Br. J. SOC. din. Psychol. (r976), 15, pp. 275-286 Printed in Great Britain
Associative and Conceptual Organization in Thought Disorder BY B O Y D S . R I C H A R D S University of New Brunswick, Fredericton, Canada Thought disorder has frequently been described either as a disturbance of associative response hierarchies or as an inability to deal with objects or events as representative of classes. The tendency of normal subjects to organize free recall by clustering associatively or conceptually related words suggested the recall task as a means to investigate these views of thought disorder. Two groups of psychiatric patients, one with high scores on Lovibond’s version of the OST, one with low (thought-disordered and non-thought-disordered, respectively), were presented with randomly ordered word lists containing pairs related associtively and pairs related taxonomically. Thought-disordered and non-thought-disordered groups were not differentiated by any tendency to cluster more of one kind of pair than another. Rather, the thought-disordered showed a general lack of organization in recall, and significantly less improvement over trials in amount recalled. The results do not support the view that thought disorder is specifically a disorder of concept use or conceptual mediation. Research needs to be addressed to variables which affect the activation or inhibition of mediational links in thinking.
Two major research approaches to thought disorder have survived several decades. Stemming from Bleuler’s (1950) classic description of associative disturbance in schizophrenia are investigations of word association responses. Following Benjamin, Cameron, Goldstein, and others (Kasanin, 1944), there have been many studies of concept identification and abstraction, measured in such varied ways as object sorting, proverb interpretation and similarities tests. Bleuler’s description suggests that the associative disturbance underlies the conceptual, but research has generally treated them as separate phenomena, and modern studies continue to focus on an associative disorder or an abstraction disorder (e.g. Johnston, 1974; Watson, 1974). A concept is commonly defined by common response to dissimilar objects or events (Kendler, 1968;Osgood, 1953). In concept learning or identification, correct performance requires that each of the examples of the concept elicit the same response: a generic term in object sorting or similarities tests, for example. Willner (1965, 1966; Willner & Reitz, 1965, 1966) has shown that such tests are partly solvable by free association to the stimulus items, and what looks like conceptual responding may be ‘merely’ associative. T o the extent that the same responses are associated with each of the stimuli, concept identification is facilitated, and thus conceptual responding is mediated by associations. Attempts to describe ordered thinking rely on one or another mediation construct (Berlyne, 1965; Osgood, 1953; Voss, 1969), and verbal associative mediators have been given a prominent place in such theories. I t may be asked whether clinical thought disorder might represent a functional loss of mediational processes. In the simplest verbal mediation paradigm, Lang & Luoto (1962) demonstrated 275
18-2
276
BOYDS. RICHARDS
facilitation of paired-associate learning among chronic schizophrenics, suggesting no loss of mediation of the forward response-chaining type (AB, BC, AC). There is a lack of evidence concerning less direct mediation paradigms (Jenkins, 1963) in either schizophrenia or thought disorder. Conceptual mediation, or abstraction, refers to those cases in which two or more different stimuli evoke the same response (dog and cat are conceptually related by their common associative response, animal). Studies of mediation using natural language stimuli are complicated by the fact that words which elicit the same response often tend to elicit each other directly: cat is a more frequent response to dog than animal is to either. A measure of conceptual mediation which can control to a large extent the degree of direct associative relationships and also has particular advantages for use with psychiatric populations is that of organization in free recall of verbal items. The study of organization imposed by subjects in the free recall of verbal material has come to occupy a large part of the verbal learning field (cf. Tulving & Donaldson, 1972). Early on, studies involved the random-order presentation of items related in various ways, with measures taken of the tendency for related items to ‘cluster’, that is, to occur in immediate succession in recall. This organization in recall was studied as a function of conceptual or taxonomic class relations among items (Bousfield, 1953), and as a function of strength of normative association between words (Jenkins & Russell, 1952). Both types of experimenter-defined structure induced greater than chance clustering. A number of studies demonstrated that taxonomically related words were more likely to be clustered than nontaxonomically related words