Thought-process disorder in schizophrenia: The listener's task

BRAIN

AND

LANGUAGE

4, 95-114 (1977)

Thought-Process Disorder in Schizophrenia: The Listener’s Task S. R. ROCHESTER, J. R. MARTIN, University

AND

S. THURSTON

of Toronto

The task which the thought-disordered speaker poses for listeners was investigated using psycholinguistic and linguistic measures of interviews. Results show that clinically diagnosed samples of thought-disordered speech can be reliably distinguished from samples of both non-thought-disordered schizophrenic speech and normal utterances on the basis of (a) lay judges’ evaluations of coherence in transcripts and (b) linguistic variables measuring coherence. The linguistic measures which best predict judges’ evaluations indicate that, in thoughtdisordered samples, the speaker makes the listener’s task difficult (a) by asking the listener to search for information which is never clearly given and (b) by providing relatively few conjunctive links between clauses.

In 1908, Bleuler (1950) characterized association disorder as a basic symptom of schizophrenia. In the schizophrenias, he argued, there is a disruption in the thinking process. The associations which direct thoughts lose their connections so that the ideas expressed are unclear and vague. This formulation is the most widely accepted account of thought process disorder today1 (Freedman & Kaplan, 1967; Slater & Roth, 1969). Unfortunately, it is inadequate in several ways. Theoretically, the concept is obscure; it is not evident what “associations” are, how they come to be linked together, or where one might discover these linkages. Practically, the description is difficult to use (Kreitman, Sainsbury, Morrissey, The authors gratefully acknowledge the support of the Benevolent Foundation of Scottish Rite Freemasonry, Northern Jurisdiction, U.S.A. and the Clarke Institute Associates’ Research Fund. The authors express their profound appreciation to Dr. Alexander Bonkalo and Dr. Mary Seeman, both of the Department of Psychiatry of the University of Toronto, for their painstaking efforts in serving as clinical judges for thought disorder. We are grateful to Judith Rupp, Maryann Reynolds, Marilyn Friesen, Cathy Spegg, and Henry Pollard for their careful assistance in conducting this study and to Penny Lawler, Phillip and Mary Seeman. Howard Roback, Rita Anderson, and Joseph Jaffe for their discerning comments on an earlier draft of this paper. Address reprint requests to Dr. S. R. Rochester, Clarke Institute of Psychiatry, 250 College Street, Toronto, MST lR8, Canada. ’ Note, however, that “thought disorder” may not be peculiar to schizophrenia, as the Bleulerian formulation implies. There is evidence that thought disorder occurs in serious depressive illness (Ianzito, Cadoret, & Pugh, 1974), in severe mania (Carlson & Goodwin, 1973), and in many organic syndromes. In the present study, we are simply attempting to describe some characteristics of this phenomenon as it occurs in acute schizophrenia. To determine the specificity of our findings, we shall have to test a broad variety of patient groups. Copyright 411 rights

0 1977 by Academic Presb. Inc. of reproductmn nn any form reserved

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ROCHESTER,

MARTIN

AND THURSTON

Towers, & Scrivener, 1961; Foulds, Hope, McPherson, & Mayo, 1967); some of the events said to occur are clearly language acts (e.g., alliteration, neologisms, clang associations), while others call for complex sociolinguistic decisions from the listener (e.g., nonspecific looseness, “wooly” vagueness, inconsequential following of side issues). Finally, careful research on the concept is almost impossible to carry out because there is no systematic procedure for distinguishing instances of thought disorder from non-instances. In every investigation to date, a few clinicians sort thought-disordered patients from others on bases which are inadequately defined (Mellsop, Spelman, & Harrison, 1971; McPherson, Blackburn, D&fan, & McFadyen, 1973; Andreasen, Tsuang, & Canter, 1974). One exception to the practice of simply accepting the clinicians’ judgments of thought disorder is found in the work of Maher and his colleagues (Maher, McKean, & McLaughlin, 1966). They viewed the designation “thought disorder” as a problem for the observer and asked which cues are helpful to the observer in identifying thought disorder. Observers in this case were not only clinicians, but were laypersons as well. Both groups were able to distinguish documents written by thoughtdisordered (according to hospital records) schizophrenic patients from those written by non-thought-disordered schizophrenic patients. The cues which seemed useful in identifying thought-disordered documents were (a) sequences of highly associated words occurring at the ends of sentences, (b) relatively few self-references, and (c) concern with abstract themes. These findings, while valuable, still do not tell us how systematically to distinguish thought-disordered patients from others. We only know that thought-disordered patients produce significantly more events of one or another sort than do non-thought-disordered patients. We do not know the extent to which these production differences affect the observer’s experience of the discourse. For example, in Maher’s study, half the thought-disordered patients used more objects than subjects in their writing, but few (26%) non-thought-disordered writers followed this pattern. How does this fact affect the judgment that a text is thought disordered? One possibility is that a simple majority of objects to subjects prompts the identification of thought disorder. Or perhaps observers use the object/subject ratio in conjunction with the proportion of selfreferences to guide their decision making. A host of alternatives is possible. The point is that, with only standard statistical procedures, one must guess at the weight each variable exerts on the judges’ decisions. In the present paper, we have attempted to formulate a systematic description of operations underlying the identification of thought disorder. We begin with an unquestioningly operational definition of thought disorder: Thought-disordered patients (TD) are those called thought disordered by two senior clinicians; non-thought-disordered patients (NTD) are those so designated by the same clinicians. The patients and a

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group of normal volunteers (N) from the community are asked to speak individually in interviews. The interviews are transcribed and given to 10 lay judges who act as editors, indicating sections of the transcripts which seem incoherent or disruptive. We find that thejudges are highly successful in distinguishing the TD speakers from all other speakers. Moreover, when the transcripts are analyzed using linguistic variables, we are able to account for a substantial portion of the judges’ decisions. Finally, using these few linguistic variables, we can provide a decision rule for identifying most instances of thought disorder and for rejecting most non-instances. METHOD

