Displacement activity

Birds, for example, may peck at grass when uncertain whether to attack or flee from an opponent; similarly, a human may scratch their head when they do not know which of two options to choose.

Displacement activities often involve actions which bring comfort to the animal such as scratching, preening, drinking or feeding.

[1] Psychiatrist and primatologist Alfonso Troisi proposed that displacement activities can be used as non-invasive measures of stress in primates.

In humans, he noted that similar self-directed behaviour, together with aimless manipulation of objects (chewing pens, twisting rings), can be used as indicators of "stressful stimuli and may reflect an emotional condition of negative affect".

These references to displacement activities in a work of literature indicate that the phenomenon was well recognized at the turn of the twentieth century.