with strength of direct association controlled (Marshall 1963; Bousfield & Puff, 1965; Cofer, 1966). Taxonomic word pairs tend to have more word association responses in common than do non-taxonomic pairs of equal direct associative strength. Table and chair may each elicit the responses sit, kitchen, furniture, wooden, as well as eliciting each other directly. Bousfield has used this characteristic of taxonomic pairs to explain their greater clustering, and has pointed out that the property of eliciting common responses is that which defines a concept (Bousfield, Steward & Cowan, 1964; Bousfield & Puff, 1965). The recall of randomly presented word stimuli appears to involve mediation processes similar to those required by the more traditional abstraction tasks. The recall task may, in fact, be the more subtle test of mediational adequacy. Clustering is more a measure of typical performance than of achievement, since subjects are not instructed to organize their recall. The measure of clustering can be reasonably independent of amount recalled, so that task motivation is less of a confounding factor. T o date, the only extensive published studies of organiza‘ion in recall with clinical populations have dealt with mentally retarded children and adults (Herriot, Green & McConkey, 1973). Since the completion of the present study, Koh, Kayton & Berry (1973) have reported a comparison of young ‘nonpsychotic schizophrenics’, non-schizophrenic psychiatric patients and university students in recall and organization. They used in one instance a measure of organization which reflects the tendency for a subject to recall the same words in contiguity on successive trials. Their apparently remitted schizophrenics showed less of this inter-trial repetition than either of the other groups, if the original list
Associative and Conceptual Organization in Thought Disorder
277 contained taxonomic categories; group differences disappeared on uncategorized lists. On the other hand, when the amount of actual clustering of taxonomically related words was measured, the difference between the two patient groups disappeared, both being inferior to normals. These findings are interesting and relevant, but because of the mixed results and the bases for subject selection, it is difficult to see the implications for an understanding of either schizophrenia or thought disorder. Bannister (1968) has given clear reasons for studying thought disorder independently of schizophrenia, and recent studies underline the necessity for doing so (Andreasen & Powers, 1974; Depue, 1974). The present study was intended to explore the relations among recall, organizational processes and thought disorder. The general hypothesis was that thought disorder represents a functional loss of the mediating processes which order thinking, although the associative repertories of thought-disordered subjects are essentially normal. By presenting thought-disordered and non-thought-disordered subjects with word lists containing pairs varying in both associative strength and taxonomic relatedness it was possible to test more specific hypotheses. These were (I) that the thought-disordered would show less clustering in recall as well as less recall, and (2) that this group difference would be greater in the case of taxonomically related words. The latter result would be predicted by theories which specifically posit a loss of abstracting or conceptual ability in schizophrenic thought disorder; the failure of conceptual mediation should lead to lessened use of relationships based on indirect associative links, but does not imply a difficulty in using direct associative links. METHOD Materials Two lists of words were made up from lists published by Bousfield & Puff (1965) and used by them in earlier studies of normal subjects. One list (HA list) consisted of 12 pairs of words of high direct associative strength, the other (LA list) contained 12 pairs of relatively low associative connexion. Associative strengths were calculated by Bousfield & Puff on the basis of the Connecticut Free Associational Norms, using logarithmic measures of cultural frequencies with which each member of a pair elicits the other as response. Within each list, HA and LA, were six pairs which are taxonomically related in addition to being associatively related. For convenience, the two types of pairs will be referred to as taxonomic and associative pairs. The taxonomic pairs were drawn from norms collected by Cohen, Bousfield & Whitmarsh (1957). A good match in associative strength was obtained between taxonomic and associative pairs within each list, the means being respectively 4.72 and 4.80 in the HA list, and 2-49 and 2.48 in the LA list. Four different orders of each list of 24 words were prepared, random other than for these restrictions: ( a ) in no case did the two members of a related pair appear consecutively; (b) no word appeared twice in any of the first three or last three positions on a list. The lists were typed in capital letters for presentation in a Stowe Memory Drum, Model 459B.