Subjects The patient subjects were 40 schizophrenic patients interviewed during their first month in hospital at the Clarke Institute of Psychiatry, University of Toronto. Patients were invited to participate in this study when they received an admission diagnosis of schizophrenia uncomplicated by alcoholism or organic syndrome. Those who had received ECT within the previous 4 months were not approached. Although patients were invited to participate on the basis of initial diagnosis and were interviewed shortly thereafter, their performance was not analyzed until they had received a discharge diagnosis of schizophrenia arrived at by a consensus of the senior psychiatrist and other members of the treatment team. All patients thus diagnosed also met the criteria for a schizophrenic diagnosis of the New Haven Schizophrenic Index (Astrachan, Harrow, Adler, Brauer, Schwartz. Schwartz, & Tucker, 1972). The patients were relatively young acute schizophrenics. Their mean age was about 25 years. Their average number of previous hospitalizations was I .5, with a mean length of stay of about 2 months. All but two patients were on phenothiazine medication, receiving a mean chlorpromazine equivalent (Hollister, 1970)of 550 mgiday. About 80% of all patients had been receiving medication for no more than 3 weeks. Assessment of thought disorder. Thought disorder was said to be present when two psychiatrists, separately viewing an unstructured video-taped interview with a patient, concluded that the patient showed clear signs of thought process disorder. These two clinicians were not familiar with the cases and assessed thought disorder only on the basis of the video tape. They used Cancro’s (1969)Index of Formal Signs of Thought Disorder to guide their evaluations. This involves use of a four-point scale: 0, no characteristic thought process disorder; I, mild thought disorder (e.g., circumstantiality, literalness, concreteness); 2, moderate thought disorder (e.g., loosening of associations, punning, autistic intrusions); 3, severe thought disorder (e.g., perseverations, echolalia, extensive blocking, neologisms, incoherence). A total of 71 video-taped interviews was examined. Of these, ourjudges agreed that 20 showed no clear signs of thought disorder and that 20 showed clear signs. The former were designated NTD subjects, and the latter were designated TD subjects. Summing the judges’ ratings, we found that the median and modal values for TD subjects were both 4, and no TD subject received a rating of less than 3. The 20 NTD subjects are the primary control group in this study. They resemble the TD subjects in age, number of previous hospitalizations, mean length of present stay, and amount and duration of medication. In addition, a secondary control group of 20 normal volunteers from the community is included in this study. This group is included to provide an estimate of what normal performance is in the language analyses performed here. Since the normal subjects have no reported history of psychiatric disturbance, they cannot be compared directly to the schizophrenic patients: They have not been hospitalized, are not on

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ROCHESTER, MARTIN AND THURSTON TABLE 1 SUBJECT CHARACTERISTICS

ShipleyHartford

Education

Age Group

B

SD

B

SD

TD NTD N

24.3 26.8 29.9

6.4 7.9 10.9

11.2 11.9 15.0

2.6 2.6 2.1

x 101.5 104.1 117.8

SD 8.4 10.4 6.8

medication, and are not undergoing a major life crisis. However, the normal subjects are sufficiently similar to the schizophrenic subjects to permit us to make baseline estimates of performance. All subjects either were native English speakers or had adopted English by the age of 12. They were between the ages of 1.5and 52 years, had completed at least seven school grades, and were paid to participate in the study. Table 1 summarizes several salient characteristics ofour sample. The groups do not differ in composition according to sex($ = 2.9,d’ = 1;~ = .23) or age (one-way analysis of variance yieldsF(2,57) = 2.1 ,p > . 10). However, as might be expected, the patients’ education levels and IQ scores are lower than the normals’. Normals have about three more school grades than the patients (one-way analysis of variance yieldsF(5,57) = 13.4,~ < .OOl)and score about 10 points higher than patients on the Shipley-Hartford (tranformed to WAIS equivalents) (analysis of variance yields F(5,57) = 13.4, p < .OOl). Nevertheless, Scheffe tests indicate that TD and NTD subjects are homogeneous with regard to both education and 1Q level. With regard to social class variables, the patient groups were essentially similar to each other and different from control subjects. Occupational classifications revealed that 35% of TD, 35% of NTD, and 50% of N subjects had either service or professional skills and that 30% of each group were students. Two people said that they had no employment, and they were in the TD group. A total of five people worked in the home: Two were in the NTD group, three were in the N group, and none was in the TD group. With the exception of these latter categories, the patient groups are similar to each other and tend to be employed in occupations requiring less training than the normal subjects. With regard to employment generally, about one-third of TD and of NTD subjects were not usually employed, while none of N subjects fell into this category (this analysis excluded students and housewives). A noteworthy difference between the patient groups emerges, however, at the higher end of this scale: Only 7% of TD subjects, but 42% of NTD subjects and 54% of N subjects, report a steady employment history. The difference between N and patient subjects may be due to the fact that the former are about 3-6 years older than the latter. However, TD and NTD subjects are not more than a mean of 3 years apart and the difference here should probably be pursued. Finally, with regard to marital status, 80% of TD subjects, 90% of NTD subjects, and 50% of N subjects were single. Again, differences between patients and N subjects may reflect age differences. Inrerview. All subjects participated in an unstructured interview (with SR or ST) of about a 0.5-hr duration. The interview was video-taped for patients, but not for normal subjects (costs prohibited taping all subjects). Subject and interviewer sat facing each other, and the subject was told to speak about anything that was interesting. If he or she had dilfliculty beginning, topics were suggested (e.g., what you’ve been doing in the past 2 years, a trip you’d like to take, things which make you happy or sad). The interviewer spoke only to encourage the subject to continue, and all such comments were directed toward that goal (e.g., “And then what happened?” ” And how was that?“).

