Abstract: Previous research suggests that when a fixed interval is interrupted (known as the gap procedure), pigeons tend to reset memory and start timing from 0 after the gap. However, because the ambient conditions of the gap typically have been the same as during the intertrial interval (ITI), ambiguity may have resulted. In the present experiment, the authors found that when ambient conditions during the gap were similar to the ITI, pigeons tended to reset memory, but when ambient conditions during the gap were different from the ITI, pigeons tended to stop timing, retain the duration of the stimulus in memory, and add to that time when the stimulus reappeared. Thus, when the gap was unambiguous, pigeons timed accurately.

Abstract: In this study we examined how social learning of feeding preferences by zebra finches was affected by the identity of different demonstrators. We presented adult zebra finches with two demonstrators, one male and one female, that exhibited different food choices, and we recorded their subsequent preference when given a choice between the two food types. Previously it was found that young zebra finches' patterns of social learning are affected by the sex of the individual demonstrating a feeding behaviour. This result could be explained by the lack of exposure these animals had to the opposite sex, or by their mating status. Therefore, we investigated the social learning preferences of adult mated zebra finches. We found the same pattern of directed social learning of a different type of feeding behaviour (food colour): female zebra finches preferred the colour of food eaten by male demonstrators, whereas male zebra finches showed little evidence of any preference for the colour of food eaten by female demonstrators. Furthermore, we found that female observers' preferences were biased by demonstrators' relative feeding activity: the female demonstrator was only ever preferred if it ate less than its male counterpart.

Abstract: Males in multi-male groups of chacma baboons (Papio hamadryas ursinus) in Botswana compete for positions in a linear dominance hierarchy. Previous research suggests that males treat different categories of rivals differently; competitive displays between males of similar rank are more frequent and intense than those between disparately ranked males. Here we test whether males also respond differently to male-male interactions in which they are not directly involved, using playbacks of the loud 'wahoo' calls exchanged between competing males in aggressive displays. We played paired sequences of vocal contests between two adjacently ranked and two disparately ranked males to ten subjects, half ranking below the signalers in the call sequences and half above. Subjects who ranked above the two signalers showed stronger responses than lower-ranking subjects. Higher-ranking subjects also responded more strongly to sequences involving disparately ranked, as opposed to adjacently ranked opponents, suggesting that they recognized those individuals' relative ranks. Strong responses to sequences between disparately ranked opponents might have occurred either because such contests typically involve resources of high fitness value (defense of meat, estrous females or infants vulnerable to infanticide) or because they indicate a sudden change in one contestant's condition. In contrast, subjects who ranked lower than the signalers responded equally strongly to both types of sequences. These subjects may have been able to distinguish between the two categories of opponents but did not respond differently to them because they had little to lose or gain by a rank reversal between males that already ranked higher than they did.

Abstract: Seven experiments were conducted on four miniature pigs to determine: (1) whether the pigs can discriminate between people wearing the same coloured clothing; (2) what cues they rely on if they could discriminate. For 2 weeks before the experiments began, the pigs were conditioned in a Y-maze to receive raisins from the rewarder wearing dark blue coveralls. They were then given the opportunity to choose the rewarder or non-rewarder in these experiments. Each session consisted of 20 trials. Successful discrimination was that the pig chose the rewarder at least 15 times in 20 trials (P<0.05: by χ2-test). In Experiment 1, both rewarder and non-rewarder wore dark blue coveralls. By 20 sessions, all pigs successfully identified the rewarder. In Experiment 2: (1) both wore coveralls of the same new colours or (2) one of them wore coveralls of new colours. They significantly preferred the rewarder even though the rewarder and/or non-rewarder wore coveralls of new colours. In Experiment 3, both wore dark blue coveralls but olfactory cues were obscured and auditory cues were not given. The pigs were able to identify the rewarder successfully irrespective of changing auditory and olfactory cues. In Experiment 4, both wore dark blue coveralls but covered part of their face and body in different ways. The correct response rate decreased when a part of the face and the whole body of the rewarder and non-rewarder were covered. In Experiment 5, both wore dark blue coveralls and changed their apparent body size by shifting sitting position. The correct response rate increased as the difference in body size between the experimenters increased. In Experiment 6, the distance between the experimenters and the pig was increased by 30 cm increments. The correct response rate of each pig decreased as the experimenters receded from the pig, but performance varied among the pigs. In Experiment 7, the light intensity of the experimental room was reduced from 550 to 80 lx and then to 20 lx. The correct response rate of each pig decreased with the reduction in light intensity, but all the pigs discriminated the rewarder from the non-rewarder significantly even at 20 lx. In conclusion, the pigs were able to discriminate between people wearing coveralls of the same colour after sufficient reinforcement. These results indicate that pigs are capable of using visual cues to discriminate between people.

Abstract: The evaluation of important parameters for measuring the horses’ cognitive capacities is one of the central topics of the equine behaviour team at Nürtingen-Geislingen University. Social complexity has been said to be one of the settings in which needs for cognitive capacities arise in animals. A variety of studies throughout the last two decades proved the horses’ social complexity to be far more elaborate than previously assumed. Horses form social bonds for the protection of offspring, intervene in encounters of others, identify group mates individually and easily orientate in a fission fusion society.
In such socially complex societies, animals will benefit from learning socially. In many bird and primate species the degree of social complexity correlates nicely with the species abilities for social learning. Social learning was, therefore, argued to be an indicator for elaborate mental capacities in animals. We were delighted to prove that horses actually copy social behaviour and techniques for operating a feeding apparatus from older and higher ranking group members. In a recent study we found young horses, at the age of 3 to 12, to copy the operation of a feeding apparatus from a human demonstrator. Social learning seems to work nicely in horses when the social background of the animals is considered.
The degree to which individual animals adapt to changes in their social or physical environment by finding innovative solution appears to be the other side of the coin, of whether animals adjust to challenges by social learning. It is not very astonishing, that along with the animals’ social complexity and their ability to learn socially also the degree to which they show innovative behaviour was claimed to be one of the most important demonstrations of advanced cognitive capacities. In a recent approach, we started to ask horse owners and horse keepers in many countries to tell us about unusual behaviour of their horses via a web site (http://innovative-behaviour.org). To date, we received 204 cases of innovative behaviour descriptions from which six cases were clear examples of tool use or borderline tool use. We categorized the innovative behaviours into the classes, a) innovations to gain food, b) innovations to gain freedom, c) social innovations, d) innovations to increase maintenance, and e) innovations that could not be clearly assigned to a category. About 20% of the innovative horses showed more than one innovation. These animals could be termed “true innovators”. Again, young horses were more innovative than older ones with the age group 5 – 9 showing the highest number of innovative behaviour descriptions.
In a nutshell, the horses’ cognitive capacities appear to be underestimated throughout the last decades. The horses’ social complexity is far more elaborate than previously assumed, horses learn socially from conspecific and humans, some of them demonstrate innovative behaviour adaptations to their environment and even simple forms of tool use.