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Rowe, M. L., & Goldin-Meadow, S. (2009). Differences in Early Gesture Explain SES Disparities in Child Vocabulary Size at School Entry. Science, 323(5916), 951–953.
Abstract: Children from low-socioeconomic status (SES) families, on average, arrive at school with smaller vocabularies than children from high-SES families. In an effort to identify precursors to, and possible remedies for, this inequality, we videotaped 50 children from families with a range of different SES interacting with parents at 14 months and assessed their vocabulary skills at 54 months. We found that children from high-SES families frequently used gesture to communicate at 14 months, a relation that was explained by parent gesture use (with speech controlled). In turn, the fact that children from high-SES families have large vocabularies at 54 months was explained by children's gesture use at 14 months. Thus, differences in early gesture help to explain the disparities in vocabulary that children bring with them to school.
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Byrne, R. W. (2009). Animal imitation. Current Biology, 19(3), R111–R114.
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Basile, M., Boivin, S., Boutin, A., Blois-Heulin, C., Hausberger, M., & Lemasson, A. (2009). Socially dependent auditory laterality in domestic horses (Equus caballus). Anim. Cogn., 12, 611–619.
Abstract: Laterality is now known to be an ubiquitous phenomenon among the vertebrates. Particularly, laterality of auditory processing has been demonstrated in a variety of species, especially songbirds and primates. Such a hemispheric specialization has been shown to depend on factors such as sound structure, species specificity and types of stimuli. Much less is known on the possible influence of social familiarity although a few studies suggest such an influence. Here we tested the influence of the degree of familiarity on the laterality of the auditory response in the domestic horse. This species is known for its social system and shows visible reactions to sounds, with one or two ears moving towards a sound source. By comparing such responses to the playback of different conspecific whinnies (group member, neighbor and stranger), we could demonstrate a clear left hemisphere (LH) preference for familiar neighbor calls while no preference was found for group member and stranger calls. Yet, we found an opposite pattern of ear side preference for neighbor versus stranger calls. These results are, to our knowledge, the first to demonstrate auditory laterality in an ungulate species. They open further lines of thought on the influence of the social “value” of calls and the listener's arousal on auditory processing and laterality.
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Bourjade, M., Thierry, B., Maumy, M., & Petit, O. (2009). Decision-making in Przewalski horses (Equus ferus przewalskii) is driven by the ecological contexts of collective movements. Ethology, 115(4), 321–330.
Abstract: We addressed decision-making processes in the collective movements of
two groups of Przewalski horses (Equus ferus przewalskii) living in a semi free-ranging population. We investigated whether different patterns of group movement are related to certain ecological contexts (habitat use and group activity) and analysed the possible decision-making processes involved. We found two distinct patterns; âsingle-boutâ and âmultipleboutâ movements occurred in both study groups. The movements were defined by the occurrence of collective stops between bouts and differed by their duration, distance covered and ecological context. For both movements, we found that a preliminary period involving several horses occurred before departure. In single-bout movements, all group members rapidly joined the first moving horse, independently of the preliminary period. In multiple-bout movements, however, the joining process was longer; in particular when the number of decision-makers and their pre-departure behaviour before departure increased. Multiplebout movements were more often used by horses to switch habitats and activities. This observation demonstrates that the horses need more time to resolve motivational conflicts before these departures. We conclude that decision-making in Przewalski horses is based on a shared consensus process driven by ecological determinants. |
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Fedurek, P., & Dunbar, R. I. M. (2009). What Does Mutual Grooming Tell Us About Why Chimpanzees Groom? Ethology, 115(6), 566–575.