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Sampling Procedure Discourse was recorded through Uher M822 low impedance lavelier microphones input to a Uher Royal Deluxe stereophonic tape recorder at 7.5 ips. The stereo recordings permitted judges to listen separately to interviewer and subject. For each subject, 3-min speech samples were taken. These were about 468 words (SD = 113). Where possible, 3-min samples of uninterrupted speech were taken; otherwise, shorter samples were selected and combined. Ideally, samples from TD subjects would have been selected at random from the discourse. However, this procedure would ignore the fact that only small portions of the TD subjects’ discourse showed signs of thought disorder. Thus, for TD subjects, the most thoughtdisordered sections (as indicated by the two consultant clinicians’ comments) were selected. For other subjects, sections were selected at random.

Sentence Units The basic unit of analysis was the independent clause (any unit that can be generated from a noun phrase and verb phrase). Relative clauses, sentence complements, and other subordinate structures were treated as parts of this basic unit. For example, the following is one unit. (a) Sharon saw Ruth while she was in Ottawa.// Sentence modifiers were treated as separate sentence units, as were independent clauses linked by “and,” “or,” and “but.” This is shown in the following two sentences. (b) Snoopy is a human dog//which makes him a laughable character.// (c) A dog arrives on the scene with the usual barrel of wine around his neck//but this time with 25 cents written on it.// One coder (JM) analyzed typescripts of the utterances while listening to them on a tape recorder. A second coder (ST) separately analyzed typscripts from I8 subjects, 6 per group. Reliability between coders was high, ranging from 90-98% (mean = 94%).

ANALYSES

(1) Editing Task Is there any simple decision rule which permits an observer to identify most instances of thought disorder and to minimize the number of false identifications? In search of such a decision rule, we reasoned that clinical assessments of thought disorder rest largely on inferences made from patients’ speech. In particular, the clinician appears to make a judgment that the patient’s discourse is incoherent. If this is so, then the clinician’s decision with regard to thought disorder is of the same kind as any native speaker’s decision that an utterance is incoherent. We hypothesized, therefore, that lay judges asked to evaluate the flow of coherence of interview transcripts would be able to match the assessments of clinical judges. That is, lay judges should be able to differentiate thoughtdisordered from non-thought-disordered speakers. Method. Five male and five female volunteers, aged 20-35 years, with a mean of 15 years of education, were editors for interview transcripts. They were paid $3.00/hr and worked no longer than 4 hr/day. They were given

100

ROCHESTER, MARTIN AND THURSTON -la _ _ _

1. I’ve @ to find myself a linle wmen 2. who is my ei~ual 3. who’d like to who knOm how to embroider jeans preferably another Cancer 4 cause I em a Cancer 5. it’s my horoscopein the zodiac 6 in other wrds nothing can harm me 7. if I feel my own pain B they gave mea needleon the Queen’s birthday imagine 9. some guy namedTput it in for them and I I forgave him instantly you know 11. I wanted BP around the other time 12. I told B__ the next time you get heavy I’m gonna put a contract on you 13. and he left immediately 14 so we’re looking for the the source 15. now is the source comefrom the organization as the Russians believe

FIG. 1. Editing Task example showing one section from an interview with a thought-disordered subject (sentence units 8, 9, 14, and I5 were judged to be highly disruptive).

typed transcripts containing three to four selections from the interview tapes of each subject in this study. The selections were divided into a maximum of 15 numbered sentence units, as shown in Fig. 1. The several selections were presented in the order in which the subject spoke them. Each judge received a packet of selections for 60 subjects, a set of answer sheets, and a randomly determined order in which to read the transcripts. Judges were told to mark any unit which seemed to disrupt the flow of the passage. Editing Task:PrOportion of Highly Disruptive Units in Interviews of TD,NID, and N Speakers Thought-disorde;:
/

:fy&rm, .40

.60 .rJo Proportion of Group INGUI

ss l.M

FIG. 2. Cumulative proportion of highly disruptive units in interviews as a function of proportion of speakers per group.

THOUGHT DISORDER IN SCHIZOPHRENIA

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Results. Highly disruptive units are defined as those agreed upon by at least 70% of the judges. Figure 2 shows the cumulative proportion of units judged to be highly disruptive for each group of subjects. It is possible to make a decision rule based on these data which permits a high level of discrimination between subjects who are and are not judged to be thought disordered. We assessthe decision rule in terms of two probabilities: (a) the probability of correctly identifying a TD subject as being thought disordered, a “hit,” and (b) the probability of incorrectly identifying an NTD or N subject as being thought-disordered, a “false alarm.” An optimal decision rule in this case would be to say that anyone with 7% or more highly disruptive sentence units is thought disordered. This yields a hit rate of 75% and a false alarm rate of only 5% for NTD subjects and 0% for normals. This is clearly superior to the discrimination possible with Bannister and Fransella’s Repertory Grid Test (1967).* That widely used measure of thought disorder is commonly employed with a cutoff criterion of I 2 1000 and C 2 +0.49. If we follow this practice and call anyone who falls below the criterion thought disordered, we include only 57% of all clinically diagnosed thought-disordered subjects, but we include 31% of nonthought-disordered subjects and 10%of the normals. That is, using the Grid Test, there is a relatively low hit rate and a high false alarm rate. These findings suggest that the clinical phenomenon of process thought disorder can be related to the normal psychological experience of incoherence in discourse. Given this, we attempt to describe thought disorder as disruptions in the normal flow of discourse using linguistic measures. (2) Cohesion Analysis Measures of cohesion (Halliday & Hasan, 1976; Gutwinski, 1976)can be used to investigate nonstructural relationships between sentences. There are three sorts of cohesive ties between sentences that are of interest here: Reference, Conjunction, and Lexical Cohesion [for a detailed report of this analysis, see the reports of Martin and Rochester (1975) and Rochester and Martin, (in press)]. As Table 2 shows, Reference ties concern the relation between a cohesive element (e.g., a pronoun) and the explicit information (e.g., the original noun phrase needed to interpret that 2 In the Grid Test, the authors hypothesize that a loosening in construct systems is characteristic of thought process disorder in schizophrenic patients. To assess the coherence of a subject’s construct systems, the investigator presents eight photographs of men and women and asks the subject to rank order each photograph on six constructs (e.g., “kind,” “stupid, ” “selfish”). The subject then repeats the test, giving new rankings if desired. From this performance, “Intensity” and “Consistency” scores are calculated. These scores have been widely used to determine whether or not a given patient shows schizophrenic thought disorder (e.g., Frith & Lillie, 1972; Radley, 1974; but cf. Hill, 1976).

