Utilization behavior was investigated in an adult with an acute behavioral disturbance, memory deficits, and a localized inferior medial bifrontal lesion at the Psychology Department, National Hospital, Queen Square, London; the MRC Applied Psychology Unit, Cambridge; and Department of Neurology, Atkinson Morley's Hospital, Wimbledon; and St. Andrews Hospital, Northampton, UK. Incidental utilization behavior was observed and categorized: 1) Toying, an object manipulated but not in a purposeful way (e.g. picking up a pencil but not using it for any purpose), 2) complex toying, two objects used in a linked way but in an incomplete fashion (e.g. picking up a pencil and using it to move objects), 3) coherent activity, set of actions integrated in a typical fashion (e.g. picking up a pen and paper and writing; picking up a pack of cards and dealing). Utilization behavior occurred when the patient was in conversation with the examiner and also when performing both verbal and nonverbal neuropsychological tests. His WAIS Verbal IQ was 73 and Performance IQ 79. Performance on spatial, perceptual, language, and simple praxic tests was satisfactory in contrast to tasks involving a frontal or long term memory component which were uniformly and severely impaired. The utilization behavior was present in the absence of confusion or dementia. The utilization behavior occurred most frequently in the brief intervals between tasks, and more often when auditory verbal rather than visual motor tasks were being performed. A differentiation was made between two forms of utilization behavior: 1) an incidental form, as exhibited by the patient; and 2) an induced form, occurring with Lhermitte's procedure where the examiner stimulates the palm and fingers of the patient's hands with the object. [1]