Abstract: Living in large, stable social groups is often considered to favour the evolution of enhanced cognitive abilities, such as recognizing group members, tracking their social status and inferring relationships among them. An individual's place in the social order can be learned through direct interactions with others, but conflicts can be time-consuming and even injurious. Because the number of possible pairwise interactions increases rapidly with group size, members of large social groups will benefit if they can make judgments about relationships on the basis of indirect evidence. Transitive reasoning should therefore be particularly important for social individuals, allowing assessment of relationships from observations of interactions among others. Although a variety of studies have suggested that transitive inference may be used in social settings, the phenomenon has not been demonstrated under controlled conditions in animals. Here we show that highly social pinyon jays (Gymnorhinus cyanocephalus) draw sophisticated inferences about their own dominance status relative to that of strangers that they have observed interacting with known individuals. These results directly demonstrate that animals use transitive inference in social settings and imply that such cognitive capabilities are widespread among social species.

Abstract: This study investigates the ability of horses to recall a feeding event in a two-point choice apparatus. Twelve horses were individually tested whereby they were maintained immobile in a test arena and visually and aurally experienced the delivery of food into one of two feed goals. The horses were then released to make their choice in two experimental contexts: immediate release after experiencing the delivery of food, and release 10 s after food delivery. Each horse performed 40 immediate-release (IR) trials, followed by forty 10-s release trials over a 3-day period. In addition, the same horses were tested 3 months later in the spring with the same number and sequence of trials. Results were analysed by log-linear analysis of frequencies. Results showed that while horses were able to achieve the correct feed goal choice in the immediate-release trials, they were unsuccessful with the 10-s release trials. This suggests that there are limitations in recall abilities in horses, in that they may not possess a prospective type of memory. There are welfare and training implications in these findings concerning the effects of overestimating the mental abilities of horses during training and the effects of delays in reinforcements.

Abstract: In mammals, olfactory cues are extensively used in many aspects of maternal care to ensure the coordination of mother-infant interactions and consequently the normal development of the offspring. Outside the period of parturition and lactation, when the young are not a behavioral priority, olfactory cues play an inhibitory role on maternal responsiveness since in most mammalian species studied so far, nonpregnant females find the odor of young aversive. On the contrary at the time of parturition, a shift in the hedonic value of infantile odors occurs so that the young now become a very potent stimulus and this sensorial processing constitutes an important part of the maternal motivational system. Moreover, infants' odors provide a basis for individual recognition by their mothers and some species (ungulates) have developed highly specialized mechanisms for processing of the infant signals. Perception of the smell of the young also regulates various aspects of maternal behavior. Dodecyl propionate, a compound released by of pup's preputial glands, has been shown to influence anogenital licking behavior, a fundamental pattern of maternal behavior in rodents. While there is no functional specificity of either the main or the accessory olfactory systems in the development of maternal behavior amongst species, it appears that only the main olfactory system is implicated when individual odor discrimination of the young is required. Neural structures, such as the main olfactory bulb, undergo profound changes when exposed to offspring odors at parturition. These changes in synaptic circuitry contribute both to maternal responsiveness to these odors, to their memorization, and to effects of long-term maternal experience.

Abstract: Domestic chicks are capable of perceiving as a whole objects partly concealed by occluders (“amodal completion”). In previous studies chicks were imprinted on a certain configuration and at test they were required to choose between two alternative versions of it. Using the same paradigm we now investigated the presence of hemispheric differences in amodal completion by testing newborn chicks with one eye temporarily patched. Separate groups of newly hatched chicks were imprinted binocularly: (1) on a square partly occluded by a superimposed bar, (2) on a whole or (3) on an amputated version of the square. At test, in monocular conditions, each chick was presented with a free choice between a complete and an amputated square. In the crucial condition 1, chicks tested with only their left eye in use chose the complete square (like binocular chicks would do); right-eyed chicks, in contrast, tended to choose the amputated square. Similar results were obtained in another group of chicks imprinted binocularly onto a cross (either occluded or amputated in its central part) and required to choose between a complete or an amputated cross. Left-eyed and binocular chicks chose the complete cross, whereas right-eyed chicks did not choose the amputated cross significantly more often. These findings suggest that neural structures fed by the left eye (mainly located in the right hemisphere) are, in the chick, more inclined to a “global” analysis of visual scenes, whereas those fed by the right eye seem to be more inclined to a “featural” analysis of visual scenes.

Abstract: An experimental study of search-image use by araneophagic jumping spiders (i.e., salticid spiders that prey routinely on other spiders) supports five conclusions. First, araneophagic salticids have an innate predisposition to form search images for specific prey from their preferred prey category (spiders) rather than for prey from a non-preferred category (insects). Second, single encounters are sufficient for forming search images. Third, search images are based on selective attention specifically to optical cues. Fourth, there are trade-offs in attention during search-image use (i.e., forming a search image for one type of spider diminishes the araneophagic salticid's attention to other spiders). Fifth, the araneophagic salticid's adoption of search images is costly to the prey (i.e., when the araneophagic salticid adopts a search, the prey's prospects for surviving encounters with the araneophagic salticid are diminished). Cognitive and ecological implications of search-image use are discussed.