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
95
96
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
THOUGHT DISORDER IN SCHIZOPHRENIA
97
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
98
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?“).
THOUGHT DISORDER IN SCHIZOPHRENIA
99
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;: .05), though each differs from N subjects (Scheffe, p at least
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
95
96
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
THOUGHT DISORDER IN SCHIZOPHRENIA
97
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
98
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?“).
THOUGHT DISORDER IN SCHIZOPHRENIA
99
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;: .05), though each differs from N subjects (Scheffe, p at least
