Practice question · Multiple choice
A greylag goose whose egg is taken away mid-retrieval finishes the rolling sweep with nothing under her bill. Why would selection favour a behaviour that carries on after it has plainly become pointless?
Hints
- Weigh the cost of the occasional pointless sweep against the cost of the alternative design.
- What would the goose have to do, continuously, for the behaviour to be interruptible?
Show the answer
C. Because the sequence is released rather than steered.
Why
It looks like a bug and it is a reasonable trade: checking the target continuously needs sensing, comparison and the ability to abort, and eggs very rarely vanish mid-roll. The empty sweep is the price of a ballistic design, and the moment a behaviour runs into pointlessness it reveals it was never being guided by the goal.
Practise Fixed Action Patterns
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More questions on Fixed Action Patterns
- Sort each behavior by whether it is a Fixed Action Pattern or flexible, learned behavior.
- A gull chick pecks harder at a striped stick than at a realistic model of its parent's head. Tinbergen called…
- Select every statement that is TRUE about sign stimuli and supernormal stimuli.
- A goose that has begun the egg-rolling fixed action pattern will stop mid-movement if the egg is taken away.
- Order the causal chain of a Fixed Action Pattern, from trigger to completion.