Described a five-step procedure that can be used to detect organicity on the basis of children's performance on the Minnesota Percept0 Diagnostic Test (MPD). The first step consists of examining the T score for rotations to determine whether it is below the cut-off score, which has been established empirically as an indicator of organicity. The second step consists of matching the examinee's configuration of error scores, separation of circlediamond (SpCD), distortion of circle-diamond (DCD), and distortion of dots (DD), with empirically derived tables. The third step consists of considering the T score for rotations and error configuration jointly. The fourth step consists of using empirically established discriminant equations, and the fifth step involves using data from limits testing and other data sources. The clinical and empirical bases for the five-step procedure also are discussed.
The Minnesota Percepto-Diagnostic Test (MPD) (Fuller, 1969(Fuller, , 1982;;Fuller & Laird, 1963) provides useful information for differential diagnosis of brain damage. The MPD is a clinical test that measures the degree of disruption in visual-motor perception. When scores are considered in conjunction with relevant theoretical formulations (e.g., Fuller, 1982;Rabinovitch, 1959) and other assessment data, the MPD can make a substantial contribution to differential diagnosis between brain damage, emotional disturbance, and reading disabilities. The MPD then provides a highly sensitive measure of the degree of disruption in visual-motor perception. However, the information that it provides must be interpreted in light of research and theoretical formulations about the extent to which perceptual processes are disrupted in different clinical groups. The present paper provides a description of how the MPD was developed, a review of relevant research and theory, and an explanation of how this information can be combined into a five-step clinical procedure for using the MPD in the differential diagnosis of brain damage. The five-step procedure is illustrated through the use of case material from neuropsychological assessments.
Development
The MPD consists of six cards, which contain two Gestalt designs with their frames in varying positions. The starting point for the development of the MPD was the five Wertheimer designs most susceptible to rotation, separation, and distortion. The work of McPherson and Pepin (1955), Goldberg (1957), and Freed (1966) indicated the relative instability of these designs. An early study by Fuller and Chagnon (1962) involved administration of the five least stable designs to normal, emotionally disturbed, and schizophrenic children. These five designs were organized into six sets by varying the orientation of the designs and their frames. This made a total of 30 different cards, which were administered to all children in the three groups. The work of Shapiro (1953) and Williams, Lubin, Gieseking, andRubinstein (1956) suggested that a diamond-shaped ground and a vertical figure might be expected to maximize the perceptual conflict, and 'Reprint requests should be sent to Gerald B. Fuller,