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ROCHESTER, MARTIN AND THURSTON TABLE 2 COHESION IN THREE CATEGORIES

Category Reference

Subcategory (1) Pronominal (2) Demonstrative (3) Comparative

Conjunction

(1) Additive (2) Adversative (3) Causal (4) Temporal (5) Continuative

Lexical

(1) Same root (2) Synonym (3) Superordinate (4) General item

Examples We met “Joy Adamson” and had dinner with her in Nairobi. We went to “a hostel” and oh that was a dreadful place. “Six guys” approach me. The last guy pulled knife on me in the park. I read a book in the past few days and I like it. They started out to England bur got captured on the way. It was a beautiful tree so I left it alone. My mother was in Ireland. Then she came over here. What kind of degree? Well, in one of the professions. Mother needed “independence.” She was always dependent on my father. I “got angry” at M. but I don’t often get mad. I love catching ‘fish.” I caught a bass last time. The “plane” hit some air pockets and the bloody thing went up and down.

’ Cohesive elements are in italics; tied-in information is indicated by the quotation marks.

element). Conjunction expresses a logical relation between clauses, and Lexical ties involve the repetition of either an item formed on the same root or a synonym. The number of cohesive ties in each of these categories was determined by two coders. The reliability of coding was 99% (range, 96 100%). Results. There are two sorts of results of interest here. First, schizophrenic speakers use less cohesion than normal speakers. As Table 3 shows, cohesive ties per cjause were 1.91 for TD subjects and 1.96for NTD subjects, while N speakers use 2.1 ties per clause. A two-way analysis of variance (groups x subjects within groups) yields F(2,57) = 5.9, p < .005. Scheffe tests reveal that each patient group differs (p < .005) from the normal group but not from each other. Second, TD speakers differ from other subjects in the kind of cohesion they employ. We examined the proportion of total cohesive ties for a speaker falling into each of the three cohesion categories (i.e., Reference, Conjunction, Lexical Cohesion). The proportions (shown in Table 3) were

THOUGHT DISORDER IN SCHIZOPHRENIA

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TABLE 3 DISTRIBUTION

OF COHESIVE

TIES

Proportion of ties per categorya Group

Reference

Conjunction

Lexical

Mean total of ties

Mean ties per clause

TD NTD N

.34 .33 .30

.23* .30 .36

.41 .34 .33

42.0 42.1 52.0’

1.91 1.96 2.1W

(1Proportions sum to less than 1.0 because two minor categories are not reported. b TD subjects are significantly different (Scheffe, p at least <.OOS) from NTD and N subjects, and the latter two groups do not differ from each other (Scheffe, p > .OS). c TD and NTD subjects do not differ from each other (Scheffe, p > .05), though each differs from N subjects (Scheffe, p at least <.005).

transformed with arc sines, and two-way analyses of variance were performed. Where F values yielded p < .Ol, Scheffe tests were done to assess differences between subject groups. Thought-disordered speakers use proportionately fewer conjunctions to form cohesive ties than do other subjects [F(2,57) = 11.6, p < .OOl]. There are no significant differences between NTD and N subjects. Conversely, TD subjects use more Lexical Cohesion than do the other two groups [F(2,57) = 4.5,~ < .05]. Again, NTD and N subjects do not differ. Finally, there are no significant differences among groups in the use of Reference. Discussion. There are significant differences in the way in which the two groups of schizophrenic speakers tie their sentences together. Thoughtdisordered subjects use relatively less Conjunction, a tying which seems to express logical relations between sentences. They use relatively more Lexical Cohesion, a tying accomplished primarily through single words. The conjunctive tie appears to involve more of the sentence relationships and hence constitutes a stronger bonding between sentences than does the lexical tie. Specifically, Martin (Note 2) has argued that Conjunction links a clause to other clauses (and to the situational context). The conjunctive tie, he argues, makes explicit the presuppositional dependencies between the clauses which are to be joined. Conjunctions guide the listener to those semantic relations which make the conjoined clauses relevant to each other. As a result, the conjunctive tie seems to be a particularly strong cohesive device. According to this formulation, we would expect discourse with an abundance of lexical ties and an undersupply of conjunctive ties to be loosely connected and somewhat difficult to follow. This, in fact, was the experience of our lay judges with the thought-disordered samples.

104

ROCHESTER, MARTIN AND THURSTON TABLE 4 CATEGORIES OF RETRIEVAL STRATEGIES”

Category Verbal

Location of referent Explicit verbal context

Example A donkey was loaded with salt and “he”

went to cross a river. Situational

Explicit situational context

I am reading “this paper” now.

Bridging

Implicit verbal context

There’s a house with two people standing in “the door.”

Addition

Not clear

A donkey was crossing “the other river.”

Ambiguous

Not clear

A commuter

and a skier are on a ski lift and “he” looks completely unconcerned.

a The referent is in italics; the quotation marks indicate the noun phrase which requires additional information.

(3) Analysis of Retrieval Strategies This analysis focuses specifically on problems the speaker poses for the listener. Interview materials were first divided into noun phrases by two coders (agreement between coders was 88.7%; range, 81-91%). Next, all noun phrases which required additional information to be understood were identified. At this stage, the two coders’ agreement was 85.3% (range, 70-97%). Finally, coders sorted the identified noun phrases into one offive categories according to the location of the additional information. Agreement in this sorting was 88.7% (range, 80-96%). The five categories of noun phrases according to location of their referents are shown in Table 4. There are two categories in which the referent information is explicitly presented. In Verbal Retrieval, the listener is referred in a straightforward manner to the verbal context (note that this is identical to the case of Reference examined in the foregoing Cohesion Analysis). The second explicit category, Situational Retrieval, occurs where the speaker points directly to the immediate situational context. There are three categories in which referent information is implicit. Haviland and Clark (1974) and Springston (1976) have distinguished these categories and have investigated the difficulties they pose for the listener. The most common implicit reference is Bridging. Here, the referent information (e.g., the door) does not refer directly to a prior noun phrase (e.g., a house), but is, nevertheless, accessible to a listener. The door falls within the semantic range of a house and listeners are relatively quick to understand sentences which involve such relationships.

