AR-News: Breakthrough: Chimpanzees remember things too

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From: primfocus at waste.org
Anim Cogn. 2004 Apr;7(2):86-92. Epub 2003 Sep 18.


Long-term retention of the differential values of Arabic numerals by
chimpanzees ( Pan troglodytes).

Beran MJ.

Language Research Center, Georgia State University, 3401 Panthersville Road,
GA 30034, Decatur, USA, mjberan at yahoo.com

As previously reported (Beran and Rumbaugh, 2001), two chimpanzees used a
joystick to collect dots, one-at-a-time, on a computer monitor, and then
ended a trial when the number of dots collected was equal to the Arabic
numeral presented for the trial. Here, the chimpanzees were presented with
the task again after an interval of 6 months and then again after an
additional interval of 3.25 years. During each interval, the chimpanzees
were not presented with the task, and this allowed an assessment of the
extent to which both animals retained the values of each Arabic numeral.
Despite lower performance at each retention interval compared to the
original study, both chimpanzees performed above chance levels in collecting
a quantity of dots equal to the target numeral, one chimpanzee for the
numerals 1-7, and the second chimpanzee for the numerals 1-6. For the
3.25-year retention, errors were more dispersed around each target numeral
than in the original study, but the chimpanzees' performances again appeared
to be based on a continuous representation of magnitude rather than a
discrete representation of number. These data provide an experimental
demonstration of long-term retention of the differential values of Arabic
numerals by chimpanzees.




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