Perceptual and Motor Skillr, 1991, 73, 31-37. O Perceptual and Motor Skills 1991
SCHIZOPHRENIA AND AUTOMATIC PROCESSING: AN EXPLORATORY STUDY '
University of Vakncza, Spain Summary.-This study deals with the schizophrenic deficit as one of automatic processing. To test the idea, a special experimental task was designed on which 21 schizophrenics, 21 depressives, and 21 normal subjects had to complete a series of simple geometric figures. When the subjects had thoroughly learned this activity, another information source, a brief story, was introduced, and the subjects had to pay attention to the story while they did the task. Two dependent variables were considered, execution time and performance. There were no differences among the three groups in the First experimental condition; but in the second condition, when the distractor was introduced, schizophrenics needed more time to do the task and their performance was noticeably worse than those of both normals and depressives. This outcome is explained in terms of a failure in the internal mechanisms which regulate the automatic, parallel, and unconscious processing.
After years of research and theoretical discussion on the intriguing nature of schizophrenia, agreement seems to have been reached with respect to some general and common defining features. One of these features is that the most defined deficit is cognitive in nature. Cognition is usually divided into two kinds of processes (Anscombe, 1987; Kahneman, 1973; Posner, 1982; Schneider & Shiffrin, 1977; Shiffrin & Schneider, 1977). The first kind implies an automatic access to mental content and involves the basic organization of the perceptual input. This cognitive capacity allows individuals to proceed in parallel with two or more activities, without diminishing the performance of either. The second kind of cognition is slow, voluntary, controlled, and requires effort; the amount of information that can be processed at any given moment is limited. Such cognition is serial and involves temporary sequences of mental operations under the subject's control and activated by the attentional resources. Moreover, the changing assumptions from the early simple-box processing models (that were uniformly serial models) to approaches that reflect an interest in the nature of the inferred internal mechanisms-representations and processes-were accompanied by a new view of attention, that is, attention not yet conceived as an initial process but, as a directional activity parallel to the other cognitive activities, makes use of the processing capacity to allow cognitive functioning. As Johnston and Heinz (1978) have shown, attention needs processing capacity, and the cognitive performance depends on effort or capacity (Kahneman, 1973). 'Address correspondence to Prof. A. Belloch, Dept. de Personalidad, Facultad de Psicologia, Avda. Blasco Ibiiiez, 21, 46010-Valencia, Espaiia.
A. BELLOCH, ET AL
From this last view, we can suggest at least two basic assumptions about the consequences of an attentional dysfunction involved in the pathogenesis of schizophrenia: firstly, this dysfunction or pattern of dysfunctions may never be specific; on the contrary, dysfunction will be evident on a wide range of cognitive tasks and in various situations. Secondly, the dysfunction becomes more evident as greater effort and/or processing capacity is required. We think both assumptions are in accord with the views of schizophrenic attentional deficits as reflecting lower processing capacity rather than a structural breakdown at a specific stage in the information-processing chain (Gjerde, 1983; Nuechterlein & Dawson, 1984). In the present study, we focussed primarily on the second assumption, that is, those related with the interface between dysfunction and effort-processing capacity. With this purpose, we have constructed a special experimental task, which, at this stage, has only an exploratory aim with respect to the assumption that pardel processing might occur whenever the combined processing capacity for several tasks is less than a person's total attentional supply. METHOD Subjects The over-all sample was composed of 63 male subjects, divided into three groups: 21 schizophrenics, 21 depressives, and 21 normal subjects. All the groups were from similar geographical origin (small towns close to the city), with similar jobs (farmers, bricklayers, and unskilled workmen), and with similar education (primary education). There were no statistical hfferences in age which ranged from 20 to 34 years (M and SD = 28.4 and 3.3 yr., respectively). The schizophrenic group were inpatients at the Psychiatric Hospital in Valencia and were selected on the basis of the DSM-111-R criteria for Schizophrenia, subchronic course. From them, 11 patients were diagnosed as undifferentiated subtype, 6 as disorganized subtype, and 3 as paranoid type. All patients were tested during the first week after admission to the hospital and for this reason all of them were in an acute stage of schizophrenic disorder. Medication could not be controlled, and aII patients were on some form of phenothiazine medication at typical antipsychotic doses. No patients were receiving ECT or had a history of brain damage or a documented history of alcohol or drug abuse. Due to the subchronic course diagnosis, all patients had prior histories for schizophrenia, ranging from six months to two years. The depressed group were outpatients who were in regular touch with the Outpatient Service at the Psychiatric Clinic of the General Hospital in Valencia. Diagnostic decisions were also made on the basis of DSM-111-R criteria (Dysthymia), and no psychotic features had been observed in these patients. All were on antidepressants or minor tranquilizers at the time of the study.
