a1 Department of Psychological Medicine, King's College Hospital, London
Repetition of other person's activities is, to some extent, part of normal human behaviour. However, in some circumstances it becomes pathological and symptomatic of an underlying disease process. The pathogenesis of this type of behaviour is very diverse. The circumstances in which echoing can be expected to occur are reviewed.
c1 Address for correspondence: Dr R. A. Ford, Department of Psychological Medicine, King's College Hospital, Denmark Hill, London SE5 9RS.