Wednesday, June 17, 2009
Scientists at Harvard University have shown, for the first time,
that intelligence varies among individual monkeys within a species
– in this case, the cotton-top tamarin.
Testing for broad cognitive ability, the researchers identified
high, middle, and low performing monkeys, determined by a general
intelligence score. General intelligence, or "g," is a hallmark of
human cognition, often described as similar to IQ. The effect of
"g" in primates may offer insight into the evolution of human
general intelligence.
The study, published this week in the journal PLoS One, is the
first to examine differences of broad cognitive ability in primates
within a single species. Previous studies of general intelligence
in primates primarily concerned variation between species.
The research was led by Konika Banerjee, a research assistant in
the Department of Psychology at Harvard University. Banerjee's
co-authors are Marc Hauser, professor of psychology, and James J.
Lee all of Harvard, along with Christopher Chabris of Union
College, Fritz Tsao of Hillsdale College, and Valen Johnson of the
University of Texas Medical School at Houston.
"We found that there was substantial individual variation in
performance on these tasks," says Banerjee. "A significant
proportion of that variation can actually be accounted for by
something that looks very similar to the general intelligence, or
'g' factor, in humans. It appears to be the case that tamarins have
something very similar to our general intelligence."
General intelligence, or "g," refers to the positive correlation of
an individual's performance on various subtasks within an
intelligence test. Banerjee and her colleagues found that "g"
accounted for 20 percent of the monkeys' performance on the tasks
in the study. The remaining 80 percent of the variation in
performance was due to task-specific or environmental circumstances
in testing the monkeys.
While not a direct comparison, human "g" accounts for 40 to 60
percent of the variation in an individual's performance on the
various subtasks of an IQ test. It may be that an increase in the
magnitude of "g" was integral to the evolution of the human
brain.
"General intelligence is an important component of human
intelligence, but it is also possible that it relies upon ancient
neural substrates," says Banerjee. "If different primate taxa
differ in the magnitude of 'g,' with humans standing out from the
rest of the pack, this might help explain how we, uniquely, can
combine thoughts from different domains of knowledge to create new
representations of the world. This cognitive domain general
ability, captured by 'g,' is something that you might see to
varying degrees in other primate taxa."
This study was conducted among 22 cotton-top tamarins, who were
administered 11 unique tasks designed to assess different cognitive
functions including working memory, executive control, information
processing speed, and inhibitory control. For some tasks, the
monkeys' goal was to obtain a piece of food, but this was not the
case for all of the tasks. Monkeys with higher "g" scores tended to
outperform monkeys with lower scores across the various subtasks in
the cognitive task battery.
This particular set of tasks was developed for this study, but
Banerjee hopes that it or other similar task batteries might be
applied to future studies of primate general intelligence, to
develop a standardized test for cognitive ability that could be
administered to many species.
"We called our cognitive task battery the 'monkey IQ test' very
crudely," says Banerjee. "It's a fun way to think about it, but to
be more accurate, I would say that we are looking at global
cognitive ability across an array of tasks that span multiple
cognitive domains."
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Harvard University
Thanks to Harvard University for this article.
