Face-to-Face Communication in Aphasia: The Influence of Conversation Partner Familiarity on a Collaborative Communication Task

Doedens, Willemijn; Bose, Arpita; Lambert, Lydia; Meteyard, Lotte

doi:10.3389/fcomm.2021.574051

ORIGINAL RESEARCH article

Front. Commun., 08 June 2021

Sec. Psychology of Language

Volume 6 - 2021 | https://doi.org/10.3389/fcomm.2021.574051

This article is part of the Research Topic Socially Situated? Effects of Social and Cultural Context on Language Processing and Learning View all 16 articles

Face-to-Face Communication in Aphasia: The Influence of Conversation Partner Familiarity on a Collaborative Communication Task

Willemijn Doedens*

Arpita Bose

Lydia Lambert

Lotte Meteyard

ABCD Lab, School of Psychology and Clinical Language Sciences, University of Reading, Reading, United Kingdom

Aphasia is language impairment due to acquired brain damage. It affects people’s ability to communicate effectively in everyday life. Little is known about the influence of environmental factors on everyday communication for people with aphasia (PWA). It is generally assumed that for PWA speaking to a familiar person (i.e. with shared experiences and knowledge) is easier than speaking to a stranger (Howard, Swinburn, and Porter). This assumption is in line with existing psycholinguistic theories of common ground (Clark, 1996), but there is little empirical data to support this assumption. The current study investigated whether PWA benefit from conversation partner (CP) familiarity during goal-directed communication, and how this effect compared to a group of neurologically healthy controls (NHC). Sixteen PWA with mild to severe aphasia, sixteen matched NHC, plus self-selected familiar CPs participated. Pairs were videotaped while completing a collaborative communication task. Pairs faced identical Playmobile rooms: the view of the other’s room was blocked. Listeners attempted to replicate the 5-item set-up in the instructor’s room. Roles were swapped for each trial. For the unfamiliar condition, participants were paired with another participant’s CP (PWA were matched with another PWA’s CP based on their aphasia profile). The outcomes were canonical measures of communicative efficiency (i.e. accuracy, time to complete, etc.). Results showed different effects in response to the unfamiliar partner for PWA compared to NHC: In the instructor role, PWA showed faster trial times with the unfamiliar partner, but similar accuracy scores in both conditions. NHC, on the other hand, showed similar trial times across CPs, but higher accuracy scores with the unfamiliar partner. In the listener role, PWA showed a pattern more similar to NHC: equal trial times across conditions, and an improvement in accuracy scores with the unfamiliar partner. Results show that conversation partner familiarity significantly affected communication for PWA dyads on a familiar task, but not for NHC. This research highlights the importance of identifying factors that influence communication for PWA and understanding how this effect varies across aphasia profiles. This knowledge will ultimately inform our assessment and intervention of real-world communication.

Introduction

One-third of individuals who suffer a stroke will experience aphasia (difficulties speaking and understanding language, reading and writing) (Spaccavento et al., 2013), with detrimental effects on communication and functioning in everyday life (Lam and Wodchis, 2010; Hachioui et al., 2014). When compared against various health conditions (e.g. cancer and Alzheimer’s disease) aphasia has the highest impact on quality of life (Hilari et al., 2003; Lam and Wodchis, 2010; Spaccavento et al., 2013). The loss of functional language use affects social, vocational, and emotional well-being (Hilari et al., 2003; Spaccavento et al., 2013), preventing People with Aphasia (PWA) from participating in society and maintaining relationships.

Traditionally, the study of aphasia has focused on impairments of language, with assessment tasks that present isolated language elements (e.g. sounds, words, sentences) in highly controlled lab environments. These studies have been the foundation for the development of reliable assessment instruments and intervention plans targeted at particular profiles of language impairment (Thompson et al., 2008). However, it is generally accepted that such impairment-based performance measures do not reliably predict communication ability in the real world (Holland, 1982; Kolk and Heeschen, 1992; Wilkinson, 1995; Beeke et al., 2007; Davidson et al., 2008; Armstrong et al., 2011). Perhaps because of the complexity of language and communication, the same level of detailed analysis has not been applied to real-world communication for PWA (Leaman and Edmonds, 2019). Providing reliable assessment and evidence-based interventions at the level of communication has, for that reason, remained problematic in aphasiology (Brady et al., 2016). This is a crucial gap in knowledge, as improvement in the ability to communicate in one’s own day-to-day environment remains one of the most important long-term goals reported by clinicians and PWA themselves (Thompson et al., 2008).

There is a need for systematic, theoretically driven research on naturalistic communication in aphasia. Recently, we showed how a theoretical framework of situated language use, borrowed from research with neurologically healthy controls (NHC) (Clark, 1996), can be applied to aphasia rehabilitation (Doedens and Meteyard, 2019). It provides a structure along which different components of real-world communication, and their influence on a person’s ability to communicate, can be examined systematically. The framework defines communication as being 1) interactive–including atleast one other person, 2) multimodal–involving multiple channels of information and 3) contextual–grounded in shared situational, personal and social knowledge.

