Behavioural despair test

The time that the test animal spends in the second trial without making any movements beyond those required to keep its head above water[3] is measured.

[6] Classically, immobility in the second test has been interpreted as a behavioural correlate of negative mood, representing a kind of hopelessness in the animal.

Rodents given antidepressants swim harder and longer than controls (which forms the basis for claims of the test's validity).

[7] However, there is some debate between scientists whether increased immobility instead demonstrates learning or habituation, and would therefore be a positive behavioural adaptation:[8] the animal is less fearful because it is now familiar with the environment of the test.

This interpretation is supported by the fact that even rats who are first put into a container from which they can escape (and therefore do not experience despair) show reduced mobility in the second test.