SCHIZOPHRENIA AND AUTOMATIC PROCESSING
The normal control group were individuals with no psychiatric antecedents. They were selected after the schizophrenic and depressive groups had been formed. AU of them were recruited from the Outpatient Services at both the Chest and Cardiovascular Clinics of the General Hospital in Valencia. Measures
All the subjects were individually tested. First of all they completed a Memory Test (Yuste, 1982). Secondly, they ~erformedan experimental task and then completed a second task of verbal free-recall. The description and the reasons for the use of these tasks are as follows: (a) Yuste's Memory Test.-This test is composed of three difficulty levels, based on age. We selected Level I11 employed with subjects older than 15 years. On this test a brief story is read aloud; then the subjects have to write it out or tell it. Changes or omissions are not penalized and a literal reproduction is not intended, but a reliable content is looked for. The highest score includes 30 items (nouns, verbs, etc.; M and SD = 20.61 and 6.33). We used this test to exclude subjects with memory deficits and to have a recall index as a criterion for inferring the distractor's influence on the experimental task. (b) Experimental task (sustained and parallel attention task) (Baiios, 1987).-Subjects had to complete a repeated series of geometric figures (squares, circles, and equilateral triangles) as quickly as possible, having in view a model located at the top of each page. The subject was asked to draw the underside of both squares and triangles and the right half of the circles to complete the figures. Subjects were informed that once they had learned to do the task, a brief story would be read aloud, and they should continue to do the task. The accurate performance (i.e., without mistakes or omissions) of one page containing 7 lines and 3.5 figures was considered as a trial, so the experimental task began when the subject understood the instructions completely and performed a one-trial page. Then subjects completed two pages of figures. The first execution time was then taken (preautomation time). Afterwards, the story was read and finished when the subject had completed two other pages; then the second execution time was taken (postautomation time). Finally, the subject was asked to recall the story. Here, the specific objective was to study to what extent the introduction of a memory task has a distracting effect or interferes with the performance of an overlearned and automated visuomotor task that requires minimal attentional effort. This task is based on the assumption proposed by several authors (e.g., Underwood, 1976) on processing capacity. In this way, it has been argued that practicing a task reduces the processing capacity required and thereby increases the attention that can be devoted to something else. From this line of reasoning the Continuous Performance Test, proposed
A. BELLOCH, ET AL.
by Rosvold, Mirsky, Sarason, Bransome, and Beck (1956), or the task proposed by Kay and Singh (1974) can also be so conceived. Yuste's Memory Test The schizophrenic group showed the lowest score (M = 18.2 and SD = 7.7), followed by the depressed group (M and SD = 20.3 and 4.3), and then the normal group who obtained the highest score (22.1 and 4.2). There were no significant differences amongst groups (F,,,, = 1.65), so we can suppose that possible problems in the recall story on the experimental task are not influenced by memory deficits. Experimental Task Two dependent variables were considered, execution time (in seconds) and performance quality (number of mistakes), both for the pretest condition (without distractor) and the posttest condition (with distractor). We obtained four measures for each of the subjects, i.e., pre- versus postexecution time and pte- versus postperformance. In Table 1 are the means and SD values for each one of these measures. TABLE 1
MEANS AND STANDARDDEVIATIONS ON DEPENDENT VARIABLESFORTHREE GROUPS Group
M Schizophrenics Depressives Normals
21 21 21
.5 .3 .4
.2 .2 .8
124.0 118.0 97.7
47.4 68.5 18.6
3.1 .05 .2
197.0 116.0 69.5
89.4 69.0 27.1
As Table 1 shows, very few mistakes were made on pretest by all three groups of subjects. An analysis of variance showed no significant group effect for performance without distraction (F,,, = 2 2 ) . For the execution times at pretest (see Table I), the analysis of variance indicates no significant group effect (F,,, = 1.72). Taking into account these results at pretest, we can reasonably assume that the task was easy, required little effort or capacity, and so should probably be conceived as an indirect automation index for all three groups. At posttest, when the distractor was introduced and the subjects distributed their attentiond resources, i.e., paid attention to a new information source while continuing to perform the overlearned task, the results were as follows. Firstly, an analysis of variance for posttest performance showed a significant effect for group (F,,,, = 12.3, p < .0001). Post hoc comparisons of separate groups by Tukey test indicated that schizophrenics performed significantly more poorly on the experimental task than the normal (F,,,, =
SCHIZOPHRENIA AND AUTOMATIC PROCESSING
4.86, p < .01) and depressed groups (F,,,, = 10.0, p < .OOOl). There were no differences between normals and depressed outpatients (F,,4,= .lo). Secondly, an analysis of variance for posttest execution times indicated a significant effect for group (F,,60 = 19.40, p