Starting a Career in Science: Challenges and Successes
Developing a Corporate R&D Career
Making Chemistry More Accessible
Envisioning Ancient Spaces, Virtually
KEEP US INFORMED:
Please send us your comments on this issue, ideas for future issues, and news about your professional interests and accomplishments.
Al Dorof, Editor
adorof@brynmawr.edu
info@brynmawr.edu
©2006
Imagine you are at a noisy restaurant where you are trying to have a conversation with your partner, who has asked you to explain your viewpoint about an issue that is important to both of you. You will unconsciously raise your voice over the din to make sure that your partner hears you. Scientists call this the Lombard effect, in which people unconsciously speak more loudly in noisy settings, and the degree to which they raise their voices depends on how important they believe the communication is to their listener. And, by the way, women raise their voices more than men in this type of setting.
 |
| Roain Egnor (second from right) with her Harvard undergraduate students (from left) Emily Baker, Jenny Taylor, Jeanette Wickelgren and Jasmine Dowell |
It so happens that we're not the only critters on the planet who demonstrate this effect, according to research conducted by S.E. Roian Egnor '90, a postdoctoral fellow in the Cognitive Evolution Laboratory (CEL) at Harvard University. Egnor is investigating auditory-feedback-mediated vocal modulation in cotton-top tamarins (Saguinus oedipus). She and Marc D. Hauser, a Harvard professor of psychology and director of CEL, will publish a paper in the American Journal of Primatology that refutes "the default view that nonhuman animal communication is reflexive — that animals would not vary the loudness of their calls in a noisy environment because they don't have an intended listener, nor do they evaluate whether the listener can hear them," Egnor explains. "In fact, not only do tamarins raise their voices in a noisy environment, they modulate the level of loudness depending on the social context."
Specifically, Egnor says, males raise their voices more in a social situation — when they are responding to their mates — than when they are spontaneously vocalizing. In contrast, females who are responding to their mates do not raise their voices as much as when they are spontaneously vocalizing. Egnor is interested in learning what information is being transmitted in vocalizations, how that information is encoded in the vocal signal, and how vocalizations change with time, behavioral context and auditory experience.
The cotton-top tamarin, a species of New World monkey, is a good species in which to address these questions, because these primates vocalize spontaneously and frequently in the lab and they have a large vocal repertoire — at least 38 distinct call types, Egnor says. In addition, their vocalizations are almost entirely tonal, which simplifies description, analysis and experimental manipulation. The colony of tamarins at CEL is composed of 12 social groups, consisting of mated pairs, some of which live with one or two generations of offspring.
Illuminating the Mind
An integrative neurobiologist, Egnor says she focuses on "the level of the circuit rather than the cell." She earned her doctoral degree at the California Institute of Technology, where she studied auditory processing and brain structures in the barn owl (Tyto alba). As a postdoctoral fellow at the University of California, Los Angeles, she studied the neural representations of acoustic and seismic stimuli in the leopard frog (Rana pipiens). Prior to her doctoral work at Caltech, Egnor worked in two Parisian AIDS clinics as a Watson Fellow, conducted research in Hawaii on endangered seals, and studied dolphin cognition at the Dolphin Research Center in Florida.
"I am very interested in how the brain works," Egnor explains. "Vocal communication is a measurable response that illuminates the mind of the person or animal that produced that vocalization. From the point of view of how animal minds work, it's a gold mine, because it tells us what kinds of things they are interested in saying to each other, what kind of complexity can be communicated from one animal to another, and how that information is transmitted."
Food, Sex and Predators
Egnor acknowledges that there is a good deal of overlap in the subject matter of human and nonhuman animal vocal communication. "We know the great common denominators are food, sex and predators, which are relevant for any living organism," she says. For example, she cites previous researchers' work with nonhuman primates demonstrating that there are specific, distinct vocal signals for terrestrial versus aerial predators: Vervet monkeys (Ceropithicus pygerythrus) understand the alarm call for "snake" because when they hear that alarm call, they stand up on their hind legs and look around in the grass, whereas, when they hear an alarm call for "eagle," they run under cover, as they should.
Yet, "no one has ever looked for evidence that nonhuman primates communicate something more subtle or more complicated, and that is what interests me," Egnor says. "I am interested in knowing what they are saying to one another."
At the conclusion of her Harvard fellowship, Egnor hopes to land a permanent academic position where she can establish a new colony of cotton-top tamarins to study over the course of their lives. She recalls a time when she was a Bryn Mawr student contemplating going to medical school. Her adviser, Eleanor A. Bliss Professor of Biology Paul Grobstein, convinced her that she had the mind of a scientist. "I'm really grateful for that," Egnor says. "This is an amazing, beautiful world, and finding out how it works is a privilege. It's exciting, fascinating and a joy."
Dorothy Wright contributes news and feature articles on science, technology, engineering and general-interest topics to a variety of publications, including Civil Engineering and Engineering News Record.