Meredith J. West - US grants

Major discoveries about how birds learn to sing have brought to light remarkable parallels with how human beings learn to speak. Just as human beings learn to speak the language that is spoken around them, many species of birds learn to sing the song that is sung by their neighbors. Just as human speech develops from infant babbling, bird song develops from simpler vocalizations of young birds. Drs. West and King have discovered that this development of song by male cowbirds is guided by visual signals from female cowbirds, just as signals from other people guide the development of speech by the human child. This important discovery of social shaping of vocal repertoires is the basis for the current research project, which will explore linkages between female perception and male vocal production in the development of avian communicative capacities. The species chosen for study, the brown-headed cowbird, is especially appropriate because it can be bred in captivity, affording the opportunity to study the development of individuals with known communicative histories. This research should lead to the delineation of new forms of non- imitative vocal learning, the elucidation of how reward mechanisms function in a naturally-occurring form of cultural transmission, and the investigation of how the visual system operates at behavioral and neural levels to affect vocal development.

9722865 West/King The aim of the proposed research is to explore the role of different kinds of sensory experience on the ontogeny of avian communication, with a focus on reproductive skills and underlying neuroanatomical structures. Three objectives are outlined, using an avian model. First, the influence of adult stimulation on juvenile learners will be examined in a series of longitudinal studies. Measures of the effects of experience include vocal growth, vocal imitation, use of vocal signals, visual attention, and reproductive skills. Second, characteristics of female perception will be studied with special emphasis on modifiability of female mating preferences. New evidence suggests contextual influences on female preferences. Measures of preference include female responsiveness to auditory playback and female discrimination of potential mates. Finally, neural studies of the avian forebrain are planned to exploit new findings on females' use of song nuclei and males' use of a visual thalamic nucleus. The results of the proposed work should advance knowledge of the nature of developmental organization of vocal and perceptual learning and the integration of behavioral and neural plasticity. Finally, the neural analyses should broaden our understanding of the role of forebrain structures by revealing interdependencies between patterns of neural growth and availability of relevant ecological experience.

Meredith J. West: The role of social organization on development and learning

Lay abstract

The aim of the proposed research is to explore the effects of social organization on avian learning and to find developmental principles to guide research on vocal communication in other groups, including humans. Of special interest is how animals, when living in an information-rich environment, selectively attend, interact, and learn from other members of their species. Given that they do not or cannot learn equally from all individuals, what rules guide access and attention to social information?

Interest in the origins and nature of social organization stems from an interest in expanding the study of learning and development toward ecological concerns. It is proposed that much species-typical knowledge is delivered via social networks, social groups in which older organisms or peers facilitate or constrain exposure to information. The idea of networks has been bypassed in most laboratory research on learning because generally the animals are simply exposed to stimulation delivered with minimal species-typical context.

To study socially guided learning, higher-level patterns of social organization are to be investigated. These are patterns that result from flock dynamics, yielding different developmental effects for mature and immature males and females. To explore about such effects, birds are studied throughout the year in large aviaries in which the composition of groups is periodically altered and the effects measured. Social and vocal behavior is recorded, mate choice tests employed, and eggs collected and incubated to measure production, fertility, and viability. In addition, blood will be taken for DNA analyses. These procedures afford the chance to explore adaptive effects on communicative competence as a function of opportunities for social learning. The work is focused on questions regarding causation and function. First, are there simple rules to guide social assortment, and how does social organization affect learning? Second, how do specific behavioral traits, beyond age or sex, affect formation of groups and how do such groups affect developmental trajectories of individuals?

The proposed work has far-reaching implications for understanding complex communication systems, including the human communication system. In recently completed work with human parents and their infants, hypotheses were tested by us about prelinguistic vocal plasticity based on avian models of social learning. It was found that infant babbling could be socially shaped by parental responses. Parents did not vocally imitate infants' sounds, thus ruling out vocal matching as a mechanism. These are the first data to show such a relationship and they challenge long standing but untested ideas about the innate nature of early speech development. Thus, the proposed avian studies provide a new set of heuristic principles with which to formulate research questions on ecological approaches to vocal learning in many animals, as well as related phenomena such as human prelinguistic development.

Within humans it is widely recognized that early differences in personality shape the development of behavior. For instance, extraverts commonly seek out interactions with unfamiliar individuals, while introverts consistently seek out interaction with fewer more familiar individuals. Thus, personality may shape an individual's behavioral development by exposing them to different social experiences from an early age. Recently there has been increasing awareness that like humans, animals also possess personality traits. The proposed research will investigate how variation in a personality trait, sociability, shapes behavioral development in Brown-headed Cowbirds (Molothrus ater). Cowbirds, like many other species, rely on social interaction in order to learn new skills and behaviors. Sociability describes an individual's tendency to seek out interaction with others. More sociable cowbirds will approach and interact with more individuals more often than less sociable cowbirds. Two studies will investigate if: 1) Variation in sociability predicts the development of adult like behavior in juvenile cowbirds, and 2) if early experience with more or less sociable adults shapes the development of juvenile personality traits. A new RFID based video system will be used in both studies to identify individuals and record their social behaviors over long periods of time. This system will allow measurement of the details of sociability and social behavior in a way that was unavailable to researchers before. Statistical time series models can be implemented to uncover how an individual's sociability reflects the development of new behaviors over the first year of life. In the second experiment, statistical time series models will be used to uncover if experience with more sociable adults can predict the emergence of adult-like behavior within a juvenile cowbirds' first year. These results will provide insights into how early personality differences shape the development of behavior by determining how individuals interact and learn from others.

Data will be stored and available at http://datadryad.org/