Abstract: Grooming might be a resource that is offered in exchange for some benefit (e.g. access to a feeding site or coalitionary support) or it might be a mechanism for building and servicing social relationships, whose function, in turn, is to facilitate the exchange of resources and services. Bi-directional (or simultaneous mutual) grooming is unusually common among chimpanzees (though rare in other primates) and we suggest that this might be because it is an especially strong indicator of social bonding. Because the bonding role of bi-directional grooming offers substantially different predictions from the interpretation offered by the models based on reciprocal altruism (RA), we use a critical tests methodology (i.e. tests that unequivocally support one hypothesis at the expense of the other) to differentiate between the bonding and RA hypotheses. We use data on the dynamics of grooming interactions from a captive group of chimpanzees (Pan troglodytes) to show that dominant individuals tolerated the individuals with whom they performed bi-directional grooming more than they did those who typically provided them unidirectional grooming. Dominants rejected and terminated grooming sessions more often with the individuals who provided them with mostly unidirectional grooming than with those with whom they groomed bi-directionally. In addition, animals engaged in bi-directional grooming more often with both relatives and those with whom they were often in proximity. These results support the bonding model of mutually reciprocated grooming at the expense of the RA model, and suggest that, at least in chimpanzees, simultaneous mutual grooming may play a particularly important role in social bonding.
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Fureix, C., Jego, P., Sankey, C., & Hausberger, M. (2009). How horses (Equus caballus) see the world: humans as significant “objects”. Anim. Cogn., 12(4), 643–654.
Abstract: Abstract  This study aimed to determine whether horses have a kind of memory of humans (based on previous interactions), leading to a general significance of humans revealed by their reactions to humans in subsequent interactions. Subjects were 59 adult horses used to interact daily with humans. Three types of behavioural tests involving an unknown experimenter evaluated three possibly different memorized types of humanâanimal interactions (not work-related, using work-related objects, unfamiliar working task). We also performed standardized observations of routine interactions between each horse and its familiar handler (caretaker). To get a broad overview of the horsesâ reactions to humans, we recorded both investigative and aggressive behaviours during the tests, representing respectively a âpositiveâ and a ânegativeâ memory of the relationship. Whereas correlations between tests revealed a general perception of humans as either positive or negative, unusual tests, i.e. that are not usually performed, elicited more positive reactions. Moreover, some horses reacted positively to a motionless person in their box, but negatively when this same person approached them, for example for halter fitting. Overall, aggressive reactions were more reliable indicators of the relationship than positive reactions, both between tests and between familiar and unfamiliar humans. Our results also show generalization of the perception of humans. These results support our hypothesis that perception of humans by horses may be based on experience, i.e. repeated interactions. Altogether, our results support the hypothesis that horses can form a memory of humans that impacts their reactions in subsequent interactions.
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Harrison, S. A., & Tong, F. (2009). Decoding reveals the contents of visual working memory in early visual areas. Nature, 458(7238), 632–635.
Abstract: Visual working memory provides an essential link between perception and higher cognitive functions, allowing for the active maintenance of information about stimuli no longer in view1, 2. Research suggests that sustained activity in higher-order prefrontal, parietal, inferotemporal and lateral occipital areas supports visual maintenance3, 4, 5, 6, 7, 8, 9, 10, 11, and may account for the limited capacity of working memory to hold up to 3â4 items9, 10, 11. Because higher-order areas lack the visual selectivity of early sensory areas, it has remained unclear how observers can remember specific visual features, such as the precise orientation of a grating, with minimal decay in performance over delays of many seconds12. One proposal is that sensory areas serve to maintain fine-tuned feature information13, but early visual areas show little to no sustained activity over prolonged delays14, 15, 16. Here we show that orientations held in working memory can be decoded from activity patterns in the human visual cortex, even when overall levels of activity are low. Using functional magnetic resonance imaging and pattern classification methods, we found that activity patterns in visual areas V1âV4 could predict which of two oriented gratings was held in memory with mean accuracy levels upwards of 80%, even in participants whose activity fell to baseline levels after a prolonged delay. These orientation-selective activity patterns were sustained throughout the delay period, evident in individual visual areas, and similar to the responses evoked by unattended, task-irrelevant gratings. Our results demonstrate that early visual areas can retain specific information about visual features held in working memory, over periods of many seconds when no physical stimulus is present.
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John L. Orrock, & Brent J. Danielson. (2009). Temperature and Cloud Cover, but Not Predator Urine, Affect Winter Foraging of Mice. Ethology, 115(7), 641–648.
