When the monkeys touched the pictures in ascending order, i.e., one square, two trees, three ovals and four flowers, they received a banana-flavored food pellet. If they made an error, the screen turned black for several seconds and a new trial began with different pictures. This 'video game' paradigm, which the monkeys now clearly enjoy, trained them to perform cognitive serial tasks without verbal instructions -- without language, the researchers said.
"It's like using your password to get money from a cash machine, but it's actually much harder for the monkeys," Prof. Terrace said. "The pictures, and their position on the screen, change each time they try for another pellet of food. When you go to a cash machine, you don't have to deal with the numbers being in strange positions each time. We ask a lot, cognitively speaking, of our non-human primate subjects."
Over the course of learning 35 different training sets, the monkeys got better and better at responding in the ascending numerical order, one to four. The two psychologists then tested Rosencrantz and Macduff on 150 test trials, in which a new stimulus set, showing numbers of objects from five to nine, was presented on each trial. The monkeys performed just as well as they had on the original 35 training sets.
"There was no way the monkeys could have done this, unless they had
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Contact: Bob Nelson, Office of Public Affairs
rjn2@columbia.edu
212-854-6580
Columbia University
23-Oct-1998