Human analog tests of object permanence were administered to various breeds of adult dogs (Canis familiaris). Experiment 1 showed that the performance of terriers, sporting, and working dogs did not differ. Dogs succeeded in solving invisible displacement problems, but performance was lower than in visible displacement tests. Familiarity with the task had some influence because invisible displacement tests were more successful if they were preceded by visible displacement tests. In Experiment 2, odor cues from the target object and the hiding screens were available or were masked. Results confirmed that success was lower in invisible than in visible displacement tests and that these problems were solved on the basis of representation of visual information rather than on the basis of olfactory cues or of local rule learning. Dogs are compared with other species that display Stage 6 object permanence.

This article addresses the issue of the communication of emotion by actors. In Study 1, the facial behavior of 6 actors portraying emotions as felt or unfelt were analyzed with the Facial Action Coding System. Results indicated that the portrayals of felt emotions were closer to the expression of genuine emotion than the portrayals of unfelt emotions for 3 of the 6 emotions under investigation. Study 2 examined the decoding of actors' portrayals from facial behavior. Decoders were found to be very accurate in recognizing the emotional category but not in judging the encoding condition.

During the last IS years, Piagel's theory and methods have been used to investigate the cognitive capacities and development of nonhuman primates as well as of a few avion and mammalian species. Most studies have focused on formal testing of object permanence, but data are also available on sensory-motor intelligence, on the concepts of space and causality, and on imitation. Some primate studies have tested concrete-operational prerequisites and skills (conservation, classification, and sedation). Methodological flaws and conceptual ambiguities prevent any firm conclusion on the cognitive capacities of some species studied. Reliable data are available on such mammalian carnivores as cats, dogs, and wolves, and various studies confirm the close similarity between ape and human sensory-motor development. There are also indications that great-ape intelligence develops beyond this point, and chimpanzees display basic elements of symbolic representation. In this article, we assess the heuristic value and the limits of the Piagetian approach in terms of its contribution to the analysis of animal cognitive development and to comparative psychology.In the last decade, the problem of animal mind has reappeared in the literature. This problem, which was a central concern of early post-Darwinian scientists (Burghardt, 1985;Demarest, 1983;Wasserman, 1984), was nearly abandoned after World War I, with the increasing influence of radical behaviorism. A number of events, including the decline of stimulusresponse theories and the "identity crisis" of comparative psychology (Demarest, 1980), have contributed to its reappearance.Recent studies of animal mind originate from various fields of research and theoretical frameworks: comparative neuropsy-

Cats' and dogs' search behavior was compared in different problems where an object was visibly moved behind a screen that was then visiblymoved to a new position. In Experiments 1 (cats) and 2 (dogs), one group was tested with identical screens and the other group was tested with dissimilar screens. Results showed that in both species, search behavior was based on processing of spatial information rather than on recognition of the visual features of the target screen. Cats and dogs were unable to find the object by inferring its invisible movement. They reached a high level of success only if there was direct perceptual evidence that the object could not be at its initial position. When the position change was indicated by an indirect cue, cats searched more at the object's initial than [mal position, whereas dogs searched equally at both positions. Interspecific similarities and differences are interpreted in terms of the requirements for resetting working memory.

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Administered tests of object permanence to in order to assess as accurately as possible the developmental level reached at each age group in this Piagetian cognitive capacity. The results indicate that 28-day-old kittens visually tracked a moving object in their perceptual field (Stage 2); 35-day-nlds recovered a hidden object only if they had initiated a search movement at the time of disappearance (Stage 4a); 48-and 150-dayolds mastered multiple visible displacements (Stage 5b). The study showed that the upper limit, Stage 5b, observed in adult cats was reached by Day 48, which indicates a rapid development of object permanence in this species. Results are discussed in relation to object permanence in human babies and in terms of the relevance of object permanence to predatory behavior in the domestic cat.This article reports portions of a doctoral dissertation submitted by Claude Dumas to Universite Laval, Eeole dc psychologic, Quebec, Quebec, Canada, in partial fulfillment of the requirements for the doctoral degree. This research was supported by Grant A 7030 from the Natural Sciences and Engineering Research Council of Canada (NSERC) and Grant EQ-2760 from Fonds Formation de Chercheurs et Aide a la Recherche du Gouvernement du Quebec (FCAR) to Francois Y. Dore. During his graduate studies Claude Dumas was also supported by NSERC and FCAR.We wish to thank MoniqueComeau, Nicole Perreault, and Marline Thibault for their assistance in collecting data. We also wish to thank Paul Harris for his helpful comments on a first version of this article.

The aim of the experiment was to study the relation between accuracy of judgment of facial expressions of emotions and time for judgment. The results for 34 college students confirmed previous data showing high performance in identification of all emotions, although there were some important differences between emotions. Also, times for judgment were longer for the emotions which were more difficult to identify.

Visual accommodation and object permanence tests were administered to 70 puppies (Canis familiaris), aged 4 weeks to 9 months. The results showed that understanding of visible displacement problems emerged at the 5th weeks and developed rapidly until the 8th week. Although the search behaviors of older puppies were more flexible, no further significant development was observed between 8 weeks and 9 months. The results on invisible displacement tests suggest that understanding of invisible displacement problems appears around the 1st year in dogs' development.