Abstract: Squirrel monkeys (Saimiri sciureus) and capuchin monkeys (Cebus apella) were tested using an expectancy violation procedure to assess whether they use an actor's gaze direction, signaled by congruent head and eye orientation, to predict subsequent behavior. The monkeys visually habituated to a repeated sequence in which the actor (a familiar human or a puppet) looked at an object and then picked it up, but they did not react strongly when the actor looked at an object but then picked up another object. Capuchin monkeys' responses in the puppet condition were slightly more suggestive of expectancy. There was no differential responding to congruent versus incongruent look-touch sequences when familiarization trials were omitted. The weak findings contrast with a strongly positive result previously reported for tamarin monkeys. Additional evidence is required before concluding that behavior prediction based on gaze cues typifies primates; other approaches for studying how they process attention cues are indicated.

Abstract: Autoren
B. Agnetta, B. Hare, M. Tomasello
Zusammenfassung
The results of three experiments are reported. In the main study, a human experimenter presented domestic dogs (Canis familiaris) with a variety of social cues intended to indicate the location of hidden food. The novel findings of this study were: (1) dogs were able to use successfully several totally novel cues in which they watched a human place a marker in front of the target location; (2) dogs were unable to use the marker by itself with no behavioral cues (suggesting that some form of human behavior directed to the target location was a necessary part of the cue); and (3) there were no significant developments in dogs' skills in these tasks across the age range 4 months to 4 years (arguing against the necessity of extensive learning experiences with humans). In a follow-up study, dogs did not follow human gaze into “empty space” outside of the simulated foraging context. Finally, in a small pilot study, two arctic wolves (Canis lupus) were unable to use human cues to locate hidden food. These results suggest the possibility that domestic dogs have evolved an adaptive specialization for using human-produced directional cues in a goal-directed (especially foraging) context. Exactly how they understand these cues is still an open question.
Schlüsselwörter
Key words Dogs – Arctic wolves – Social cognition – Gaze following – Communication

Abstract: Most birds rely on imprinting and experience with conspecifics to learn species-specific recognition cues. Australian brush-turkeys (Alectura lathami) do not imprint and form no bonds with parents. They hatch asynchronously, disperse widely and meet juvenile conspecifics at an unpredictable age. Nevertheless, in captivity, hatchlings respond to other chicks. A recent study, which involved the use of robotic models, found that chicks prefer to approach robots that emit specific visual cues. Here, we evaluated their response to acoustic cues, which usually play an important role in avian social cognition. However, in simultaneous choice tests, neither 2-day-old nor 9-day-old chicks preferred the choice arm with playback of either chick or adult conspecific calls over the arm containing a silent loudspeaker. Chicks of both age classes, however, scanned their surroundings more during chick playback, and the response was thus consistent in younger and older chicks. We also presented the chicks with robotic models, either with or without playback of chick calls. They did not approach the calling robot more than they did the silent robot, indicating that the combination of visual and acoustic cues does not evoke a stronger response. These results will allow further comparison with species that face similar cognitive demands in the wild, such as brood parasites. Such a comparative approach, which is the focus of cognitive ecology, will enable us to further analyse the evolution and adaptive value of species recognition abilities.

Abstract: Horses have been considered to rely on human gesticular cues (McKinley and Sambrook 2000, Anim Cogn 3:13-22; and recently Maros et al. 2008, Anim Cogn 11:457-466), however large variability among individuals tested in two-ways object choice tasks was found. Part of the horses in those studies (40 and 26 %, respectively) even failed to pass adequately through the training session which preceded the testing phase and served to learn a horse to carry out a task. Therefore, we alternated the experimental design designed by McKinley and Sambrook (reduced number of testing trials to 10 per horse to keep its attention, applied just one, a dynamic-sustained pointing cue with touching the bucket, etc.), and tested an effect of training method, sex, age, and learning on proportion of correct choices. We hypothesised, that horses trained by “traditional” method (TTM) will get lower score than those experienced with “horsemanship-based” methods (HTM), being characterized by closer and more frequent human-horse contact and also extended exercising “from the ground” with frequent using of arms cues. Despite simplification of the methods, only about 60 % of tested horses passed through the training phase (i.e., learned to come to and upturn the bucket with hidden treat). Successful completion of training phase was reached regardless of age or sex of a horse, but by the training method; HTM horses ran better compared to TTM ones. No significant effect of age, sex, or learning (i.e., trial order within all 10), and training method as well was found on proportion of correct trials in the testing phase. Horses made a correct choice in more than 70% of trials. Individual scores ranged from 50 to 100 %. In conclusion, horses showed high level of comprehension of human pointing gesture, regardless of their sex or age. No effects of training method or learning process within a test suggest low impact of handling and learning on the level of comprehension at least of the most vivid human pointing gesture. Horses trained by methods based on “natural human-horse communication” did enhance cooperation with people.

Abstract: The Sir Philip Sidney game has been used by numerous authors to show how signal cost can facilitate honest signaling among relatives. Here, we demonstrate that, in this game, honest cost-free signals are possible as well, under very general conditions. Moreover, these cost-free signals are better for all participants than the previously explored alternatives. Recent empirical evidence suggests that begging is energetically inexpensive for nestling birds; this finding led some researchers to question the applicability of the costly signaling framework to nestling begging. Our results show that cost-free or inexpensive signals, as observed empirically, fall within the framework of signaling theory.