Abstract # 222:

Scheduled for Saturday, August 19, 2006 11:00 AM-11:15 AM: Session 21 (Regency East #3) Oral Presentation


DISSECTING THE ACOUSTIC UMBILICAL CORD: SELECTIVE MATERNAL RESPONSIVENESS TO PARTICULAR ACOUSTIC FEATURES OF RHESUS MACAQUE (Macaca mulatta) INFANT GECKER VOCALIZATIONS

E. R. Patel1 and M. J. Owren2
1Cornell University, Department of Psychology, Behavioral and Evolutionary Neuroscience Division, Ithaca, NY 14853, USA, 2Georgia State University, Department of Psychology and Language Research Center, Atlanta, GA 30302-5010
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     Infant "distress" or "separation-rejection" vocalizations are found throughout the primate order, including "gecker" calls in rhesus monkeys (Macaca mulatta). While such sounds are considered crucial for maintaining mother-infant proximity, mothers nonetheless often fail to respond to them. Using simultaneous audio-recording and behavioral coding, we examined the acoustics and maternal response to 111 bouts of gecker vocalizations emitted by 10 (6 males, 4 females) socially living rhesus infants at the California National Primate Research Center through the first 17 months of life. Mothers responded to only 38% of gecker bouts, and as in previous work, were most responsive to the youngest infants and males. Multivariate logistic regression identified two frequency variables, harmonic-to-noise ratio and the first well-defined high-amplitude spectral peak, that predicted maternal response (p < .02). Maternal response was most likely to gecker bouts with high spectral peaks and to a smaller degree, less noisy gecker bouts. Prediction accuracy was substantially higher for cases of no response (96%) than cases where mothers did respond (66%). In sum, mothers were surprisingly selective in responding to infant geckers according to the age, sex, and acoustic features of the calls. High spectral peaks may be aversive to mothers and thereby increase the likelihood of response. Supported by NIH grant RR00169 and NICHHD grant NS19826.