Selection of subjects and assignment to groups T o avoid the usual confounding of thought disorder with schizophrenia, groups were to be selected on the basis of degree of thought disorder. The original plan was that hospital psychiatrists would rate their patients for presence and degree of thought disorder following Mayer-Gross, Slater & Roth (1960, pp. 244-246). Because this procedure would not permit under the circumstances a check on reliability, and because the patients with whom psychiatric staff were most familiar were too frequently unable to meet criteria for inclusion in the study, this plan was abandoned and Lovibond’s version of the Object Sorting Test
BOYDS. RICHARDS
278
(OST) was used to provide a criterion of presence or absence of thought disorder. Of the psychometric devices available, Lovibond's ' Schizotypy Scale ' appeared to provide the best combination of (a) high reliabilities (Lovibond, 1954;Lidz et al. 1963);(b) independence from measures of intelligence and verbal fluency (Romney, 1969);and (c) validity in terms of clinical judgement (Lovibond, 1954).A number of subjects were also rated by psychiatrists as a check on the scale's validity. The O S T was administered to 26 male psychiatric inpatients of the Ontario Hospital, Whitby, and to 34 male inpatients of the New Brunswick Provincial Hospital, Saint John. These were the first 60 subjects to meet selection criteria and complete the experimental procedures. The following selection criteria were applied : ( I ) English as principal language from an early age; (2) minimum education of six years; (3)no question of organic impairment, including alcoholism and lobotomy; (4)no electroshock treatment within four months of testing; (5) age between 18 and 65 years; (6)ability and willingness to read, write and follow instructions; (7)minimum forward digit span of five; (8) willingness of the physician in charge to withdraw psychoactive medication for at least 96 hours. (This latter would not eliminate the various medications from the body, but direct behavioural effects were lessened; the procedure was the best that could be achieved under the conditions of the research, and was thought better than simply ignoring the medication factor.) All O S T protocols were scored by a clinical psychologist with experience in administration and scoring of the test by Lovibond's instructions. Ten of the 60 protocols were also scored independently by the author; the interscorer reliability coefficient was 0.977.Four subjects who scored at the median (14) were discarded, leaving 28 scoring above the median -the T D group-and 28 scoring below the median-the N T D group. By chance (see 'Procedure'), 15 of the T D subjects had received the LA word list (the LA-TD group) and 13 had received the HA list (HA-TD group). Among N T D subjects, 13 had received the LA list (LA-NTD group) and 15 the HA list (HA-NTD group). T o produce four groups of 13 subjects each, two subjects were randomly eliminated from LA-TD and two from HA-NTD.
+
Table
I . Means ( X ) and standard deviations (s.D.) of the four groups on certain demographic variables
Non-thought disordered b LA HA
Variable Education (yr) Age (Yr)
x
9.6
S.D.
2.50
d S.D.
Vocabulary
a S.D.
Hospitalization (months) Hospitalization (Jmonths)
d S.D.
X S.D.
41'5 14-08 45'1 14'74 158.6 131.90 10.9 6.33
8.8 2.68 41'4 10.47 43'2 16.17 100'1
106.01 8 '5 5'32
Thought disordered LA
HA
10'1
9'5 2.62 39'5 10.37 39'2 13.09 118.5 82-39
3.12
45'1 8'39 42-0 13.89 142.3 99'85 10.9 4.81
10'1
4.06
Table I presents a comparison of the groups on the variables of education, age, vocabulary score, and total time in hospital. Hospitalization time was distributed with marked positive skew ; a square-root transformation provided a better approximation to normality, and both transformed and untransformed data are shown. Analyses of variance on all variables produced F values ranging from 0.34 to 0.70;the four groups were considered adequately matched. Four psychiatrists had provided ratings on 13 patients who eventually served as subjects. Seven of these were described as thought disordered; all seven scored above the median on the OST. Six were judged free of thought disorder; one of this number scored above the
Associative and Conceptual Organization in Thought Disorder
279
