Psychological Medicine, 1980,10, 133-138 Printed in Great Britain Auditory sensitivity in psychiatric patients and non-patients: monotic click detection GERARD BRUDER, 1 BONNIE SPRING, 2 ALLAN YOZAWITZ 3 AND SAMUEL SUTTON From the Department of Psychophysiology, New York State Psychiatric Institute, New York, USA SYNOPSIS The sensitivity in detecting a click was measured separately for the right and left ear of psychiatric patients and non-patient controls using a three-interval forced-choice staircase procedure. Patients with affective disorders showed reduced right ear sensitivity, while schizophrenic patients did not show reduced sensitivity. Lower sensitivity correlated with higher structured- interview ratings of speech retardation. INTRODUCTION The study of sensory processing in psychiatric patients has been greatly advanced by 2 methodo- logical developments in the field of sensory psychology. First, signal detection methods (for example, three-interval forced-choice procedures) allow the measurement of the sensory sensitivity of patients independently of confounding effects of non-sensory judgemental or decision variables (Clark et al. 1967; Emmerich & Levine, 1970; Bruder et al. 1975; Malone & Hemsley, 1977). Secondly, efficient 'up-down' staircase tech- niques (Wetherill & Levitt, 1965; Taylor & Creelman, 1967; Campbell & Lasky, 1968; Levitt, 1971) are available which minimize the time needed to measure the sensitivity of patients. In a previous study (Bruder et al. 1975) we took advantage of these 2 developments to measure the sensitivity of psychiatric patients for detecting a transient auditory stimulus (a click) in the right ear. Affective psychotic patients showed lower sensitivity when compared with schizophrenic patients and non-patient controls, while schizophrenic patients did not differ from non-patient controls in their sensi- 1 Address for correspondence: Dr Gerard Bruder, De- partment of Psychophysiology, New York State Psychiatric Institute, 722 West 168 Street, New York, NY 10032, USA. 8 Present address: Department of Psychology and Social Relations, Harvard University, William James Hall, 33 Kirkland Street, Cambridge, MA 02138, USA. ' Present address: Neuropsychology Laboratory, Hut- chings Psychiatric Center, 625 Madison Street, Syracuse, NY 13210, USA. tivity. The affective psychotic patients needed an additional 6 dB on the average to attain the same level of signal detectability as non-patients. The purpose of this report is to present auditory sensitivity data for new samples of patients and non-patients, whose sensitivity was measured separately for the right and left ear. METHOD Subjects All patients were tested within 2 weeks of admission to Kingsboro Psychiatric Center, Brooklyn, New York. Project staff reviewed the case file of each newly admitted male patient in the appropriate age range and held conferences with hospital staff about the patient. If the patient appeared to be suitable for the study, a screening interview was administered on the hospital ward. Only patients who communicated clear-cut affective or schizophrenic symptoma- tology were selected for testing. Non-patient controls were recruited from the New York State Employment Service and were screened to exclude those with a history of psychiatric hos- pitalization. Patients and non-patients were also excluded if there was evidence of drug or alcohol addiction, brain damage, epilepsy or mental retardation. This report presents the auditory sensitivity data for a total of 75 subjects from 2 separate studies which were being carried out at the same time, a dichotic listening study (Yozawitz et al. 133 O033-2917/80/2828-477O $01.00 © 1980 Cambridge University Press