Schizophrenic sign language : mirror or window?

Thirty five preverbally deaf adults, thirty of whom have clinical diagnosis of schizophrenia, and five who have been diagnosed manic-depressive, were interviewed in British Sign Language (BSL). Diagnoses in 23 members of this group were confirmed by our BSL/deaf culture translation of the Present State Examination (Wing, Cooper and Sartorius, 1974)and Thacker (1994). Their performances were compared to a group of healthy deaf adults matched for sex, age, ethnic background, handedness, non verbal IQ and age of sign acquisition. The interview contained both closed (e.g. picture description)and open-ended questions similar to those found in psychiatrics interviews.

The hypothesis was that a formal thought or language disorder would manifest itself in signed as well as spoken language. Analysis of the videotaped interviews does indeed reveal behaviours comparable to those seen in hearing schizophrenics, as well as phenomena only possible on a visual-spatial medium.

Errors include : neologisms, reversal of the movements of signs, "clangs" (sign choice based on manual feature rather than meaning), perseveration of signs and topics, stereotypies, echopraxia, poverty of sign and of content, cross-linguistic (spoken/signed)contamination, derailment and failure of discourse devices in addition to visual-spatial phenomena. An example of the latter is the schizophrenic subject who assigned different personalities to her two hands. Syntax errors occur more often in the control group than in the patient group.