Habituation

animal habituation(ethology)

1. HABITUATION

2. Habituation is the gradual reduction in response to a repeated stimulus that is irrelevant to the animal . If an animal is repeatedly given with a stimulus which is not associated with any reward or punishment it ceases to respond. The initial response to a new stimulus is usually one associated with danger. It can cause the organism to flee, crouch and become immobile or any other form of startle response.

3. As this stimulus which has no significant meaning to the animal is repeated it loses its novelty and the animal begins to ignore it. During habituation the animal can sense the stimuli but fail to respond to it. Habituation is a property of central nervous system and not of the sense organs. The benefit of habituation is that it eliminates the response to a frequently repeated stimulus that has no value in that particular context, saving time and energy.

4. EXAMPLES FOR HABITUATION When a land snail is placed on glass plate, after a few minutes it projects the stalked eyes and start crawling. If we knock on the plate, immediately it retracts the eyes and stops moving. After a pause for a few seconds , it moves again. A second tapping causes retraction, but the snail emerges quickly and moves on. If we continue tapping on the glass plate, the snail ignores and continues to move, inspite of the disturbance.

5. The chicks sees a shadow and drives into the nest thinking it is a raptor. Over time it learns to ignore some shadows because they are harmless.

6. The classic example of Habituation was shown by Tinbergen is of Hawk-goose model experiment in which when the silhouette was flown in hawk direction the young chicks of turkey were alert and tried to escape whereas when the silhouette move in goose direction the chicks didn’t react. This indicates that the turkey chicks were habituated with goose shadow since geese are very common in nature and they often fly over head. But the shadow of hawk was strange for the chick and hence they were frightened.

7. Prairie dogs retreat into their holes at the sound of approaching human footsteps. When this occurs many times and the prairie dogs know the footsteps are not a threat, they no longer retreat at the sound of footsteps. An abused cat is very wary human touch ,but once it realizes that its new owner pose no threat ,it becomes used to petting.

8. A caged hamster becomes frightened when a person taps on its cage; however, when it realizes that the taps pose it no danger, it becomes used to hearing them. Ducks in a small pond at a park are scared of people and fly away when approached. They become used to humans over time as they interact with them and as people feed them , causing them to realize that the humans are not a threat.

9. Sea anemones pull food into their mouths. If they are stimulated repeatedly with non-food items ( sticks,for example) they will then begin to ignore the stimulus.

10. Neries pelagica (marine clamworm)-lives in burrows, stretching out tentacles to trap food. If a shadow passes over-quickly withdraws into burrow. Repeated shadows –stops responding to it.

11. Certain noises in a house cause a newborn baby to cry, until he or she becomes desensitized to the noises and they no longer frighten the children. A turtle draws its head back into its shell when its shell is touched. After being touched repeatedly , the turtle realizes it’s not in danger and no longer hides.

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