial diante do estímulo apropriado, no meio de outros -direção do corpo, da cabeça, dos olhos, etc., (HUNTER, 1913) ou então mantendo sua atenção sobre este estímulo, não perdendo-o de vista, por assim dizer -e dispor assim de um lembrete capaz de gerar escolha sem grande recurso à memória (GAGNON & DORÉ, 1993;VALLORTIGARA et al, 1998). A colocação de um anteparo, logo depois da sinalização (FISET et al, 2003;GAGNON & DORÉ, 1993) abole a dica do contato visual e também torna menos provável o uso da dica postural. Os cães, mesmo presos pela guia, mudavam de postura durante o intervalo e a manutenção do nível de acerto, no Experimento II, depois da aplicação de eventos de distração como atender a comandos ou até deslocar-se para fora do contexto experimental imediato, reforça a conclusão de que o desempenho observado não decorre de manutenção postural, mas, sim, da memória.…”