Communication deficits: assessment of subjects with frontal lobe
Transcription
Communication deficits: assessment of subjects with frontal lobe
PREPRINT Bernicot, J., & Dardier, V. (2001). Communication deficits : assessment of frontal lobe damage subjects in an interview setting. International Journal of Language Communication Disorders, 36(2), 245-263. Communication deficits: assessment of subjects with frontal lobe damage in an interview setting Josie Bernicot and Virginie Dardier Laboratoire de Psychologie Langage et Cognition (LaCo) Université de Poitiers - CNRS MSHS, 99 avenue du Recteur Pineau - 86022 Poitiers Cedex, France Tel: 33.5.49.45.32.44 - 33.5.49.45.46.10 Fax: 33.5.49.45.46.16 email: [email protected] May 2000 2 Biographical notes on the authors Josie Bernicot is a professor of developmental psychology at Poitiers University. She is also head of the "Pragmatics of Communication" research team at the Language and Cognition Laboratory (LaCo, Poitiers University/CNRS). Her present research focuses on the field of developmental pragmatics. She has published theoretical and experimental articles on the following themes: verb acquisition by children, metaphors, the production and comprehension of speech acts, metapragmatics, transition from the nonlinguistic period to the linguistic period, input and pragmatic development, and pathologies and pragmatic development. Virginie Dardier is writing her Ph D at the University of Paris 5 and is a member of the Language and Cognition Laboratory (LaCo, Poitiers University/CNRS). She was granted a scholarship from the Ministry of Higher Education. Her dissertation is on pragmatic communication deficits in frontal-lobe damaged patients. Generally speaking, her studies deal with the fields of pragmatics and developmental pragmatics, with special interest in brain injuries. 3 Abstract This paper is about communication deficits in an interview setting among adolescents with frontal lobe damage. One of the predominant characteristics of these patients is difficulty taking the context into account. Pragmatic theories, which attempt to clarify the link between the formal structure of language and the extra-linguistic context (such as the interlocutor's characteristics or strategies), may help provide insight into the difficulties of these patients. An interview setting, viewed here as a communication situation, is governed by an interaction format based on specific cooperative principles. In this study, the results of subjects with frontal lobe damage (in the role of interviewee) were first compared with those of normal subjects in an interview situation. Three pragmatic indexes were considered: the number of utterances per speaking turn (speech quantity), amount of digression (keeping to the topic or predefined subject of conversation shared by the interlocutors) and prevalence of withinsubject contingency speaking turns without an intervening remark by the interviewer (topic development). Secondly, we attempted to determine whether the patients' discourse was dependent upon the interviewer's conversational strategy (structured, non-structured, or alternating). The results clearly point out the extent of the difficulty frontal lobe patients have conforming to the rules of the interview situation, whether regarding the amount of speech they produce or their ability to keep within and/or development of the topic of conversation. The data also indicated that the patients' linguistic productions varied with the interviewer's strategy. The structured strategy did not always give rise to the best performance: while the unstructured and alternating strategies allowed patients to produce more utterances per speaking turn, the alternating strategy enabled better development of the interview topic. These results suggest that such variations could be put to fruitful use in remedial techniques. Keywords: Frontal lobe lesions - Communication deficits - Interview paradigm Communication formats - Conversational strategies - Pragmatics 4 Introduction Communication deficits are often found in subjects with frontal lobe damage. Our first goal was to conduct a fine-grained analysis of these deficits during language use in a social interaction context. Pragmatic theories which attempt to clarify the link between the formal structure of language and the extra-linguistic context may help improve our understanding of how hard it is for these patients to communicate (Austin, 1962; Levinson, 1983; Searle, 1969; Searle & Vanderveken, 1985; Sperber & Wilson, 1986; Vanderveken, 1990; Verschueren, 1998; Verschueren, Östman & Blommaert, 1995). In the present study, we looked at the characteristics of the discourse of subjects with frontal lobe damage in an interview situation, where various executive functions are necessary to achieve satisfactory performance. The results of subjects with frontal lobe damage on various pragmatic indexes were compared with those of normal subjects during an interview. The second goal of this study was to determine whether the patients' discourse is dependent upon the characteristics of the discourse of their conversation partner. This aspect of the study is important for choosing and improving therapeutic techniques. These two goals were achieved by analyzing the language and communication deficits of patients with frontal lobe damage, determining what pragmatic indexes could be used to capture the flow of conversation, and considering the different remediation techniques used. Language and communication deficits in patients with frontal lobe damage As early as 1963, Luria had already suggested that the frontal lobe was involved in various cognitive functions. Since then, Levin, Heisenberg and Benton (1991) showed that the prefrontal cortex coordinates many of the executive functions an individual needs to autonomously carry out a variety of activities (planning and programming action). For Shallice and Burgess (1996), the prefrontal cortex is what enables the individual to build a mental representation of the outside world at the same time as it integrates emotions and motivations. Behavioural dysfunction following frontal lobe damage is one of the obstacles to the rehabilitation and the social and occupational reintegration of these patients (Bond & Godfrey, 1997). Among the dysfunctions (see Fuster, 1999), we find personality disorders, motor and attention deficits (Brooks, 1984; Eslinger & Damasio, 1985), and language impairment (Prigatano, Roueche & Fordyce, 1985). Wapner, Hamby and Gardner (1981) and Kaczmarek (1984) showed that phonological and syntactic abilities remain globally intact. However, certain frontal lesions have been shown to affect verbal fluency (Stuss, Alexander, Hamer et al., 1998). Moreover, some studies suggest that the prefrontal areas play an important role in lexical-semantic processing (Swick, 1998). 