The production and perception of long calls by cotton-top tamarins (Saguinus oedipus): acoustic analyses and playback experiments

The authors' goal was to provide a better understanding of the relationship between vocal production and perception in nonhuman primate communication. To this end, the authors examined the cotton-top tamarin's (Saguinus oedipus) combination long call (CLC). In Part 1 of this study, the authors carried out a series of acoustic analyses designed to determine the kind of information potentially encoded in the tamarin's CLC. Using factorial analyses of variance and multiple discriminant analyses, the authors explored whether the CLC encodes 3 types of identity information: individual, sex, and social group. Results revealed that exemplars could be reliably assigned to these 3 functional classes on the basis of a suite of spectrotemporal features. In Part 2 of this study, the authors used a series of habituation-dishabituation playback experiments to test whether tamarins attend to the encoded information about individual identity. The authors 1st tested for individual discrimination when tamarins were habituated to a series of calls from 1 tamarin and then played back a test call from a novel tamarin; both opposite- and same-sex pairings were tested. Results showed that tamarins dishabituated when caller identity changed but transferred habituation when caller identity was held constant and a new exemplar was played (control condition). Follow-up playback experiments revealed an asymmetry between the authors' acoustic analyses of individual identity and the tamarins' capacity to discriminate among vocal signatures; whereas all colony members have distinctive vocal signatures, we found that not all tamarins were equally discriminable based on the habituation-dishabituation paradigm.     

Spontaneous representation of number in cotton-top tamarins (Saguinus oedipus)

The "violation of expectancy" looking-time methodology has proven a powerful tool for exploring prelinguistic mental representations in human infants as well as in nonhuman primates. Four studies applying this methodology to the question of spontaneous number representations in cotton-top tamarins (Saguinus oedipus) are reported here. Monkeys were shown 1 + 1 events in which objects were placed behind a screen, 1 by 1. The screen was removed, revealing consistent (2 objects) and inconsistent (1, 3, or 1 large object twice the mass of original object) outcomes. In all studies, monkeys looked longer at the inconsistent than at the consistent outcome. When the monkeys view a 1 + 1 operation, they expect exactly 2 objects. It is likely that these numerical representations are spontaneously available to a variety of primate species and could provide a foundation on which humans' number sense was constructed over evolution and development.     

Being Close and Being Social: Peer Ratings of Distinct Aspects of Young Adult Social Competence

Adaptation to contact lenses was chosen as a paradigm for a process of adjustment to self-selected stress. It was hypothesized that a tendency to cope actively with novel and complex situations is needed for success in adapting to this type of situation. Forty women, ages 16 to 33, before receiving contact lenses for cosmetic reasons, were administered the Shanan Sentence Completion Test, the Petrie experiment and a questionnaire. Two months later, objective symptoms, subjective complaints and feelings about adaptation and results were assessed. A significant positive relationship was found between the tendency to cope actively and success (number of hours wearing time per day). General positive motivation for self-realization in relation to people and for constructive activity was highly correlated with success, whereas situation specific motivation was not. Ss who tended to decrease stimulation on the Petrie experiment were more successful than those who “augmented.” The relevance of these findings for a theory of coping behavior and its assessment was discussed.     

A Primate Dictionary? Decoding the Function and Meaning of Another Species' Vocalizations

Decoding the function and meaning of a foreign culture's sounds and gestures is a notoriously difficult problem. It is even more challenging when we think about the sounds and gestures of nonhuman animals. This essay provides a review of what is currently known about the informational content and function of primate vocalizations, emphasizing the problems underlying the construction of a primate “dictionary.” In contrast to the Oxford English Dictionary, this dictionary provides entries to emotional expressions as well as potentially referential expressions. It therefore represents a guide to what animals do with their vocalizations, as well as how they are represented by signalers and perceivers. I begin by a discussion of the unit problem, of how an acoustic space is carved up into functionally significant components leading to a species‐specific repertoire or lexicon of sorts. This section shows how little we know about the units of organization within animal vocal repertoires, and how such lack of information constrains our ability to tackle the problem of syntactic structure. In Section III, I review research on the production and perception of vocal signals that appear to be functionally referential. This work shows that several nonhuman primates produce vocalizations that share some of the key properties of reference, but certainly not all; the components that are missing raises questions about their role as precursors to human words. In Section IV, I explore the social uses of vocalizations, assessing whether the signal contains sufficient information for listeners to judge a caller's credibility; ultimately, caller credibility determines how receivers select an appropriate response. Results show that individuals can use calls to assess whether someone is reliable or unreliable, and that such attributes are associated with individuals and particular contexts. I conclude by synthesizing the issues presented and then raise some directions for future conceptual and methodological progress.