median. Fisher’s exact test yields a chance probability of 0.005 for this result, suggesting that the high scoring subjects would indeed be regarded as clinically thought-disordered. Procedure The subject was seen individually in two sessions, the first when he had been without psychotropic medication for at least three days. The Digit Span subtest of the Wechsler Adult Intelligence Scale was administered, followed by the OST. The second session took place approximately 24 hours later. After administration of the WAIS Vocabulary subtest, he was seated before the memory drum and instructed that his task was to read and recall a list of words. T h e words were presented at a rate of a word every 3 sec. At the end of the first presentation of the full list, he was immediately given a pencil and ruled sheet of paper and instructed to write down as many of the words as he could remember, in whatever order they occurred to him. A maximum of 5 min was permitted for recall; if a subject verbalized an inability to recall more words, he was encouraged once only to continue. If 5 min elapsed (a rare occurrence) or the subject expressed again his inability to produce more, his recall list was removed and the procedure repeated three times using three other orders of the list. RESULTS
The four recall protocols of each subject were scored for both amount of recall and amount of organization in each of the two types of item, taxonomic and associative. Organization The measure of organization used was the ratio of repetition (RR), calculated by the formula RR = 2r/n, where Y is the number of times that related words of a given type (taxonomic or associative) occur together in recall, and n is the total number of words of that type recalled. This clustering measure was devised by Marshall (1963) for cases where the related words are pairs rather than larger categories, and where different kinds of pairs are being compared. The RR is simply the proportion of recalled words of a given type that is clustered. The RR scores were analysed by means of a 2 x 2 x 2 x 4 split-plot analysis of variance (Kirk, 1968).Table 2 presents a summary. As would be expected, Associative Strength and Trials had significant effects. The HA list produced more clustering than the LA (means of 0.295 and 0.192)and clustering increased markedly with trials (means of 0 . 1 5 5 , 0.243, 0.259, 0.317).A difference in trend between T D and N T D groups was indicated by the Thought Disorder by Trials interaction and all of these effects are qualified by the significant four-way interaction. This interaction was expected; the hypothesized effects could be minimal on the first trial, since clustering develops over trials (Rosenberg, 1966) and pilot work suggested that this subject population would show a very low level of clustering initially. The pertinent data for the present report are those obtained on the fourth trial, and the simple effects of the other three variables were tested at the fourth level of the Trials variable. Mean RR scores on Trial 4 are presented in Table 3 and the results of the analysis in Table 4 . Clearly, the T D subjects imposed less organization on their recall. But since no interaction reached significance, the inferior clustering of T D groups relative to N T D groups was not differentially affected by either the conceptual relatedness of the words or by associative strength.
BOYDS. RICHARDS
280
Table
2.
Analysis of variance of RR scores over four trials
Source Between subjects: Associative strength (A) Thought disorder (C) AxC Subjects within groups (Ss wg) Within subjects : Pair type (B) AxB BxC AxBxC BxSswg Trials (D) AxD CxD AxCxD DxSswg BxD AxBxD BxCxD AxBxCxD B x D x Ss wg
M.S.
F
P
I
1'122
0'534 0.070 0.206
5'45 2'59
Associative and Conceptual Organization in Thought Disorder BY B O Y D S . R I C H A R D S University of New Brunswick, Fredericton, Canada Thought disorder has frequently been described either as a disturbance of associative response hierarchies or as an inability to deal with objects or events as representative of classes. The tendency of normal subjects to organize free recall by clustering associatively or conceptually related words suggested the recall task as a means to investigate these views of thought disorder. Two groups of psychiatric patients, one with high scores on Lovibond’s version of the OST, one with low (thought-disordered and non-thought-disordered, respectively), were presented with randomly ordered word lists containing pairs related associtively and pairs related taxonomically. Thought-disordered and non-thought-disordered groups were not differentiated by any tendency to cluster more of one kind of pair than another. Rather, the thought-disordered showed a general lack of organization in recall, and significantly less improvement over trials in amount recalled. The results do not support the view that thought disorder is specifically a disorder of concept use or conceptual mediation. Research needs to be addressed to variables which affect the activation or inhibition of mediational links in thinking.