5 As a whole, the research has shown that pragmatic and paralinguistic skills are impaired in patients with frontal lobe damage. According to Penn and Cleary (1988), frontal-damaged patients have a general tendency to oversimplify what they have to say and are excessively redundant. They exhibit reduced speech spontaneity and slow ideation (Mentis & Prutting, 1987) and there is also evidence of reduced production (Coelho, Liles & Duffy, 1991). In addition, they appear to suffer from several conversational disorders including attention deficits, inattentiveness towards the interlocutor, and difficulty carrying on a conversation (Marsh & Knight, 1991). Mentis and Prutting (1991) and Bond and Godfrey (1997) noted that the topic changes of subjects with frontal lobe damage during a conversation are often inappropriate, and that their discourse is filled with inappropriate expressions. Their impairment also concerns the function of inferential processes, for example in comprehending irony (McDonald & Pearce, 1996) or understanding ambiguous advertisements (Pearce, McDonald & Coltheard, 1998). Mood seems to be highly affected in patients with right frontal lobe damage (Shammi & Stuss, 1999): they appear to react less, with diminished physical or emotional responses (laughter and smiling). Dennis, Barnes, Wilkinson et al. (1998) supplemented these studies in showing that in school-aged children, frontal lobe contusions were associated with poor understanding of deceptive emotion (in short narratives). Peter (1995, 1999) noted that other individuals addressing these patients often gear their discourse to the brain-damaged individual's level by adopting various conversational strategies. However, Peter (1995, 1999) contends that using such structuring frameworks is not only constraining for the other person, but may also be frustrating for the patient. It would therefore seem worthwhile to determine how effective such conversational strategies actually are, and whether they genuinely improve the quality of exchanges with subjects suffering from frontal lobe damage. Conversation, communication formats and pragmatic indexes Although the pragmatic approaches do not currently form a unified entity, they nonetheless agree on the following postulate: language is produced and interpreted via a set of conventions and knowledge that are shared by the speaker and the listener. Variations in utterances are not considered to be random, but linked instead to the social relationship between the interlocutors and their respective psychological states (for experimental illustrations, see Laval & Bernicot, 1999; Marcos & Bernicot, 1994, 1997; Ninio & Snow, 1996). This point of view is clearly based on a "top-down" approach to conversation, integrating the data into a predetermined framework of rules and units. In a pragmatic framework, Bruner (1983, 1990) defined an exchange between two individuals as a joint action which he calls a "format". This concept is very useful for defining the different types of conversation. A format is the pattern or model of a social relation, and requires the application of rules by both interlocutors (repetition rules, clarification rules, etc.). In a given context, the 6 two conversing partners thus participate in building the interaction format. During an interaction, the partners' intentions are not necessarily the same, but their expectations must be contingent (Bernicot, 1994). Every type of conversation is governed by particular rules that involve the cooperation of both partners (Grice, 1989). These cooperative principles clearly apply to the interview situation, where both interlocutors must be able to implement the pragmatic skills required by the interview format. The interviewer's role consists of encouraging the interviewee to speak, and assessing the relevance of what he/she says in order to bring the conversation back to the initial interview topic whenever necessary. The interviewee's task is to try not to digress and to organise his/her discourse in order to answer in a way that meets the other person's expectations. The pragmatic approaches propose a variety of indexes for assessing the unfolding of a conversation between two partners and for measuring any deficits or differences in populations with disorders (Kerbel & Grunwell, 1998a, 1998b; Leinonen & Kerbel, 1999). Some of the measures used are speech quantity indexes (number of speaking turns and utterances, number of utterances per speaking turn), indicators of the social functions fulfilled (distribution across situations of speech acts such as assertives, directives and commissives), and contingency indexes indicating the extent to which speakers adapt to their partners and/or to the communication situation. An utterance is considered to be between-subject contingent when its topic is the same as in the utterance just made by the other person (Bernicot & Roux, 1999; Hoff-Ginsberg, 1994). An utterance is regarded as within-subject contingent when its topic is the same as in the utterance just made by the speaker him/herself (Bernicot & Roux, 1999). These indexes can account for the overall structure of a subject's discourse and for his/her ability to converse in a way that meets the demands of the other speaker and/or the requirements of the situation. Patients with frontal lobe damage, communication deficits and remediation According to McTear and Conti-Ramsden (1992), one of the aims of pragmatic research is to precisely define the nature of the pragmatic difficulties associated with each disorder