Displacement activities occur when an animal experiences high motivation for two or more conflicting behaviours: the resulting displacement activity is usually unrelated to the competing motivations. 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 may also occur when animals are prevented from performing a single behaviour for which they are highly motivated. Displacement activities often involve actions which bring comfort to the animal such as scratching, preening, drinking or feeding.

In the assessment of animal welfare, displacement activities are sometimes used as evidence that an animal is highly motivated to perform a behaviour that the environment prevents. One example is that when hungry hens are trained to eat from a particular food dispenser and then find the dispenser blocked, they often begin to pace and preen themselves vigorously. These actions have been interpreted as displacement activities, and similar pacing and preening can be used as evidence of frustration in other situations.

Psychiatrist and primatologist Alfonso Troisi proposed that displacement activities can be used as non-invasive measures of stress in primates. He noted that various non-human primates perform self-directed activities such as grooming and scratching in situations likely to involve anxiety and uncertainty, and that these behaviours are increased by anxiogenic (anxiety-producing) drugs and reduced by anxiolytic (anxiety-reducing) drugs. 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".

More recently the term 'displacement activity' has been widely adopted to describe a form of procrastination. It is commonly used in the context of what someone does intentionally to keep themselves busy whilst, at the same time, avoiding doing something else that would be a better use of their time.