Psychologica l Bul le t in SOURCES OF REPORTS OF VISUAL AND AUDITORY SENSATIONS IN PERCEPTUAL - ISOLATION EXPERIMENTS

The review analyzes the experiments on perceptual isolation with special reference to the phenomena of reported visual and auditory sensations. Variables analyzed include: methods of confinement and restriction, conditions of illumination, duration of isolation, set, instructions and suggestions , reporting or verbalization instructions, sleep, subject populations, prior knowledge and expectations, intelligence and personality characteristics of Ss, stress response, and methods of obtaining reported visual and auditory sensations. The relevance of some of the findings to physiological , psychoanalytic, cognitive, and social psychological theories of perceptual isolation are discussed. Variables which seem important in the phenomena discussed are set, verbalization instructions, S's alertness, and E's methods of obtaining responses. The unexpected reports of hallucinations in the first perceptual-isolation report (Heron, Bexton, & Hebb, 19S3) fascinated clinicians, theoreticians, and experimentalists, and stimulated widespread interest in other responses to isolation. 1961), it is apparent that a decade after the original study the sources of variation in reports of hallucinatory-like The authors wish to acknowledge the generous cooperation of the investigators who, in many cases, had to spend considerable time reexamining their raw data. phenomena are still unknown. The reasons are the lack of comparability of conditions, subjects (Ss), and procedures used by the different experi-menters (Es), as well as the lack of agreed-upon criteria for the response variables. The purpose of this paper will be to relate the situational, subject, and response variables in studies to the reported incidences of visual and auditory sensations. Reported auditory sensations will be less thoroughly analyzed because of the lack of data on this in many studies and for reasons which will be discussed later. The variation in terminology in this area is symptomatic of the disagreement about the crucial variables in the complex experimental situation. The situation has been called "sensory deprivation ," "decreased sensory variation," "sensory isolation," "sensory alteration," "reduced sensory input," "physical iso