under study. The difficulties in question are not necessarily rooted in linguistic dysfunction, but may stem from general problems in extracting and inferring information from the context (Leinonen & Letts, 1997). For McDonald (1992), the contribution of the cognitive-pragmatic approach is twofold: (1) it enables differentiation between the various communication contexts and the resulting pragmatic constraints (which vary across contexts) and (2) it may turn out to be useful in evaluating the different types of therapy proposed to these patients. For Law (1997), the question of how to assess a subject's impairment is a fundamental one in the study of communication deficits. Moreover, therapy appears to be more effective when it takes place in a general learning context. There are many different therapy techniques for subjects with frontal lobe damage; substitution or compensation by means of external aids is the oldest one used. Despite its 7 apparently positive contribution, however, this type of assistance may turn out to be unsuitable because the patient plays a passive and non-stimulating role. Ylvisaker and Szekeres (1989) showed that the use of gradual feedback can help subjects with brain injury to improve their performance and learn more appropriate behaviours. Recent studies on the conversations of aphasic patients during therapy (Kagan, 1999; Kagan & Gailey, 1993) or in everyday situations (Laasko & Klippi, 1999) have shown that a conversation can work despite aphasia: the other person must consider the aphasic speaker as a real participant in the conversation and establish with him/her the collaboration rules used. It has been shown, for example, that in conversations of the problem-solving type (Laasko & Klippi, 1999), the phases of the conversation are the same with aphasic patients as with normal subjects and that aphasic speakers prefer self-repair in the same way ordinary non-aphasic people do. Peter's (1995, 1999) conclusions reflect this point of view, that providing a framework structured by others may turn out to be ineffective for a patient with frontal lobe damage. Aims and general hypotheses This study had two major goals: to precisely analyze deficits in the pragmatic aspects of language use in subjects with frontal lobe damage, and to assess their ability to adapt to the discourse characteristics of their addressee. In an attempt to both supplement and refine the results of prior research in this field (Bond & Godfrey, 1997; Dennis, Barnes, Wilkinson & al. 1998; McDonald & Pearce, 1996; Marsh & Knight, 1991; Mentis & Prutting, 1991; Pearce, McDonald & Coltheard, 1998; Shammi & Stuss, 1999), we chose to work in the area of conversational skills, and more specifically, on the interview setting. Participating in an interview can be regarded as a "frontal" task since it requires the implementation of specific cognitive capacities and executive functions ensured by the frontal lobe. Indeed, to achieve a successful exchange, a subject must be able to (1) get involved in the dialogue and take initiatives (volition), (2) understand not only the primary and secondary goals of the conversation, but also the necessary steps for constructing sound argumentation (planning), (3) keep the primary goal of the exchange in mind (goal-oriented action), and (4) assess the relevance of his/her discourse in order to modify its content (verification of the effectiveness of one's speech acts). Furthermore, this paradigm offers the possibility of studying subjects in a natural setting, where systematic analyses can still be conducted using specific pragmatic indexes already validated in research on normal communication. To achieve our first goal, we used various pragmatic indexes (such as speaking turns, digressions, and contingency) to determine the characteristic features of the discourse of subjects with frontal lobe damage during an interview. This communication situation is governed by an interaction format based on specific cooperative principles. The interviewer defines the conversation topic, which the interviewee must develop. Consequently, this format is characterised by an imbalance in the speech quantity of the two interlocutors. The interviewee must speak more often and longer than the interviewer. In addition, the 8 interviewee must make few digressions and come quickly back to the topic of conversation. Communication problems already noted in subjects with frontal lobe damage in a conversational setting suggest that executive dysfunction is likely to be observed during an interview. Compared to normal subjects, subjects with frontal lobe damage may not be able to meet the requirements of the interview format. However, contextual variations such as interlocutor familiarity (Peter, 1995; 1999) have been shown to affect a patient's discourse. Thus, we can assume that the pragmatic indexes of subjects with frontal lobe damage depend upon the conversational strategy adopted by the interviewer, who may provide variable amounts of outside help to the patient. Even if braindamaged patients are unable to abide by the cooperative principles that govern an interview situation, they should nevertheless exhibit some pragmatic skills, in accordance with the conversational strategy used by the partner. If this hypothesis turns out to be true, then we can contend that the interviewer's use of different exchange strategies gives patients the opportunity to exercise different pragmatic skills. We could then suggest that therapeutic techniques be geared more towards the exercise of skills than towards strict framing of the conversation. Method Subjects The experimental group (see Table 1) consisted of nine brain-damaged adolescents and young adults (6 males and 3 females). Three had a predominantly right frontal lesion, four had a bilateral frontal lesion, and two had a predominantly left frontal lesion. The brain damage had occurred at least three years earlier for all subjects, and the mean time since the accident for the group as a whole was 5 years 8 months. The age range was 15 to 24 years, with a group mean of 18;8. The subjects' IQ's were above 70 (normality criterion set by the World Health Organisation), with a group