105

THOUGHT DISORDER IN SCHIZOPHRENIA TABLE 5 DISTRIBUTION OF NOUN PHRASES IN FIVE RETRIEVAL CATEGORIES

Proportion of NP per category

Group

Verbal

Situational

TD NTD N

.42 .40 .50

.44 .55 ,396

Addition

Ambiguous

Mean total NP per speaker

.O?” .04 .03

.02” .oo .oo

31 33 36

Implicit reference

Explicit reference Bridging .04 .02 ,023”

n TD subjects are significantly different (Scheffk, p < .05) from NTD and N subjects, and the latter do not differ from each other. JJTD and NTD subjects do not differ from each other, though each differs from N subjects (Schefft5, p < .05).

Listeners are slow, however, in dealing with the remaining IWO categories: Addition and Ambiguous Reference. In the case of Addition, the listener is alerted to search for prior reference or additional information, but no apparent referent has been given in either the verbal or the situational context. The listener must therefore “add” information. In Ambiguous Reference, the listener is given more than one possible referent and must choose between referents with no clues from the speaker about which is intended. Results. For each subject, the total number of noun phrases requiring referents (and not included in other noun phrases) was computed. From this total, the proportion of noun phrases in each retrieval category was determined. Groups were compared in terms of the proportion of mean noun phrases falling into a given category. Two-way analyses of variance (groups x subjects within groups) were performed on the arc sine transforms of these proportions, and, where F values yielded p < .Ol, Scheffe tests were carried out to assess the significance of the differences between groups. The results are presented in Table 5. In explicit reference, schizophrenic subjects differ from normal speakers. Schizophrenic speakers use significantly more situational reference than do normal speakers [F(2,57) = 5.2, p < .Ol]. As Table 5 indicates, this tends to be balanced by a greater use of explicit verbal reference by normals. Where reference is implicit, normal subjects are more likely than are schizophrenic subjects to use the Bridging category [F(2,57) = 8.3, p < .OOl]. The remaining two retrieval categories, Addition and Ambiguous Reference, are used most frequently by TD subjects [Addition F(2,57) = 3.0, p < .05; Ambiguous Reference F(2,57) = 5.9, p < .005]. Normal and NTD speakers do not differ in their use of these two categories.

106

ROCHESTER. MARTIN AND THURSTON TABLE 6 STEPWISE DISCRIMINANT FUNCTION ANALYSIS FOR THOUGHT DISORDER

False alarms* (%I Variable Cohesion Conjunction Lexical Reference Verbal Situational Bridging Addition Ambiguous reference

Multivariate F statistic

Order entered

Hits” (%I

5.40t

2

55

3.97t

5

55

3.17t

7 6

60 60

NTD

N

30 5

20

10 10 25 10

15

15

10

20 20 10 15

10

15

a Hits are the percentage of TD subjects correctly identified as being TD. * False alarms are the percentage of NTD and N subjects incorrectly as being TD.

identified

3.54t 7.00* 4.38t

4.86t

All variables

1

I5

4 3

50 50 642

*p < .005. tp < .ool.

Discussion. These results suggest subtle differences in the task the three groups of speakers pose for the listener. The normal speaker makes the listener’s task easy by using relatively many explicit verbal references and by placing implicit verbal references within the immediate semantic range of the listener. In contrast, the schizophrenic speaker probably makes the listener’s task more difficult by using relatively few verbal references and by relying on references to the nonverbal context. Finally, the thought-disordered speaker seems to pose the most profound problem for the listener: No matter how long the listener searches, she or he will be unable to identify definitely some small number of the thought-disordered speaker’s references. (4) Discriminant Function Analysis The linguistic variables examined above can be formed into a single weighted composite score to distinguish TD speakers from all other subjects. Table 6 shows the results of such adiscriminant function analysis. Only two variables, Bridging and Conjunction, are needed to yield a hit rate of 55%. At this point, false alarms are still high, with 30% of NTD subjects and 15% of N subjects incorrectly identified as being thought disordered. When all six variables are used to form a weighted predictor combination,

107

THOUGHT DISORDER IN SCHIZOPHRENIA TABLE 7 COMPARISON

OF CLINICAL ASSESSMENTS OF THOUGHT THREE METHODS OF ANALYSIS

DISORDER

WITH

False alarm rate (%) Hit

Analysis Grid Test of thought disorder Editing task (10 lay judges) Linguistic variables

rate (%)

(20 TD subjects)

20 NTD subjects

20 N subjects

51

31

IO

75 60

5 IO

0 15

the hit rate rises and the false alarm rate drops to a more satisfactory level. At this stage, the chance of correctly identifying a TD subject is 60% and the false alarm rate is 10% for NTD and 15% for N subjects. Table 7 compares the discriminating power of these variables with that of other methods of assessing clinically defined thought disorder. Notice that a decision rule made on the basis of all six linguistic variables approaches, though does not match, the discriminating power of a rule based on the Editing Task. The rule derived from the Editing Task yields a hit rate which is 15% higher and a false alarm rate which is about 10% lower than the present assessment based on linguistic variables. The present rule, however, is superior to the discriminating power of the standard psychometric test for thought disorder, the Grid Test. (5) Multiple

