New Paper by

I. H. Iversen & T. Matsuzawa

On Development of interception of moving targets by chimpanzees
was recently published in Animal Cognition, Springer-Verlag, INC.

Check online link to abstract and journal

Download the PDF version of the complete article!
The original publication is available at http://link.springer.de or at http://link.springer-ny.com

Full citation:
Iversen I. H., & Matsuzawa, T. (2003). Development of interception of moving targets by chimpanzees (Pan troglodytes) in an automated task. Animal Cognition, 6, 169-183.
 

The experiment demonstrated complex interception performance on a touchmonitor.

Subject Sitting in front of the Monitor

(supplemental electronic material S1 in the publication, copyright by Springer Verlag, Inc.)

Each trial the subject has to move the blue ball to the target (white quare). When the subject begins to move the ball the target moves predictably at a constant speed clockwise around the monitor edge. The target only moves when the ball is moved. The target and ball appear at different locations at trial start. Reinforcement, a piece of fruit is presented when the target it hit. Two adult, female chimpances, Ai and Pendesa acquired this task. They demonstrated highly accurate interception. The ball movement anticipated the target's movement such that the subjects moved the ball to a location where the target would arrive. The experiment illustrates the development of complex skills in a laboratory setting that simulate foraging skills seen in natural environments.

See video clip of a single trial of this performance
(supplemental electronic material S2 in the publication, copyright by Springer Verlag, Inc.)

In test conditions, the target unpredictably remained stationary. The purpose of the test was to see if the subjects would still move the ball so as to try to intercept the target as it would normally move. Both chimpanzees in fact moved the ball to where they would ormally move it and then turned and moved to where the target rested.

See video clip of a single trial of the performance during test with stationary target. .
(supplemental electronic material S3 in the publication, copyright by Springer Verlag, Inc.)

When the movement direction of the target was changed to counterclockwise -exactly opposite to the earlier training - the subject adjusted very quickly and within just 4 sessions intercepted the taget very effeciently.

See video clip of a single trial of the performance with counterclockwise target movement.
(supplemental electronic material S4 in the publication, copyright by Springer Verlag, Inc.)

During the first and second session of adjustment to the new direction of counterclockwise target movement, the subject developed an interesting looping performance that enabled the target to move toward the hand without the hand moving very much. This performance was replaced with the more efficient linear interception strategy.

See video clip of a single trial of this early adjustment performance when the target moved counterclockwise around the monitor edge.
.(supplemental electronic material S5 in the publication, copyright by Springer Verlag, Inc.)
 

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