1. relating to a perception that is largely dependent on the qualities of the stimulation and thus involves little or no interpretation.

2. describing behavior that occurs in response to the presence of a specific stimulus (e.g., hungering for and eating a specific food after seeing it).

3. characterizing an individual whose behavior tends to be inflexible and determined primarily by the nature of the stimulus.

4. describing a person, usually a child, who has a poor attention span, is distracted by irrelevant stimuli, and therefore performs below his or her intellectual capacity.