mean of 86 (range: 74-97). They were all attending school at an institute for motor learning in the Parisian area. The control group (see Table 1) was made up of nine normal adolescents and young adults who were matched to the subjects with frontal lobe damage on three variables: age, sex and socio-economic class (defined by the parents' occupations). In the light of our goals and the characteristics of frontal-lobe damaged patients, matching the experimental and control groups on IQ did not seem relevant. The subjects with frontal lobe damage had a mean IQ of 86 due to their discrepant performance on the different subtests: they obtained high scores in some subtests and mediocre scores on others. In contrast, normal subjects with an IQ of 86 have a uniform profile across subtests: they obtain poor scores on all subtests. It is important in making comparisons between brain-damaged patients and normal subjects that the two groups be equivalent on all other factors. Before the accident, all our brain-damaged subjects had a "normal" academic record, which is indicative of a mean IQ of 100 (or above), so comparing them with "normal" subjects is legitimate. 9 The results are analyzed by comparing the mean tendencies of the two groups. There were not enough subjects in the experimental group to form subgroups and analyze the relationships between their performance and the exact locations of the frontal lobe lesions. Insert Table 1 about here Procedure Subjects volunteered to participate as an interviewee in three interviews to be held over a three-week period. The experimenter, a young psychologist who knew the subjects, acted as the interviewer, proposing specific topics of discussion. In each new interview with a given participant, the experimenter changed the way she related to the interviewee by adopting a specific conversational strategy. When the "structured" strategy was used, the experimenter did not let the patient digress; when the "unstructured" strategy was employed, the patient was allowed to digress; and when the "alternating" strategy was used, the experimenter maintained a structured framework while still allowing the patient to make a few digressions. Each frontal-lobe subject was assigned a conversational strategy order (by random drawing) and each strategy was randomly assigned one of three interview topics: movies, music, or television. This was designed to eliminate any effects brought about by a given topic-strategy combination. The control subjects performed the same set of tasks, under the same conditions, as the matched frontal-lobe damaged subjects. Description of the three conversational strategies Structured strategy (S1). The experimenter interviewed the subject on one of the three topics. Whenever the subject digressed, the experimenter systematically came back to the initial topic. Example: Interview about movies Experimenter: Do you like funny movies? Subject: Yeah, because if you go to the movies to see misery, its no use. It's no use because misery is everywhere -- just look at -Experimenter: And what other kinds of movies do you like? (return to topic) Unstructured strategy (S2). The experimenter interviewed the subject on one of the three topics. Whenever the subject digressed, she pursued the topic the subject had brought up. Example: Interview about music Experimenter: So you like rock? Subject: I went to a concert last week -- the tickets are too expensive! Experimenter: Is it really expensive? (continuation of subject's topic) 10 Alternating strategy (S3). The experimenter interviewed the subject on one of the three topics. She allowed the subject to digress periodically by alternating between strategies S1 and S2. Example: Interview about movies Experimenter: What kind of movies do you like? Subject: Stuff like Vandamme, you know! Subject: Karate, I mean, combat sports, is what I really like. Experimenter: Combat sports? (continuation, unstructured strategy (S2)) Subject: Karate, boxing and things like that / I used to do those, it's great. Experimenter: And what about movies? (Return to initial topic, structured strategy (S1)) In all three strategies, if the subject did not digress, the experimenter asked him/her to give more details about the topic. Before the data collection began, the experimenter was trained until she was able to consistently follow the rules for each of the three strategies. The training consisted of recording interviews with persons who were not selected for the experimental sample and then examining the "errors" made with the help of a trained individual who knew the rules perfectly. Transcribing and pragmatic index coding Each subject (experimental or control) was interviewed individually three times within the three-week period. A tape recorder was used to avoid cumbersome note taking by the experimenter and to ensure high-quality transcription. There was no time limit to the interviews and their duration varied across subjects. However, only the first twelve minutes of the conversation were transcribed. For the first two minutes, the communication situation was still getting established, so only the next ten minutes were coded and analysed. Coding of speaking turns and utterances (measures of speech quantity). The interviews were transcribed and segmented into speaking turns and utterances in accordance with the dialogue segmentation criteria previously used by Bernicot, Comeau and Feider (1994). A speaking turn ended whenever one or both of the following events occurred: a change of speaker, or a pause of more than two seconds (Sacks, Schegloff & Jefferson, 1974). In a speaking turn, the utterances are delineated by terminal juncture or paraverbal behaviours (such as laughter). Terminal juncture was identified by the following phonetic characteristics (Halliday, 1975): (a) a terminal contour (falling, rising-falling) and (b) a steady intonation pattern followed by vocal arrest (300 ms). Coding the digression index (measure of ability to keep to the interview topic). Digressions were defined here as cases where the subject brought up a topic other than the one initially proposed by the experimenter (television, movies, or music). Digression and non-contingency differed