Two major research approaches to thought disorder have survived several decades. Stemming from Bleuler’s (1950) classic description of associative disturbance in schizophrenia are investigations of word association responses. Following Benjamin, Cameron, Goldstein, and others (Kasanin, 1944), there have been many studies of concept identification and abstraction, measured in such varied ways as object sorting, proverb interpretation and similarities tests. Bleuler’s description suggests that the associative disturbance underlies the conceptual, but research has generally treated them as separate phenomena, and modern studies continue to focus on an associative disorder or an abstraction disorder (e.g. Johnston, 1974; Watson, 1974). A concept is commonly defined by common response to dissimilar objects or events (Kendler, 1968;Osgood, 1953). In concept learning or identification, correct performance requires that each of the examples of the concept elicit the same response: a generic term in object sorting or similarities tests, for example. Willner (1965, 1966; Willner & Reitz, 1965, 1966) has shown that such tests are partly solvable by free association to the stimulus items, and what looks like conceptual responding may be ‘merely’ associative. T o the extent that the same responses are associated with each of the stimuli, concept identification is facilitated, and thus conceptual responding is mediated by associations. Attempts to describe ordered thinking rely on one or another mediation construct (Berlyne, 1965; Osgood, 1953; Voss, 1969), and verbal associative mediators have been given a prominent place in such theories. I t may be asked whether clinical thought disorder might represent a functional loss of mediational processes. In the simplest verbal mediation paradigm, Lang & Luoto (1962) demonstrated 275
18-2
276
BOYDS. RICHARDS
facilitation of paired-associate learning among chronic schizophrenics, suggesting no loss of mediation of the forward response-chaining type (AB, BC, AC). There is a lack of evidence concerning less direct mediation paradigms (Jenkins, 1963) in either schizophrenia or thought disorder. Conceptual mediation, or abstraction, refers to those cases in which two or more different stimuli evoke the same response (dog and cat are conceptually related by their common associative response, animal). Studies of mediation using natural language stimuli are complicated by the fact that words which elicit the same response often tend to elicit each other directly: cat is a more frequent response to dog than animal is to either. A measure of conceptual mediation which can control to a large extent the degree of direct associative relationships and also has particular advantages for use with psychiatric populations is that of organization in free recall of verbal items. The study of organization imposed by subjects in the free recall of verbal material has come to occupy a large part of the verbal learning field (cf. Tulving & Donaldson, 1972). Early on, studies involved the random-order presentation of items related in various ways, with measures taken of the tendency for related items to ‘cluster’, that is, to occur in immediate succession in recall. This organization in recall was studied as a function of conceptual or taxonomic class relations among items (Bousfield, 1953), and as a function of strength of normative association between words (Jenkins & Russell, 1952). Both types of experimenter-defined structure induced greater than chance clustering. A number of studies demonstrated that taxonomically related words were more likely to be clustered than nontaxonomically related words with strength of direct association controlled (Marshall 1963; Bousfield & Puff, 1965; Cofer, 1966). Taxonomic word pairs tend to have more word association responses in common than do non-taxonomic pairs of equal direct associative strength. Table and chair may each elicit the responses sit, kitchen, furniture, wooden, as well as eliciting each other directly. Bousfield has used this characteristic of taxonomic pairs to explain their greater clustering, and has pointed out that the property of eliciting common responses is that which defines a concept (Bousfield, Steward & Cowan, 1964; Bousfield & Puff, 1965). The recall of randomly presented word stimuli appears to involve mediation processes similar to those required by the more traditional abstraction tasks. The recall task may, in fact, be the more subtle test of mediational adequacy. Clustering is more a measure of typical performance than of achievement, since subjects are not instructed to organize their recall. The measure of clustering can be reasonably independent of amount recalled, so that task motivation is less of a confounding factor. T o date, the only extensive published studies of organiza‘ion in recall with clinical populations have dealt with mentally retarded children and adults (Herriot, Green & McConkey, 1973). Since the completion of the present study, Koh, Kayton & Berry (1973) have reported a comparison of young ‘nonpsychotic schizophrenics’, non-schizophrenic psychiatric patients and university students in recall and organization. They used in one instance a measure of organization which reflects the tendency for a subject to recall the same words in contiguity on successive trials. Their apparently remitted schizophrenics showed less of this inter-trial repetition than either of the other groups, if the original list
Associative and Conceptual Organization in Thought Disorder