Here, we will focus on the contextual aspect of communication. One part of contextual information is common ground shared with a conversation partner (CP) – part of which is modulated by the familiarity of that CP. For PWA, questionnaires on communication often distinguish between the ability to communicate with familiar and unfamiliar CPs (e.g. the disability questionnaire of the Comprehensive Aphasia Test; Howard et al., 2004; or the Aphasia Impact Questionnaire-21; Swinburn et al., 2018). The assumption is often made that it is easier for PWA to speak to a familiar person than speaking to a stranger (Green, 1982; Wirz et al., 1990; Ferguson, 1994; Perkins, 1995; Howe et al., 2008; Laakso and Godt, 2016). The familiarity advantage has also been reported by PWA as an influential factor when it comes to ease of communicating (Dalemans et al., 2010).

Conversation Partner Familiarity in the Control Literature

Conversation partner familiarity is more specifically defined as personal common ground (Clark, 1996). This constitutes a set of past experiences, beliefs and knowledge that are shared between two people. There is a belief that people who know each other well understand each other better (i.e. communication is more accurate) and need fewer words to understand each other (i.e. communication is more efficient) than when strangers communicate (Sillars et al., 1997; Pollmann and Krahmer, 2017). Part of the assumption is that when people know each other well, they are better at taking the other person’s perspective (Mead, 1934; Fussell and Krauss, 1989). In line with this, a number of studies have shown that people that are familiar with each other (e.g. friends, couples), feel like they understand and know each other well (Pollmann and Finkenauer, 2009) and overestimate the degree to which they will be understood by their familiar partner (Dixon et al., 1998; Savitsky et al., 2011; Riordan and Trichtinger, 2016). Research with NHC has shown that the presence of shared experiences and knowledge, personal common ground, can facilitate communication (Clark, 1996; Brown-Schmidt, 2009a). In conversation, interlocutors can rely on this shared information as being “given”, i.e. not requiring too much further explanation. As a result, CPs can rely on more informal, implicit, abbreviated language in their exchanges (Herrmann, 1983; Hornstein, 1985; Clark, 1996). By relying on the “givenness” of shared information, speakers can produce less complete utterances (Bard et al., 2014), while listeners can use personal common ground to restrict the number of possible interpretations based on the shared knowledge (Brown-Schmidt, 2009b; Skipper, 2014). It has, therefore, been suggested that reliance on shared knowledge can make communication less effortful and more efficient (i.e. requiring less time, fewer words and/or less cognitive energy, Boyle et al., 1994; Clark, 1996; Horton and Gerrig, 2005; Smith et al., 2005; Zwaan, 2016). In line with this, Isaacs and Clark (1987) showed that New Yorkers were more efficient in describing buildings in the city when they spoke to other New Yorkers compared to non-New Yorkers. In a study by Pollmann and Krahmer (2017), familiar and unfamiliar pairs did not differ on communicative efficiency, as measured in number of words and minutes spent on the task. The familiar pairs did show an advantage in accuracy scores, but this was dependent on the task: accuracy scores on a game of Taboo via email (with no non-verbal communication or feedback in the form of clarification questions) did not differ between the two groups. In a face-to-face setting, familiar pairs achieved higher scores than unfamiliar pairs. Brown-Schmidt (2009a) found a similar effect of task: only performance on an interactive task showed an influence of common ground between conversation partners (participants were manipulated on shared knowledge within the experiment, not on personal familiarity; Brown-Schmidt, 2009b). The authors argued that the type of task and its complexity might have been of influence: the more complex, the greater the need to rely on shared information to complete the task. Interestingly, Pollmann and Krahmer (2017) showed that in addition to the higher accuracy scores, familiar pairs reported higher levels of motivation and enjoyment of the game, suggesting that these factors might influence communicative efficiency and accuracy as well. Finally, on the non-interactive email task, an effect of friendship closeness on accuracy was found for the group of familiar pairs. Andersson and Ronnberg (1997) showed that participants performed better on a word association task when working with friends compared to strangers. Fussell and Krauss (1989) also reported higher levels of accuracy when subjects were asked to interpret a message that was recorded specifically for them by a friend, than when they were asked to interpret a message that was recorded by a stranger. While the difference in accuracy scores between these conditions was significant, it was very small. The authors hypothesized that the traditional referential communication task might not have required participants to rely on personal common ground. Instead, reliance on general, community-wide knowledge would have enabled participants to successfully interpret messages recorded by a stranger (Fussell and Krauss, 1989). Furthermore, the authors suggested that the degree to which familiar pairs know each other (i.e. length of time, level of intimacy) might have mediated this effect, as the familiar pairs in their study had known each other for less than six months (Clark and Schaefer, 1987; Fussell and Krauss, 1989).

The research on the benefit of conversation partner familiarity is, however, inconclusive. