Fixed Action Pattern

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What It's About

This is a demonstratoin of how behavior that looks like a "fixed action pattern" or "programmed output" can be produced by a control system. It is a simulation of the behavior of a grey lag goose rolling its egg back into its nest. The behavior is seen in a video showing the ehtologist Conrad Lorenz snatching the egg away from the goose as it is being rolled back into the nest. The goose continues to make the movements that would roll the egg back into the nest even though the egg is no longer there.

The simulation shows that the same continuation of movement will occur if the variable controlled by a control system suddenly disappears as the egg does. In this tracking study, the connection of the mouse to the cursor (corresponding to the conection between egg and pressure on the back of the goose's bill) suddenly disappears, like the egg. The graph of the data shows the mouse movements of both a subject(you) and a control model shortly before and after removal of this conection. The results show that both you and the control model continue making the movements that would have kept the cursor on target for some time after the connection disappears, just as the goose keeps making the movements that would keep the egg pressing against the back of the bill even though the egg is no longer there.

For more information about this demo see Marken, R. S. (2002) Looking at Behavior through Control Theory Glasses, Review of General Psychology, 6, 260270

What to Do

Note: It is best to try this demonstration after you have learned to do the tracking task in the Nature of Control demonstration.

Last Modified: May 3, 2014