Forced person-following: a new type of stimulus-bound behavior.

We report a new type of stimulus-bound behavior, denoted forced person-following, which we documented for a patient with hypoxic encephalopathy following a suicide attempt with carbon monoxide poisoning. The patient's brain was damaged in the bilateral frontal, parietal, and temporal lobes and in the basal ganglia. The patient was compelled to follow any person who came into his sight and would continue to do so until the person went out of his sight. The patient also exhibited certain primitive reflexes. The forced person-following exhibited by our patient appears to be a consequence of stimulus-bound behavior due to frontal lobe dysfunction and, to a lesser degree, severe cognitive dysfunctions, e.g., visuospatial deficits, which are related to damage in posterior cortices. The unique behavior exhibited by this patient might contribute to our understanding of innate human behavior.