in that a subject could exhibit non-contingency (by not responding to the demands of 11 others) without digressing (by staying on the topic of the interview). Digressions were counted by tallying the number of speaking turns where a new digression theme was brought up (a digression theme could last several speaking turns). The term theme is used here to refer to a topic of conversation chosen unilaterally by one of the interlocutors. The percentage of speaking turns where the subject made such digressions was then calculated. Coding the contingency index (measure of interview topic development). Unlike HoffGinsberg (1994), we used this index to assess contingency across speaking turns rather than across utterances. In the light of the data collected here, it appeared more appropriate to consider the speaking-turn level of analysis, which we felt gave a better overall picture of the interviews. The results presented pertain to within-subject contingent speaking turns without an intervening remark by the experimenter (WSC). These were characterised by the fact that the subject continued to talk about the topic he/she had introduced in his/her own last speaking turn, without experimenter intervention. Only those speaking turns that pertained to the topic of the interview were taken into account. Example: interview about television Subject: Do I like television -Subject: Often during vacation there are some beautiful stories on channel 6 and I often watch channel 6 during vacation. The interviews of two subjects (i.e., six interviews or 9% of the corpus) were coded by two separate coders. The inter-coder agreement rate was .84 (number of speaking turns coded in the same way, divided by the total number of speaking turns). Experimental hypotheses Given our main goals and assumptions, our data collection procedure, the rules governing the interview format, and the indexes chosen, the following experimental hypotheses were set forth. 1. Speech quantity: An interviewee is supposed to speak for long stretches, so the number of utterances per speaking turn should be higher for control subjects than for experimental subjects. 2. Keeping within the interview topic: An interviewee is supposed to stick to the topic defined by the interviewer and avoid digressions, so the percentage of speaking turns where the subject digresses should be greater for experimental subjects than for control subjects. 3. Development of the interview topic: An interviewee is supposed to expand upon the topic defined by the interviewer, so the number of within-subject contingent speaking turns without an intervening remark by the experimenter (WSC) should be greater for control subjects than for experimental subjects. 12 4. Variations as a function of the experimenter's strategy: The values obtained for the experimental subjects on the three indexes mentioned above should vary with the conversational strategy used by the experimenter. Results Only the results related to our experimental hypotheses are presented below. For each index (speech quantity, digression, and contingency), the results of the two groups are compared, and variations as a function of the conversational strategy are analyzed. The contingency and digression indexes were expressed as percentages so the data would not be skewed by differences in the total number of speaking turns made during each interview. Speech quantity indexes Figures 1 and 2 give the number of speaking turns and the number of utterances per speaking turn made by the subjects and by the experimenter in the two groups, for each of the three conversational strategies. The results were processed for each index using a three-way ANOVA with a Group (2: Experimental/Control) by Speaker (2: Subjects/Experimenter) by Strategy (3: Structured/Unstructured/Alternating) design. Any observed differences were taken to be significant at the .05 level. As a whole, for the number of speaking turns (Figure 1), the Group effect (F(1, 32) = 168.30; p < .0001) and the Speaker effect (F(1, 32) = 8.90; p < .005) were significant: speaking turns in the experimental group interviews outnumbered those in the control group (for both types of speakers), and there were more turns for the subjects than for the experimenter. In addition, the Strategy effect (F(1, 32) = 8.90; p < .005) and the Group-by-Strategy interaction (F(2, 64) = 8.58; p < .0004) were also significant: the difference between the strategies was much greater in the experimental group than in the control group. Partial comparisons showed that this difference was nonsignificant in the control group but significant in the experimental group (F(2, 34) = 7.59; p < .002). For the experimental subjects, there were more speaking turns with the alternating strategy (F(1, 17) = 16.47; p < .001) and with the unstructured strategy (F(1, 17) = 4.90; p < .04) than with the structured strategy. Concerning the number of utterances per speaking turn (Figure 2), the overall Group (F(1, 32) = 25.18; p < .0001) and Speaker (F(1, 32) = 71.40; p < .0001) effects were significant, as was the Group-by-Speaker interaction (F(1, 32) = 26.07; p < .0001). The difference between the experimenter and the subjects (with the latter speaking more than the former) was much more pronounced in the control group (1 vs. 9) than in the experimental group (1 vs. 3). There was no Strategy effect. 