Regression Analysis

To summarize briefly, the thought-disordered speaker can be differentiated from other speakers, both schizophrenic and normal, on the basis of (a) judges’ evaluations of the coherence of discourse and (b) a weighted combination of linguistic variables describing the discourse. We do not know, however, the extent to which linguistic variables contribute to the judges’ experience of incoherence. To estimate this, a multiple regression analysis was performed. The criterion variable was the proportion of highly disrupted sentence units to total sentence units for each subject on the Editing Task. Test variables included all of the Cohesion and Retrieval categories described above. Three variables emerge as useful predictors of judges’ evaluations of coherence. Addition accounts for 31% of the total variation in the criterion variable [F( 158) = 26.2,~ < .OOl], Conjunction accounts for 4.1% of that variation [F(2,57) = 3.52, p < .05], and Ambiguous Reference predicts 2.7% of the variation (F < 1). These effects can be taken as being indicators ofhow linguistic events are

108

ROCHESTER,

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AND THURSTON

experienced by the listener. Notice that the predictive value of a linguistic variable is not obvious from its distribution in the speech of the three subject groups. For example, consider two cases in which analyses of variance of individual variables yield modest F values (p < .05). In the case of Addition, TD subjects use this category only 3-4% more frequently than do other subjects, but this variable predicts 3 1% ofjudges’ evaluations of coherence. Lexical Cohesion, on the other hand, is used 13- 14% more often by TD speakers than by other subjects, but this variable accounts for only 0.2% of the variance in the criterion variable. When all of the Cohesion and Retrieval variables are included as predictors, it is possible to account for43% of total variation in the criterion variable. This is noteworthy, but indicates clearly that several aspects of the judges’ decision-making remain to be specified. GENERAL

DISCUSSION

The object of this study has been to describe thought process disorder from the point of view of the listener. Three findings are outstanding. (a) Lay judges can distinguish samples of thought-disordered speech from samples selected at random from the speech of other subjects. The judges can make this discrimination with an impressive 75% hit rate and a O-5% false alarm rate. This indicates that the native speaker of English, as well as the experienced clinician, perceives something “wrong” in the occasional incoherent sentences of the thought-disordered speaker. (b) Six linguistic variables can be used to distinguish the aberrant utterances of clinically diagnosed thought-disordered subjects from other speakers, with a 60% hit rate and a IO- 15%false alarm rate. That is, using a few characteristics of the speech, one can do almost as well as lay judges in deciding that something is wrong with the discourse. (c) The critical question, however, is not whether or not thoughtdisordered utterances can be separated from those of other subjects, but whether or not the bases on which the listener makes this distinction can be identified. We find that three linguistic variables predict about 38% of lay judges’ evaluations. Thus, these variables are informative of some, though not all, of the judges’ bases for decision-making. Clearly, a more comprehensive examination of thought-disordered speech is required. Along with the present variables, at least two other systems should be considered: (a) the system of intonation marking the information structure in the clause (Halliday, 1967, 1968) and (b) the structure by which verbs presuppose referent information (Kiparsky & Kiparsky, 1968; Karttunen, 1971). How Understandable is the Schizophrenic Speaker? In conjunction with these findings, two corollary points should be mentioned. First, it is important to note that the thought-disordered

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speakers we studied were not, in general, incoherent [contrary to what one might expect from Chaika’s (1575) report of a single patient]. Certainly it is not true that the schizophrenic speakers, as a whole, were incoherent. Much to the contrary, the acute schizophrenic speakers in this study produced essentially adequate discourse: As Fig. 1 shows, half the schizophrenic samples (from speakers with no clear signs of clinical thought disorder) are almost indistinguishable from the samples of normal controls. Furthermore, even those utterances which were singled out as being thought-disordered by our psychiatric judges were still not generally incoherent: That is, most (80%) of the thought-disordered samples had less than 16% of the clauses evaluated as highly disrupted, and in no sample were more than 30% of the clauses disrupted. The fact that schizophrenic subjects, even those who are thought disordered, are essentially adequate communicators should not be overlooked. It supports Fromkin’s (1575) excellent argument for the ordinariness of the linguistic basis of thought disorder and is therefore theoretically significant in understanding language aberrations. In addition, this general adequacy is clinically significant, for it demonstrates, as Joseph Jaffe (Note 1) has observed, that “a few swallows do make a summer.” That is, a very few aberrant instances are sufficient to prompt observers, whether lay people or highly trained clinicians, to the conclusion that something is amiss in the discourse. What Do We Know about Schizophrenic Speakers? The second corollary point concerns the interpretation of differences between groups. In this study, one could argue that there were two sorts of linguistic differences observed: those where the speakers were similar in socio-economic background and education and those where the speakers differed. We have thus far been emphasizing the linguistic differences between groups with essentially identical background variables, i.e., between schizophrenic speakers who were and were not judged to be thought disordered. These groups differed in two respects: in the type of cohesion they employed and in their use of unclear noun phrase referents. We have thus far neglected differences between groups with different backgrounds, that is, between schizophrenic speakers and normal speakers. Schizophrenic speakers differed from normal speakers in two respects: they used fewer cohesive bonds and more situational reference than did normal speakers. What are we to make of these schizophrenic vs. normal differences? Do they reflect cognitive differences and/or differences in education and/or differences in cultural background? We cannot answer these questions, since schizophrenia and lower socio-economic status (and lower education level) were confounded in the present study. However, we do have some additional data which permit a tentative reply. With regard to situational reference, it appears that at least part of this