Abstract: Although homeotherms likely experience costs of both predation risk and thermoregulation while foraging, it is unclear how foragers contend with these costs. We used foraging trays placed in sheltered microsites to determine whether temperature, a direct cue of predator presence (predator urine) and an indirect cue of predation risk (cloudy nights) affect foraging of white-footed mice, Peromyscus leucopus, in winter. Mice were presented with urine from bobcats, Lynx rufus, red foxes, Vulpes vulpes, and coyotes, Canis latrans, an herbivore (whitetailed deer, Odocoileus virginianus), and a water control. To measure rodent foraging, we used seeds of millet mixed with sand to quantify giving-up densities (the number of seeds left in each foraging tray). Giving-up density was not affected by predator urine. Rather, rodent foraging was affected by an interaction of temperature and weather. On overcast nights, when predation risk was likely lower, mice foraged more when soil temperature was higher, presumably reducing thermoregulatory costs. On clear nights, foraging was low regardless of soil temperature, presumably because foraging was more risky. These results suggest that mice consider thermoregulatory costs and predation risk when making foraging decisions, and that the indirect cue afforded by weather, rather than the direct cue of predator urine, is among the cues used to make foraging decisions. Moreover, these results suggest that sensitivity to a particular cue is likely to be context-dependent.
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Ruiz, A., Gómez, J., Roeder, J., & Byrne, R. (2009). Gaze following and gaze priming in lemurs. Anim. Cogn., 12(3), 427–434.
Abstract: Abstract  Although primates have often been found to co-orient visually with other individuals, members of these same species have usually failed to use co-orientation to find hidden food in object-choice experiments. This presents an evolutionary puzzle: what is the function of co-orientation if it is not used for a function as basic as locating resources? Co-orientation responses have not been systematically investigated in object-choice experiments, and requiring co-orientation with humans (as is typical in object-choice tasks) may underestimate other speciesâ abilities. Using an object-choice task with conspecific models depicted in photographs, we provide experimental evidence that two lemur species (Eulemur fulvus, n = 4, and Eulemur macaco, n = 2) co-orient with conspecifics. Secondly, by analysing together two measures that have traditionally been examined separately, we show that lemursâ gaze following behaviour and ultimate choice are closely linked. Individuals were more likely to choose correctly after having looked in the same direction as the model, and thus chose objects correctly more often than chance. We propose a candidate system for the evolutionary origins of more complex gaze following: âgaze priming.â
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Gácsi, M., McGreevy, P., Kara, E., & Miklósi, Á. (2009). Effects of selection for cooperation and attention in dogs. Behav Brain Funct, 5, 31.
Abstract: ABSTRACT: BACKGROUND: It has been suggested that the functional similarities in the socio-cognitive behaviour of dogs and humans emerged as a consequence of comparable environmental selection pressures. Here we use a novel approach to account for the facilitating effect of domestication in dogs and reveal that selection for two factors under genetic influence (visual cooperation and focused attention) may have led independently to increased comprehension of human communicational cues. METHOD: In Study 1, we observed the performance of three groups of dogs in utilizing the human pointing gesture in a two-way object choice test. We compared breeds selected to work while visually separated from human partners (N = 30, 21 breeds, clustered as independent worker group), with those selected to work in close cooperation and continuous visual contact with human partners (N = 30, 22 breeds, clustered as cooperative worker group), and with a group of mongrels (N = 30).Secondly, it has been reported that, in dogs, selective breeding to produce an abnormal shortening of the skull is associated with a more pronounced area centralis (location of greatest visual acuity). In Study 2, breeds with high cephalic index and more frontally placed eyes (brachycephalic breeds, N = 25, 14 breeds) were compared with breeds with low cephalic index and laterally placed eyes (dolichocephalic breeds, N = 25, 14 breeds). RESULTS: In Study 1, cooperative workers were significantly more successful in utilizing the human pointing gesture than both the independent workers and the mongrels.In study 2, we found that brachycephalic dogs performed significantly better than dolichocephalic breeds. DISCUSSION: After controlling for environmental factors, we have provided evidence that at least two independent phenotypic traits with certain genetic variability affect the ability of dogs to rely on human visual cues. This finding should caution researchers against making simple generalizations about the effects of domestication and on dog-wolf differences in the utilization of human visual signals.
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