Introduction The simulation or exaggeration of behavioral inefficiency referable to presumptive brain injury is a persistent problem in clinical practice. Subjective complaints of excessive fatigability, impairment in memory, difficulty in concentration, and disturbances in work-capacity are always somewhat difficult to evaluate. They are particularly so when questions of compensation for injuries received or a pension are involved in the case. When an individual who is simulating mental incompetence or exaggerating the severity of his behavioral disability following some incident whichmayhave produced brain injury is given a battery of psychological tests, it is reasonable to suppose that his performance will be on a lower level than that which he is actually capable of and that he will attempt to perform in a manner which he believes to be characteristic of a brain-damaged patient. One question which arises in this respect is how successful