September 21, 2013 5:10 AM Subscribe
A study [PDF]
by CUNY Professor Diana Reiss
and Rachel Morrison (Biopsychology and Behavioral Neuroscience Subprogram in Psychology The Graduate Center of CUNY) was published last week in Zoo Biology
detailing for the first time a whisper‐like behavior in a non‐human primate, the cotton top tamarin
at the Central Park Zoo.
When exposed to a supervisor who had previously elicited a mobbing response, rather than exhibiting that and producing loud human‐ directed mobbing calls, the tamarins exhibited other anti‐predator behaviors and produced low amplitude vocalizations that initially eluded the scientists' detection. A post‐hoc analysis of the data was conducted to test a new hypothesis—the tamarins were reducing the amplitude of their vocalizations in the context of exposure to a potential threat. Consistent with whisper‐like behavior, the amplitude of the tamarins’ vocalizations was significantly reduced only in the presence of the supervisor.