13 Partial comparisons showed that while this difference was significant both in the control group (F(1, 16) = 55.49; p < .0001) and in the experimental group (F(1, 16) = 16.24; p < .001), the F-value and the significance level were higher for controls. The Group-bySpeaker interaction also pointed out a significant difference between the control and experimental groups, both for the subjects (favoring the control group: F(1, 16) = 25.63; p < .001) and for the experimenter (but favoring the experimental group: F(1, 16) = 9.73; p < .01). Insert Figure 1 and Figure 2 about here Digression index Figure 3 plots the percentage of digressions (ratio of the number of speaking turns containing a digression to the total number of speaking turns) in the two subject groups, for each of the three conversational strategies. The results were processed using a two-way ANOVA with a Group (2: Experimental/Control) by Strategy (3: Structured/Unstructured/Alternating) design. Any observed differences were taken to be significant at the .05 level. The group effect was significant (F(1, 16) = 31.77; p < .0001): experimental subjects made more digressions (about 10%) than controls (about 2%). The effects of the Strategy variable (F(2, 32) = 11.14; p < .0002) and of the Group-by-Strategy interaction (F(2, 32) = 11.51; p < .0001) were also significant. The strategy had more effect for the experimental group than for the control group. Moreover, the effect was not the same for the two groups. Partial comparisons showed, for the experimental group, that the Strategy effect was significant (F(2, 16) = 12.44; p < .0005) and that the digression rate was higher with the unstructured strategy than with the alternating strategy (F(1, 8) = 9.87; p < .01), and higher with the alternating strategy than with the structured strategy (F(1, 8) = 10.92; p < .01). For the control group, the Strategy effect was less strong but nevertheless significant (F(2, 16) = 3.86; p < .04): there were more digressions with the alternating strategy than with the structured strategy (F(1, 8) = 6.62; p < .03). Insert Figure 3 about here We felt it would be worthwhile to conduct a qualitative analysis of the themes of digression. Table 3 and 4 lists the main digression themes found for the experimental and control groups. For experimental subjects (see Table 2), certain themes were brought up in a large number of interviews. For example, antiestablishment remarks, and statements about changes due to the accident, were made in seven interviews. Based on this analysis, we can conclude that there are certain themes that preoccupy subjects with frontal lobe damage and make their way into their discourse in a recurring fashion. In addition, the same digression theme was often found repeatedly in the interviews of a given subject. For example, subject 5 made antiestablishment 14 remarks during all three interviews. Our analysis also showed that the digressions of frontal patients were often nonsensical and appeared at illogical points in the conversation due to the inappropriate association of ideas. Their digression themes were far removed from the interview topic. Example: Digression of an experimental subject during the interview about music Subject: The tune, he sings it too and it's beautiful, and then there's this thing I tell myself, that seeing the way I think, I could be from the hippie generation! No kidding! Because, you see, me right now I'm not okay -When the control subjects made digressions (see Table 3), they were followed by a selfinitiated return to the interview topic without experimenter prompting. Also, the control subjects' digression themes were never very far from the interview topic. Example: Digression of a control subject during the interview about television Subject: Glamour songs are okay for a while, but I really prefer it when things move because I'm the dynamic type and songs resemble me. I like those styles because they resemble me. Subject: I know that at my aunt's funeral -- I'm getting off track but I'll come back to it -- they were playing all the songs she used to like. Songs that were with her throughout her life and that were like her. Note also that the control subjects digressed at most once within a given interview, and that, unlike the experimental group, there were no recurring digression themes within or across subjects. Insert Table 2 and 3 about here Contingency index Figure 4 plots the percentage of within-subject contingent speaking turns with no intervening experimenter remark (WSC) for each group of subjects and each conversational strategy. The results were processed for each index using a two-way ANOVA with a Group (2: Experimental/Control) by Strategy (3: Structured/Unstructured/Alternating) design. Any observed differences were taken to be significant at the .05 level. The overall analysis yielded a significant effect of the Group variable (F(1, 16) = 19.36; p < .0004): control subjects produced more speaking turns of this type than did experimental subjects. Although the Strategy effect and the Group-by-Strategy interaction were nonsignificant, partial comparisons pointed out an interesting tendency: the difference between the control and experimental subjects was significant (with the latter ahead of the former) for the 15 structured (F(1, 16) = 10.01; p < .006) and unstructured (F(1, 16) = 19.87; p < .0003) strategies, but not for the alternating strategy. Insert Figure 4 about here Discussion Do patients with frontal lobe damage have trouble abiding by the rules of a particular type of conversation such as an interview? In the present situation where the patients were in the interviewee position, did their conversational behaviour depend on the interviewer's strategy? The data we obtained allow us to answer affirmatively to these two questions and thereby validate our hypotheses. The fact that the experimenter's behaviour (in terms of number of utterances per speaking turn) did not vary with the conversational strategy she used further proves the validity of our results. Our first hypothesis concerned speech quantity. An interviewee is supposed to speak for long stretches, so the number of utterances per speaking turn should be higher for control subjects than for patients. This hypothesis was validated: the normal subjects took speaking turns made up of nine utterances, whereas the turns of the frontal-lobe damaged subjects only contained three. Thus, the frontal patients had difficulty fulfilling the interviewee's role by holding the floor to expand upon the topic the interviewer proposed. The results for the number of speaking turns in the two groups tells us a little more about the patients' difficulty. The subjects with frontal lobe damage produced more speaking turns than the normal subjects. Moreover, for both indexes (speaking turns and utterances per speaking turn), the experimenter always talked more with the frontal lobe subjects than with the normal subjects. It thus seems that patients with frontal lobe damage differ from normal subjects in utterance grouping and distribution: they need substantial prompting by the interviewer. These findings are compatible with the results obtained in the studies by Mentis and Prutting (1987), where patients with brain damage exhibited reduced speech spontaneity and had slow ideation, and by Coelho, Liles and Duffy (1991), where evidence of reduced production was found in these subjects. Our second hypothesis dealt with the ability to keep to the interview topic. An interviewee is supposed to talk solely about the topic set by the interviewer: he/she should not digress too much. The percentage of speaking turns with interviewee digressions was greater for the experimental subjects than for the controls. The data we obtained thus validate our hypothesis and supply some additional information. First of all, patients with frontal lobe damage appear to have trouble following the rules of interviews: an interviewee must stay on the subject matter proposed by the interviewer. If we consider the constraints of the interview situation, we can regard digressions as a breach of the communication contract. However, the initial rules in the contract can be negotiated and certain digressions can be tolerated, provided they 16 are rare and the subject comes back to the initial topic on his/her own. On this matter, it is interesting to note that when the normal subjects digressed, they came back to the initial interview topic without prompting, something the frontal lobe subjects did not do. Secondly, our qualitative analysis indicated that the nature of the digressions was not the same in the two groups: the frontal lesioned subjects' digression themes were recurring and unrelated to the interview topic. In contrast, the normal subjects' digressions were not recurring and they pertained to subject matters that had some connection with the interview topic. These results are consistent with those obtained by Mentis and Prutting (1991) and by Bond and Godfrey (1997). These authors showed that frontal patients have difficulty taking others into account and remain focused on their own ideas; they also noted that the topic changes of these subjects during a conversation are often inappropriate. Our results are consistent with the Marsh and Knight (1991) study too, where the patients exhibited several conversational disorders such as inattentiveness towards the interlocutor. Our third hypothesis had to do with the development of the interview topic by the interviewee. An interviewee must expand upon the topic defined by the interviewer, so the number of within-subject contingent speaking turns without an intervening remark by the experimenter should be greater for control subjects than for patients. This hypothesis was also validated. The normal subjects mainly produced speaking turns without an intervening remark, which means that, unlike the subjects with frontal lobe damage, they were capable of holding the floor for several minutes without experimenter intervention. Our results thus suggest that frontal-damaged patients have trouble constructing an appropriate response and often need to be prompted by their interlocutors. Thus, in support of our first three hypotheses, it appears clear here that subjects with frontal lobe damage have trouble abiding by the rules of the interview situation in three different ways: speech quantity, staying on the interview topic, and development of that topic. Our fourth hypothesis concerned potential variations that hinge on the experimenter's conversational strategy: for the three pragmatic indexes used in this study (speech quantity, digression, and contingency), the experimental subjects' conversational behaviour was expected to vary as a function of the strategy implemented by the interviewer. Our results confirmed this hypothesis. Certain interviewing strategies appear to bring the performance of patients with frontal lobe damage closer to that of normal subjects. It was when the experimenter used an unstructured strategy or an alternating strategy that the frontal lobe subjects produced the greatest number of utterances per speaking turn. The structured strategy helped keep the patients on track. The alternating strategy enabled them to take more speaking turns without experimenter prompting. Thus, the frontal subjects' discourse was indeed dependent upon the conversational strategy adopted by the experimenter. As a whole, our data is in line with the findings obtained by Peter (1995, 1999), who showed that the impact of the conversational strategy is great. Our data reinforce Peter's (1995, 1999) results, 17 insofar as the interview strategy variations we found were systematic and the analysis pertained to nine patients (not just one). The three conversational strategies used here by the experimenter gave the patients the opportunity to exercise different pragmatic skills, and to come closer the performance of normal subjects. Note that the structured strategy (currently the most common rehabilitation technique) was not always the one that helped patients converse more like normal individuals. For example, the unstructured strategy or the alternating strategy enabled the frontal lobe patients to express themselves the most (number of speaking turns). This result is all the more interesting in that previous studies (Mentis & Prutting, 1987; Coelho, Liles & Duffy, 1991) have shown that these patients do not often express themselves spontaneously: this strategy may therefore give them the chance to realize a potential that exists but which is not expressed in the situations usually proposed to them. The findings for the contingency index and the alternating strategy are also quite interesting: they show that the alternating strategy can teach subjects with frontal lobe damage certain interview principles, in addition to helping them improve the structure of their responses. We saw that the number of speaking turns without an intervening remark, which were characteristic of normal subjects, increased in the subjects with frontal lobe damage when the experimenter used the alternating strategy. Although their performance did not reach the level of the controls, this finding is consistent with the idea that the alternating