Call combinations in monkeys: compositional or idiomatic expressions?

Syntax is widely considered the feature that most decisively sets human language apart from other natural communication systems. Animal vocalisations are generally considered to be holistic with few examples of utterances meaning something other than the sum of their parts. Previously, we have shown that male putty-nosed monkeys produce call series consisting of two call types in response to different events. They can also be combined into short sequences that convey a different message from those conveyed by either call type alone. Here, we investigate whether ‘pyow-hack’ sequences are compositional in that the individual calls contribute to their overall meaning. However, the monkeys behaved as if they perceived the sequence as an idiomatic expression rather than decoding the sequence. Nonetheless, while this communication system lacks the generative power of syntax it enables callers to increase the number of messages that can be conveyed by a small and innate call repertoire.     

Measuring reaction time and controlling the video display in experiments on an IBM PC

The problems of using the IBM PC XT/AT or their clones in experiments are recognized because of the slow, inadequate and awkward timing procedures of these microcomputers. Some specific solutions to these problems are described, including a compiled BASIC approach using real time procedures accurate to 1 millisecond (although resolution to 1 microsecond can be achieved) and synchronization of the video display with the program. Programs are available from the authors on receipt of a 5 1/4 inch floppy disc or $10.     

Early social experience and responses to visual social stimuli in young monkeys

Juvenile stumptailed macaques (Macaca arctoides) were given preference tests in which they could approach an empty chamber, a mirror, a familiar conspecific, or an unfamiliar conspecific. Control subjects tended to withdraw from the mirror, and threatened the stranger more than did monkeys whose early social experience had occurred exclusively in darkness. Both groups explored the familiar stimulus animal most of all, but the group socialized in the dark showed most positive behavior when in the empty chamber. In a second study peer-reared infants responded more appropriately to slides of conspecifics than did infants reared with a mirror as the main source of social input. Infants reared only with a peer were also strongly attracted to a mirror, whereas infants reared only with mirrors preferred a film of an unfamiliar agemate. The results suggest that early visual social stimulation is important in the development of aggression and other social behaviors, and that novelty and complexity are important aspects of social stimuli that interact with effects of early experience. Study 2 was conducted while the first author was in receipt of a Postgraduate Research Studentship from the U.K. Science Research Council. The DTU tapes were analyzed using a computer program developed with the help of SRC grant B/RG 98910 to A. Chamove. This latter grant also supported the study from which the preference test data were taken.