Information processing stages in schizophrenia

Abstract

General background FROM Kraepelin on, and perhaps before, investigators have been intrigued by the slowness of schizophrenics as one reflection of their disorder. The modern history can be said to begin with the Worcester group,l,z starting with the work of SHAKOW and HUSTON3 and extending to the current scene.4*5 Ignoring minor exceptions, it is a universal finding that schizophrenics are slower than controls, with the smallest differences appearing in simple reaction time (RT) at very short preparatory intervals. The details of the relevant experiments have been reviewed extensively.6-8 Most germane to our current concerns are the hypotheses offered to account for the results. In general, they concentrate on input dysfunctions. Thus, SHAKOWg proposed that retardation of RT resulted from the inability of the schizophrenic to maintain the major set required by the situation, with the concomitant arousal of erratic minor sets. WISHNER~~ has argued that the “segmental set” theory is a special case of inefficiency in schizophrenic behavior, which is generally diffuse in relation to task requirements. MCGHIE” emphasized attentional dysfunction localized at the filtering mechanism postulated by BROADBENT.‘~,~~ At the physiological level, VENABLES 14.15 adduced evidence to support a theory of extreme levels of arousal as accounting for the variability of schizophrenic performance. None of these theories are sufficiently precise to generate critical experiments. It is not surprising, therefore, that the overall results of the research undertaken to test them are inconclusive.7 The most detailed attempt to deal with attentional dysfunction in schizophrenia has been that of YATES.16 He proposed that there are four “levels” at which dysfunction can occur in schizophrenic information processing: receptor, data processing, cognitive, and motor. These look very similar to the stages proposed by Sternberg. Indeed, there is reason to view Yates’ idea as a first approximation to the more refined and operationally precise paradigm of Sternberg. Yates’ theory has been criticized precisely for failing to prescribe experiments which could lead to clear-cut conclusions ,17 for whatever dysfunctions are found at any of his “levels” could originate at any other level. No paradigm is provided for identifying loci of dysfunction. Sternberg’s paradigm, as will be seen below, is not subject to such criticism.