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usage is due to the operation of factors involved in the cognitive effects of schizophrenia (or acute psychosis). This interpretation is suggested by findings with the same speakers in narratives and in the description and interpretation of cartoon stories (Rochester & Martin, in press). In the cartoon tasks, thought-disordered speakers differ reliably from NTD speakers, and NTD speakers differ from normals: The groups use 33, 20, and 14% situational reference, respectively [with ANOVA yielding F(2,57) = 7.51, p < .005, and Scheffe tests between groups yielding at leastp < .05]. In the narratives, little situational reference is used, but the data again suggest that TD speakers use more such reference (3%) than do NTD speakers (1%) or N speakers (0%). The fact that TD speakers use reliably more situational reference than do NTD speakers in cartoon tasks, and tend to use more such reference in narratives, suggests that social/educational background differences cannot account for all of the variability in the use of reference. At least part.of the use of situational reference seems to be due to cognitive factors related to the psychosis. At the same time, however, we know (e.g., Hawkins, 1973) that differences in the use of situational reference reflect social class variables. For example, Hawkins reports that working-class children in England use about twice as many referents in the situational context as do middle-class children. Since our schizophrenic speakers differ in social class from their normal controls, we can also expect this difference to affect the use of situational reference. In the present study, therefore, it seems tenable that the greater use of situational reference by schizophrenic speakers reflects the operation of factors related to both the disorder itself and the social/educational level of the speakers. With regard to the schizophrenic speakers’ relatively small proportion of cohesive ties, there is little additional information on which to formulate hypotheses. We did examine cohesion in narrative contexts (Martin & Rochester, 1975) and again found that schizophrenic speakers use fewer cohesive ties (2.9 and 3.1 ties per clause for TD and NTD speakers, respectively) than do normal speakers [3.8 ties per clause; ANOVA yields F(2,57) = 6.03, p < .OOS,and Scheffe tests between schizophrenic and normal groups yieldp < .05]. Thus, there is no evidence that TD speakers differ from NTD speakers and, therefore, there is no support for the view that acuity of the psychosis affects the operation of this variable. At the same time, we know of no studies relating the use of cohesive ties to social/educational level and consequently cannot determine how likely it is that background factors affect the quantity of cohesion used. Interpretation of this finding clearly requires more data. What Problems Does the Thought-Disordered Listener?

Speaker Pose for the

At this point, we can describe the thought-disordered speaker as nresenting the listener with two nroblems: (a) The sneaker alerts the

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listener to search for information which, in fact, is never given or is never given in unambiguous form and (b) the speaker ties clauses together with limited (lexical) bonds more frequently than with more extensive (conjunctive) bonds. The listener, in effect, has to work harder to understand a thought-disordered speaker. In the case of (a), the conscientious listener probably searches recent memory for the intended referent and listens selectively to the ongoing discourse just in case the referent is forthcoming. At the same time, the listener is going about his or her normal task of decoding the speaker’s sentences. If this portrayal is correct, then the listener is operating under a processing overload when trying to understand a thought-disordered speaker. In the case of (b), the listener must provide cohesive bonding between clauses. Again, this is information which would normally be provided by the speaker. This demand on the part of the thoughtdisordered speaker seems to be described by Cameron’s (1944) asyndetic thinking, in which there is a “marked paucity of genuinely causal links.” In place of well-knit sequences, Cameron explains: the best our schizophrenics were able to do was to throw in a cluster of more or less related elements. what they gave was only a half-organized collection of fragments instead of a functional unit. (p. 53).

Do the Results Fit with What Is Known about Thought Disorder? Taken in overview, how well do these findings fit with what is known about thought disorderin schizophrenia? In two respects, the fit seems to be good. First, we find that thought-disordered speakers are qualitatively similar to our other subjects. That is, with the possible exception of Ambiguous Reference, all of the categories are used by all of the subjects. This is similar to the observation that famous authors often use devices identical to those found in patients diagnosed as being thought disordered (Andreasen, Tsuang, & Canter, 1974). It is also consistent with reports (Gerver, 1967; Truscott, 1970; Rochester, Harris, & Seeman, 1973; Carpenter, 1976) that schizophrenic subjects use syntax in the same manner as do normal subjects. Second, there is some evidence (Rochester, in press; Rochester, Thurston, & Rupp, in press) that the results found here are related to the inefficient use of processing time by thought-disordered speakers. This explanation has been put forward to account for the visual information processing of thought-disordered subjects (Holzman, Proctor, Levy, Yasillo, Meltzer, & Hurt, 1974). The central result of the present study, however, has not been investigated systematically. This result suggests an interpersonal failure on the part of the thought-disordered speaker: The speaker fails to take the point of view of the listener into account. This failure distinguishes the thought-disordered speaker not only from normal subjects but from other schizophrenic speakers as well. It has been described in the clinical literature as a failure of consensual validation (Sullivan, 1944) and as disarticulation from the social group (Cameron, 1944).

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However, there have been no objective measures of these effects. With the procedures described here, it should be possible to investigate systematically the interpersonal aspects of thought-disordered speech. For example, we may ask whether the thought-disordered speaker always fails to take the listener’s perspective into account or whether this happens only under stress. We may inquire into the nature of that stress, asking whether it depends on the patient’s prognosis (DeWolfe, 1974), on family relationships (Trunnel, 1965), and/or on the particular relationship between the speaker and listener. REFERENCES Andreasen, N. J., Tsuang, M. T., & Canter, A. 1974.The significance of thought disorder in diagnostic evaluations. Comprehensive Psychiatry, 15, 27-34. Astrachan, B. M., Harrow, M., Adler, D., Brauer, L., Schwartz, A., Schwartz, C., & Tucker, G. 1972. A checklist for the diagnosis of schizophrenia. The British Journal of Psychiatry,

121, 529-541.

Bannister, D., & Fransella, F. 1967.Grid test ofschizophrenic thought disorder. Bamstaple, England: Psychological Test Publications. orthe group ofschizophrenias. New York: International Bleuler, E. 1950.Dementiapraecox, Universities Press. Cameron, N. 1944. Experimental analysis of schizophrenic thinking. In J. S. Kasanin (Ed.), Language and thought in schizophrenia. Berkeley: University of California Press. Cancro, R. 1969.Prospective prediction of hospital stay in schizophrenia. Archives ofGeneral Psychiatry,

83, 278-284.

Carlson, G. A., & Goodwin, F. K. 1973.The stages of mania. Archives of General Psychiatry, 28, 221-228. Carpenter, M. D. 1976. Sensitivity to syntactic structure. Good versus pre-morbid schizophrenics. Journal of Abnormal Psychology, 85(l), 41-50. Chaika, E. 1975. A linguist looks at “schizophrenic” language. Brain and Language, 1, 257-276. DeWolfe, A. S. 1974. Coding of cognitive input in delusional patients. Journal of Abnormal Psychology, 20, 541-546. Foulds, G. A., Hope, K., McPherson, F. M., & Mayo, P. R. 1967.Cognitive disorder among the schizophrenias. I. The validity of some tests of thought-process disorder. British Journal

of Psychiatry,

113,1361-1368.