277 contained taxonomic categories; group differences disappeared on uncategorized lists. On the other hand, when the amount of actual clustering of taxonomically related words was measured, the difference between the two patient groups disappeared, both being inferior to normals. These findings are interesting and relevant, but because of the mixed results and the bases for subject selection, it is difficult to see the implications for an understanding of either schizophrenia or thought disorder. Bannister (1968) has given clear reasons for studying thought disorder independently of schizophrenia, and recent studies underline the necessity for doing so (Andreasen & Powers, 1974; Depue, 1974). The present study was intended to explore the relations among recall, organizational processes and thought disorder. The general hypothesis was that thought disorder represents a functional loss of the mediating processes which order thinking, although the associative repertories of thought-disordered subjects are essentially normal. By presenting thought-disordered and non-thought-disordered subjects with word lists containing pairs varying in both associative strength and taxonomic relatedness it was possible to test more specific hypotheses. These were (I) that the thought-disordered would show less clustering in recall as well as less recall, and (2) that this group difference would be greater in the case of taxonomically related words. The latter result would be predicted by theories which specifically posit a loss of abstracting or conceptual ability in schizophrenic thought disorder; the failure of conceptual mediation should lead to lessened use of relationships based on indirect associative links, but does not imply a difficulty in using direct associative links. METHOD Materials Two lists of words were made up from lists published by Bousfield & Puff (1965) and used by them in earlier studies of normal subjects. One list (HA list) consisted of 12 pairs of words of high direct associative strength, the other (LA list) contained 12 pairs of relatively low associative connexion. Associative strengths were calculated by Bousfield & Puff on the basis of the Connecticut Free Associational Norms, using logarithmic measures of cultural frequencies with which each member of a pair elicits the other as response. Within each list, HA and LA, were six pairs which are taxonomically related in addition to being associatively related. For convenience, the two types of pairs will be referred to as taxonomic and associative pairs. The taxonomic pairs were drawn from norms collected by Cohen, Bousfield & Whitmarsh (1957). A good match in associative strength was obtained between taxonomic and associative pairs within each list, the means being respectively 4.72 and 4.80 in the HA list, and 2-49 and 2.48 in the LA list. Four different orders of each list of 24 words were prepared, random other than for these restrictions: ( a ) in no case did the two members of a related pair appear consecutively; (b) no word appeared twice in any of the first three or last three positions on a list. The lists were typed in capital letters for presentation in a Stowe Memory Drum, Model 459B.
Selection of subjects and assignment to groups T o avoid the usual confounding of thought disorder with schizophrenia, groups were to be selected on the basis of degree of thought disorder. The original plan was that hospital psychiatrists would rate their patients for presence and degree of thought disorder following Mayer-Gross, Slater & Roth (1960, pp. 244-246). Because this procedure would not permit under the circumstances a check on reliability, and because the patients with whom psychiatric staff were most familiar were too frequently unable to meet criteria for inclusion in the study, this plan was abandoned and Lovibond’s version of the Object Sorting Test
BOYDS. RICHARDS
278
(OST) was used to provide a criterion of presence or absence of thought disorder. Of the psychometric devices available, Lovibond's ' Schizotypy Scale ' appeared to provide the best combination of (a) high reliabilities (Lovibond, 1954;Lidz et al. 1963);(b) independence from measures of intelligence and verbal fluency (Romney, 1969);and (c) validity in terms of clinical judgement (Lovibond, 1954).A number of subjects were also rated by psychiatrists as a check on the scale's validity. The O S T was administered to 26 male psychiatric inpatients of the Ontario Hospital, Whitby, and to 34 male inpatients of the New Brunswick Provincial Hospital, Saint John. These were the first 60 subjects to meet selection criteria and complete the experimental procedures. The following selection criteria were applied : ( I ) English as principal language from an early age; (2) minimum education of six years; (3)no question of organic impairment, including alcoholism and lobotomy; (4)no electroshock treatment within four months of testing; (5) age between 18 and 65 years; (6)ability and willingness to read, write and follow instructions; (7)minimum forward digit span of five; (8) willingness of the physician in charge to withdraw psychoactive medication for at least 96 hours. (This latter would not eliminate the various medications from the body, but direct behavioural effects were lessened; the procedure was the best that could be achieved under the conditions of the research, and was thought better than simply ignoring the medication factor.) All O S T protocols were scored by a clinical psychologist with experience in administration and scoring of the test by Lovibond's instructions. Ten of the 60 protocols were also scored independently by the author; the interscorer reliability coefficient was 0.977.Four subjects who scored at the median (14) were discarded, leaving 28 scoring above the median -the T D group-and 28 scoring below the median-the N T D group. By chance (see 'Procedure'), 15 of the T D subjects had received the LA word list (the LA-TD group) and 13 had received the HA list (HA-TD group). Among N T D subjects, 13 had received the LA list (LA-NTD group) and 15 the HA list (HA-NTD group). T o produce four groups of 13 subjects each, two subjects were randomly eliminated from LA-TD and two from HA-NTD.
+
Table
I . Means ( X ) and standard deviations (s.D.) of the four groups on certain demographic variables
Non-thought disordered b LA HA
Variable Education (yr) Age (Yr)
x
9.6
S.D.
2.50
d S.D.