strategy helps brain-damaged patients adapt to the conversational format of interviews. These last conclusions suggest that in therapy programs for subjects with frontal lobe damage, constraints imposed by others (to optimise performance) often favour passiveness and do not truly enhance the patient's potential to learn. The alternating conversational strategy thus appears to be the most advantageous for these subjects, not only during an actual exchange but also in the long run, for it promotes the learning of the cooperative principles that underlie any satisfactory conversation. Relating our conclusions to Bruner's (1983, 1990) theories on child learning of interaction formats, we can contend that only the alternating strategy offers the potential for regulating the interaction. In this respect, this strategy not only permits true negotiation of the principles of the interview format (unlike a structured framework which merely imposes the rules of the communication contract) but also promotes the learning of that format. This study showed once again that the creation of experimental paradigms can open up new pathways for understanding and assessing frontal-lobe disorders (Linscott, Knight & Godfrey, 1996; Mayes & Dauym, 1997). Our results demonstrate in a precise way that patients with frontal lobe damage have trouble abiding by interview rules about speech quantity and keeping with and development of the interview topic. In addition, our data contribute to the body of findings on aphasic patients (Kagan, 1999; Kagan & Gailey, 1993; Laasko & Klippi, 1999) by clearly demonstrating that the verbal productions of these patients vary with their interlocutor's strategy, and by showing how these variations could be put to fruitful use in therapeutic techniques. 18 Hence, at the close of this study, it appears worthwhile to conduct further research that relates the results obtained on pragmatic tasks with the performance observed on certain neuropsychological tests. Such a two-level analysis should contribute to improving our understanding of the cognitive processes at play in the communication deficits of subjects with frontal lobe damage (topic management, building an argumentation, digressions, etc.). This multimodal approach should also provide the opportunity for developing new therapy techniques for brain-damaged patients. 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Topics in Language Disorders, 9, 34-39. 22 Table 1 - Characteristics of experimental group (subjects with frontal lobe damage) and control group (normal subjects) EXPERIMENTAL GROUP Subjects with frontal lobe damage 1 2 3 4 5 6 Sex Age IQ M F M M M M 19;8 15;3 18;11 20;7 18;7 16;1 90 93 89 75 79 90 7 F 24;1 97 8 9 M F 20;6 19;8 89 74 years;months Time since accident years;months CONTROL GROUP Normal subjects 1 2 3 4 5 6 7 8 9 Frontal injury location Sex Age years;months M M M M M M F M F 19;6 15;1 18;12 20;6 18;9 16;2 24;1 20;6 19;7 Right Bilateral Bilateral Bilateral Temporal left Temporal right and tempoparietal left Temporal left and temporal right Bilateral Temporal right 3;10 3;0 12.6 6;0 4;0 6;7 8;3 4;6 6;5 23 SUBJECTS 60 Nb 50 40 30 20 10 0 Together Structured Unstructured Experimental subjects Alternating Control subjects EXPERIMENTER 50 Nb 40 30 20 10 0 Together Structured Unstructured Experimental subjects Alternating Control subjects Figure 1 - Mean number (Nb) of subject and experimenter speaking turns and standard deviation by group, for the three conversational strategies taken together and separately. 24 SUBJECTS 16 14 12 10 8 6 4 2 0 Nb Together Structured Unstructured Experimental subjects Alternating Control subjects EXPERIMENTER 1,2 Nb 1 0,8 0,6 0,4 0,2 0 Together Structured Unstructured Experimental subjects Alternating Control subjects Figure 2 - Mean number (Nb) of subject and experimenter utterances per speaking turn and standard deviation by group, for the three conversational strategies taken together and separately. 25 30 % 25 20 15 10 5 0 Together Structured Unstructured Experimental subjects Alternating Control subjects Figure 3 - Mean percentage (%) of digressions and standard deviation by group, for the three conversational strategies taken together and separately. 26 Table 2 - Main digression themes of the experimental subjects for each of the three conversational strategies (the number of times a theme was brought up during the interview is shown in parentheses). Subject Structured strategy Unstructured strategy Alternating strategy 1 Police state(1) Handicaps (2) Man’s destructiveness(6) Man’s destructiveness(2) The accident(1) Sadness(2) Animals(4) Music(3) Police state(5) Animals(2) 2 3 Sadness(3) Friends(2) Friends(1) Going out(4) Handicaps(2) TV movies(3) Health(1) Going out(4) Enemies(2) Friends(1) The accident(2) Music (4) Boxing(3) Leisure activities(3) Bowling(2) Horses(4) Antiestablishment(2) 4 Antiestablishment(3) Antiestablishment(3) Sadness(4) Animals(6) The accident(4) Handicaps(5) Cost of living(4) 5 6 Antiestablishment(2) Antiestablishment(4) Being poor(2) Sadness(4) Leisure activities(5) Vacation(8) Telling movie plots(4) Family(3) Accident-related changes(2) Leisure activities(3) Handicaps(6) Accident-related Battered women(3) changes(7) The future(3) Motherhood(2) Childhood(1) Antiestablishment (3) Jokes(4) Accident-related How the school is run (5) changes(5) Friends(3) Personal problems(1) Personal problems(3) 7 8 9 Jokes (6) The accident (2) Personal problems(2) Antiestablishment(5) 27 Table 3 - Main digression themes of the control subjects for each of the three conversational strategies (the number of times a theme was brought up during the interview is shown in parentheses). Subject Structured strategy 1 Funeral(1) 2 Mother(1) Unstructured strategy Alternating strategy Music(1) 3 4 5 Le Pen(1) (French politician) Video games(1) 6 7 8 Brother(1) 9 Going out(1) 28 50 45 40 35 30 25 20 15 10 5 0 % Together Structured Unstructured Experimental subjects Alternating Control subjects Figure 4 - Mean percentage (%) of within-subject contingent speaking turns with no intervening experimenter remark, and standard deviation, by group, for the three conversational strategies taken together and separately.