Freedman, A. M., & Kaplan, H. I. 1%7. Comprehensive rexrbook ofpsychiarry. Baltimore: Williams & Wilkins. Frith, C. D., & Lillie, F. J. 1972.Why does the Repertory Grid Test indicate thought disorder? British Journal

of Psychiatry,

121, 41-43.

Fromkin, V. A. 1975. A linguist looks at “A linguist looks at ‘schizophrenic language’ “. Bruin and Language,

2(4), 498-503.

Gerver, D. 1967. Linguistic rules and the perception and recall of speech by schizophrenic patients. British Journal of Social and Clinical Psychology, 6, 204-211. Gutwinski, W. F. 1976. Cohesion in literary rexrs. The Hague: Mouton. Halliday, M. A. K. 1967.Znronarion and grammar in Erirish English. The Hague: Mouton. Halliday, M. A. K. 1968.Notes on transitivity and theme in English. Journaloflinguisrics, 4, 179-216.

THOUGHT

DISORDER IN SCHIZOPHRENIA

113

Halliday, M. A. K., & Hasan, R. 1976. Cohesion in spoken and written English. London: Longmans. Haviland, S. E., & Clark, H. H. 1974. What’s new? Acquiring information as a process in comprehension. Journal of Verbal Learning and Verbal Behavior, 13, 512-521. Hawkins, P. R. 1973. The influence of sex, social class and pause location in the hesitation phenomena of seven-year-old children. In B. Bernstein (Ed.). Primary socialization, language and education: Class, codes and control. Boston: Routledge & Kegan Paul. Pp. 235-250. Hill, A. B. 1976. Validity and clinical utility of the Grid Test of schizophrenic thought disorder. British Journal of Psychiatry, 126, 25 t-254. Hollister, L. E. 1970. Choice of antipsychotic drugs. American Journal of Psychiatry, 127, l86- 190. Holzman, P. S., Proctor, L. R., Levy, L., Yasillo, N. J., Meltzer, H. Y., & Hurt, S. W. 1974. Eye-tracking dysfunctions in schizophrenic patients and their relatives. Archives of General Psychiatry,

31, l43- 151.

Ianzito, B. M., Cadoret, C. J., &Pugh, D. P. 1974.Thought disorder in depression. American Journal

of Psychiatry,

131(6), 703-707.

Karttunen, L. 1971. Implicative verbs. Language, 47, 340-358. Kiparsky, P., & Kiparsky, C. 1968. Fact. In M. Bierwisch & K. E. Heidolph (Eds.), Recent advances in linguistics. The Hague: Mouton. Kreitman, N., Sainsbury, P., Morrissey, J., Towers, J.,& Scrivener, J. 1961.The reliability of psychiatric assessment: An analysis. Journal of Mental Science, 107, 887-908. Maher, B. A., McKean, K. 0.. &McLaughlin, B. 1966.Studiesin psychotic language. In P. J. Stone, D. C. Dunphy, M. S. Smith, & D. M. Ogilvie (Eds.), The general inquirer. Cambridge, Mass.: M.I.T. Press. Martin, J. R., &Rochester, S. R. 1975.Cohesion and reference in schizophrenic speech. In A. Makkai & V. Makkai (Eds.), The $rst LACUS f orum. Columbia, S. C.: Hornbeam Press. Pp. 302-31 I. McPherson, F. M., Blackburn, I. M., Draffan, J. W., & McFadyen, M. 1973.A further study of the Grid Test of thought disorder. British Journal of Social and Clinical Psychology, 12, 420-427.

Mellsop, G. W., Spelman, M. S., & Harrison, A. W. 1971.The performance of manic patients on the ‘Grid test for schizophrenic thought-disorder.’ British Journal of Psychiatry. 118, 671-673.

Radley, A. R. 1974. Schizophrenic thought disorder and the nature of personal constructs. British Journal

of Social and Clinical

Psychology,

13, 315-327.

Rochester, S. R. In press. Are language disorders in acute schizophrenia actually information processing problems? Journal of Psychiatric Research. Rochester, S. R., Harris, J., & Seeman, M. V. 1973. Sentence processing in schizophrenic listeners. Journal of Abnormal Psychology, 3, 350-356. Rochester, S. R., & Martin, J. R. In press. The art of referring: The speaker’s use of noun phrases to instruct the listener. In R. Freedle (Ed.), Discourse comprehension and New York: L. E. Erlbaum Associates. production. Rochester, S. R., Thurston, S., & Rupp, J. In press. Hesitations as clues to failures in coherence: A study of the thought-disordered speaker. In S. Rosenberg (Ed.), Sentenceproduction: Developments in theory andresearch. New York: L. E. Erlbaum Associates. Slater, E., & Roth, M. 1969. Clinical psychiatry. London: Cassel Press. Springston, F. J. 1976. Some cognitive aspects of presupposed conferential anaphora. Ph.D. dissertation, Stanford University.

114

ROCHESTER,

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AND THURSTON

Sullivan, H. S. 1944. The language of schizophrenia. In J. S. Kasanin (Ed.), Language and rhoughf in schizophrenia. Berkeley: University of California Press. Truscott, I. P. 1970.Contextual constraint and schizophrenic language. Journnl of Consulting and Clinical Psychology, 35, 189-194. Trunnel, T. L. 1965. Thought disturbance in schizophrenia. Archives of General Psychiatry, 13, 9- 18.

REFERENCE

NOTES

I. Jaffe, J. Personal communication, May 8, 1976. 2. Martin, J. R. 1976. Three kinds of phoricity in English text. Paper presented at the Third Systemic Workshop, Nottingham, England. (Copies are available through Dr. S. R. Rochester).