Extralimital triradii as a putative marker of schizotypy.

Dermatoglyphic anomalies are reported to occur at a higher rate in schizophrenic patients and schizotypic individuals than in the general population, supporting the hypothesis that they are a marker of vulnerability for such conditions. Dermatoglyphic anomalies are hypothesized to indicate severe disruptions in the second trimester of prenatal development, a time period that appears to be etiologically relevant to the development of schizophrenia and related conditions. The present study provides the first examination of extralimital triradii in schizotypic young adults (n=197) and control participants (n=135) identified by the Revised Social Anhedonia Scale [Eckblad, M., Chapman, L.J., Chapman, J.P., Mishlove, M., 1982. The Revised Social Anhedonia Scale. Unpublished test (copies available from T.R. Kwapil, Department of Psychology, University of North Carolina at Greensboro P.O. Box 26164 Greensboro, NC 27402-6164)], the Perceptual Aberration Scale [Chapman, L.J., Chapman, J.P., Raulin, M.L., 1978. Body image aberration in schizophrenia. J. Abnorm. Psychol. 87, 399--407], the Magical Ideation Scale [Eckblad, M.L., Chapman, L.J., 1983. Magical ideation as an indicator of schizotypy. J. Consult. Clin. Psychol. 51, 215--225], and the Physical Anhedonia Scale [Chapman, L.J., Chapman, J.P., Raulin, M.L., 1976. Scales for physical and social anhedonia. J. Abnorm. Psychol. 85, 374--382]. As hypothesized, the schizotypic participants (6.6%) exhibited significantly higher rates of extralimital triradii than control participants (1.5%). These findings strongly encourage the future investigation of extralimital triradii in at-risk and psychotic populations.