Song learning of songbirds provides us a unique opportunity to study detailed mechanisms for vocal learning in various species, including humans. Recent studies in the behavioral neuroscience field have shown accumulated evidence indicating that their song learning is based on reinforcement via the auditory feedback of their own voice. The present review introduces an experimental paradigm that can elicit additional learning in bird's songs as a response to perturbations in the auditory feedback with noise presentation. This paradigm, named the noise-avoidance (NA) experiment, is quite useful for understanding the mechanism for song learning. Here I summarize findings obtained from the NA experiments, and review the current understanding of behavioral and neuroscientific mechanisms for feedback-based vocal learning. Additionally, I discuss computational aspects of the NA behavior in light of the reinforcement learning framework, and how the NA paradigm can be associated with the operant conditioning.
We introduce a unique art-science collaboration project organized by contemporary artists and comparative psychologists at Kyoto City Zoo in 2019. The objectives of this project were to evaluate how chimpanzees and humans respond to movies created by professional artists and to contribute to an outreach event at the zoo by demonstrating the entire research process to the public. We asked the artists to make short movies 'for chimpanzees' and presented those movies to chimpanzee and human participants while tracking the participants' eye movements using an eye-tracker. Both chimpanzees and humans looked at similar elements of movies, such as appearance of animal figures, targets of actions, and the center of abstract concentric figures. The differences between chimpanzees and humans were also pronounced; for example, human showed strong 'center bias' by keeping their gaze around the center of the screen, while chimpanzee did so to a lesser extent. This study not only offered comparative knowledge about responses to (artistic) movies in chimpanzees and humans but demonstrated how non-scientists can learn comparative psychology through an outreach project.
Altruistic behaviour, such as allogrooming and allofeeding, has been suggested to be crucial for maintenance of cooperative relationship especially between non-kin individuals. Monogamous pair-bond, which is widespread in birds, is a form of cooperation for breeding between a male and a female. Many previous studies reported that altruistic behaviour within pair-bonds occurred primarily from males to females. However, most of those findings were obtained from the observations during the breeding season, and therefore it remains unknown what sex-different patterns of altruistic behaviour occur outside the breeding season for life long monogamous birds. The present observation study investigated sex differences of altruistic behaviour within pair-bonds outside the breeding context in a life-long monogamy, large-billed crows (Corvus macrorhynchous). Specifically, frequency of allopreening and allofeeding were compared between sexes and also between pair-bonds. We found that frequency of both behaviour was different between sexes, and inconsistent within and between pair-bonds. Our findings suggest that altruistic behaviour within pair-bonds may occur asymmetrically between sexes but vary between pair-bonds in large-billed crows.
The present study examined effects of retention and intertrial intervals on proactive interference in the eight-arm radial maze performance in rats. A trial consisted of a forced choice of four arms in a learning phase, retention interval, and a free choice among eight arms in a test phase. In Experiment 1, rats were given two daily trials with 10 s or 1 min. retention intervals between the learning and the test phases and with 5, 30, or 60 min. intertrial intervals. In the 1 min. retention condition, proactive inference indexed by decline in performance from the first trial to the second trial was observed regardless of intertrial intervals. In contrast, such decline in performance was not observed for all the intertrial interval conditions in the 10 s retention condition. In Experiment 2, rats were tested with a 1 min. retention interval and 5 or 120 min. intertrial intervals. Significant proactive interference was observed again for a 5 min. intertrial interval condition replicating the results of Experiment 1. In contrast, proactive interference was eliminated completely by lengthening the intertrial interval to 120 min. These results suggest that discriminability among memories in current and prior trials in terms of elapsed time is a determinant of proactive interference in the radial maze performance in rats.
Here we discuss the origins of diversity in social behavior by highlighting research using the socially monogamous prairie vole. Prairie voles display a rich social behavioral repertoire involving pair bonding and consoling behavior that are not observed in typical laboratory species. Oxytocin and vasopressin play critical roles in regulating pair bonding and consoling behavior. Oxytocin and vasopressin receptors show remarkable diversity in expression patterns both between and within species. Receptor expression patterns are associated with species differences in social behaviors. Variations in receptor genes have been linked to individual variation in expression patterns. We propose that "evolvability" in the oxytocin and vasopressin receptor genes allows for the repurposing of ancient maternal and territorial circuits to give rise to novel social behaviors such as pair bonding, consoling and selective aggression. We further propose that the evolvability of these receptor genes is due to their transcriptional sensitivity to genomic variation. This model provides a foundation for investigating the molecular mechanisms giving rise to the remarkable diversity in social behaviors found in vertebrates.
Many studies suggest that cooperation in human societies has been achieved via peer interactions such as reward and punishment. As the group size is larger, however, it is difficult to maintain cooperation only by peer interactions. Instead, a centralized punishment system such as police governs large-scale societies and cooperation is maintained. In this paper, first, I explain why peer interactions have limitations to achieve large-scale cooperation and why centralized punishment system, which often includes social hierarchy, has superiority. Second, I discuss how social hierarchy can be formed and maintained. Considerable evidence indicates that hierarchy in humans is principally based both on dominance (coercive capacity based on strength and threat) and prestige (persuasive capacity based on skills, abilities, and knowledge). Some researchers argue that non-human animals also form hierarchy based on dominance, but only humans form stratification based on prestige. After introducing their argument, I would like to discuss how humans (and other animals) form hierarchy and achieve cooperation.