Abstract: Pigeons were trained to peck a certain number of times on a key that displayed one of several possible numerical symbols. The particular symbol displayed indicated the number of times that the key had to be pecked. The pigeons signalled the completion of the requirement by operating a separate key. They received a food reward for correct response sequences and time-out penalties for incorrect response sequences. In the first experiment nine pigeons learned to allocate 1, 2, 3 or 4 pecks to the corresponding numerosity symbols s1, s2, s3 and s4 with levels of accuracy well above chance. The second experiment explored the maximum set of numerosities that the pigeons were capable of handling concurrently. Six of the pigeons coped with an s1-s5 task and four pigeons even managed an s1-s6 task with performances that were significantly above chance. Analysis of response times suggested that the pigeons were mainly relying on a number-based rather than on a time-based strategy.

Abstract: We analysed, under laboratory test conditions, how German cockroach larvae oriented their outgoing foraging trip from their shelter. Our results stressed the importance of external factors, like availability and spatial distribution of food sources, in the choice of a foraging strategy within their home range. When food sources were randomly distributed, larvae adopted a random food search strategy. When food distribution was spatially predictable and reliable, cockroaches were able to relate the presence of food with a landmark during a 3-day training period and to develop an oriented search strategy. Cockroaches were able to associate learned spatial information about their home range to the presence of food resources and then to improve their foraging efficiency. However, conflict experiments revealed that detection of food odour overrode learned landmark cues.

Abstract: Despite earlier scepticism there is now evidence for simple forms of intentional and functionally referential communication in many animal species. Here we investigate whether dogs engage in functional referential communication with their owners. “Showing” is defined as a communicative action consisting of both a directional component related to an external target and an attention-getting component that directs the attention of the perceiver to the informer or sender. In our experimental situation dogs witness the hiding of a piece of food (or a favourite toy) which they cannot get access to. We asked whether dogs would engage in “showing” in the presence of their owner. To control for the motivational effects of both the owner and the food on the dogs' behaviour, control observations were also staged where only the food (or the toy) or the owner was present. Dogs' gazing frequency at both the food (toy) and the owner was greater when only one of these was present. In other words, dogs looked more frequently at their owner when the food (toy) was present, and they looked more at the location of the food (toy) when the owner was present. When both the food (toy) and the owner were present a new behaviour, “gaze alternation”, emerged which was defined as changing the direction of the gaze from the location of the food (toy) to looking at the owner (or vice versa) within 2 s. Vocalisations that occurred in this phase were always associated with gazing at the owner or the location of the food. This behaviour, which was specific to this situation, has also been described in chimpanzees, a gorilla and humans, and has often been interpreted as a form of functionally referential communication. Based on our observations we argue that dogs might be able to engage in functionally referential communication with their owner, and their behaviour could be described as a form of “showing”. The contribution of domestication and individual learning to the well-developed communicative skills in dogs is discussed and will be the subject of further studies.

Abstract: Most birds and mammals learn characteristics of conspecifics from their parents and siblings. In interspecific brood parasites, however, early social learning could lead to species recognition errors because young are reared among heterospecifics. Conceivably, juvenile parasites might inspect and memorize aspects of their own phenotype, and later match features of encountered individuals to that template. We tested for such self-referent phenotype matching by manipulating feather colors of hand-reared fledglings (n = 21) of the parasitic brown-headed cowbird (Molothrus ater). In simultaneous choice trials (n = 6 trials/subject) between dyed and normal-colored adult females, juvenile cowbirds (< 2 months old) approached more quickly and associated preferentially with individuals that were colored similar to themselves. These preferences remained even when differences between the associative behaviors of juvenile males and females were controlled statistically. Our data imply that cowbirds incorporate their own plumage color into their recognition template. This provides the first evidence of self-referent phenotype matching through experimental manipulation of a recognition cue.

Abstract: In an attempt to increase the reliability of the demonstrator-consistent responding effect produced in the bidirectional control procedure, experiments 1-4 sought conditions that would magnify the matching effect. The aim was to produce a robust demonstrator-consistent responding effect in order that future analytic experiments could investigate the psychological processes responsible for this effect. The joystick responses of observer rats trained using the standard bidirectional control procedure parameters were compared with those of observers subject to conditions identified in the social learning literature as favourable for imitation. Unlike mice, observer rats in experiments 1 a and 1 b tended to push a joystick in the same direction as their demonstrators when the demonstrators were either familiar or unfamiliar males and females. Comparable demonstrator-consistent responding occurred following observation of a standard and a salient joystick response (experiment 2). Experiment 3 showed that the discriminative accuracy of a demonstrator's responding was important for matching behaviour, and suggested that matching might be enhanced with more than the conventional single observation session. Experiment 4 confirmed that the bidirectional control effect is sensitive to the amount of observational experience; after six observation sessions, demonstrator-inconsistent responding occurs. The results of experiments 1-3 are, and those of experiment 4 are not, compatible with the hypothesis that demonstrator-consistent responding in the bidirectional control is caused by olfactory cues deposited by demonstrators on the joystick.