Vocabulary
a S.D.
Hospitalization (months) Hospitalization (Jmonths)
d S.D.
X S.D.
41'5 14-08 45'1 14'74 158.6 131.90 10.9 6.33
8.8 2.68 41'4 10.47 43'2 16.17 100'1
106.01 8 '5 5'32
Thought disordered LA
HA
10'1
9'5 2.62 39'5 10.37 39'2 13.09 118.5 82-39
3.12
45'1 8'39 42-0 13.89 142.3 99'85 10.9 4.81
10'1
4.06
Table I presents a comparison of the groups on the variables of education, age, vocabulary score, and total time in hospital. Hospitalization time was distributed with marked positive skew ; a square-root transformation provided a better approximation to normality, and both transformed and untransformed data are shown. Analyses of variance on all variables produced F values ranging from 0.34 to 0.70;the four groups were considered adequately matched. Four psychiatrists had provided ratings on 13 patients who eventually served as subjects. Seven of these were described as thought disordered; all seven scored above the median on the OST. Six were judged free of thought disorder; one of this number scored above the
Associative and Conceptual Organization in Thought Disorder
279
median. Fisher’s exact test yields a chance probability of 0.005 for this result, suggesting that the high scoring subjects would indeed be regarded as clinically thought-disordered. Procedure The subject was seen individually in two sessions, the first when he had been without psychotropic medication for at least three days. The Digit Span subtest of the Wechsler Adult Intelligence Scale was administered, followed by the OST. The second session took place approximately 24 hours later. After administration of the WAIS Vocabulary subtest, he was seated before the memory drum and instructed that his task was to read and recall a list of words. T h e words were presented at a rate of a word every 3 sec. At the end of the first presentation of the full list, he was immediately given a pencil and ruled sheet of paper and instructed to write down as many of the words as he could remember, in whatever order they occurred to him. A maximum of 5 min was permitted for recall; if a subject verbalized an inability to recall more words, he was encouraged once only to continue. If 5 min elapsed (a rare occurrence) or the subject expressed again his inability to produce more, his recall list was removed and the procedure repeated three times using three other orders of the list. RESULTS
The four recall protocols of each subject were scored for both amount of recall and amount of organization in each of the two types of item, taxonomic and associative. Organization The measure of organization used was the ratio of repetition (RR), calculated by the formula RR = 2r/n, where Y is the number of times that related words of a given type (taxonomic or associative) occur together in recall, and n is the total number of words of that type recalled. This clustering measure was devised by Marshall (1963) for cases where the related words are pairs rather than larger categories, and where different kinds of pairs are being compared. The RR is simply the proportion of recalled words of a given type that is clustered. The RR scores were analysed by means of a 2 x 2 x 2 x 4 split-plot analysis of variance (Kirk, 1968).Table 2 presents a summary. As would be expected, Associative Strength and Trials had significant effects. The HA list produced more clustering than the LA (means of 0.295 and 0.192)and clustering increased markedly with trials (means of 0 . 1 5 5 , 0.243, 0.259, 0.317).A difference in trend between T D and N T D groups was indicated by the Thought Disorder by Trials interaction and all of these effects are qualified by the significant four-way interaction. This interaction was expected; the hypothesized effects could be minimal on the first trial, since clustering develops over trials (Rosenberg, 1966) and pilot work suggested that this subject population would show a very low level of clustering initially. The pertinent data for the present report are those obtained on the fourth trial, and the simple effects of the other three variables were tested at the fourth level of the Trials variable. Mean RR scores on Trial 4 are presented in Table 3 and the results of the analysis in Table 4 . Clearly, the T D subjects imposed less organization on their recall. But since no interaction reached significance, the inferior clustering of T D groups relative to N T D groups was not differentially affected by either the conceptual relatedness of the words or by associative strength.
BOYDS. RICHARDS
280
Table
2.
Analysis of variance of RR scores over four trials
Source Between subjects: Associative strength (A) Thought disorder (C) AxC Subjects within groups (Ss wg) Within subjects : Pair type (B) AxB BxC AxBxC BxSswg Trials (D) AxD CxD AxCxD DxSswg BxD AxBxD BxCxD AxBxCxD B x D x Ss wg
M.S.
F
P
I
1'122
0'534 0.070 0.206
5'45 2'59
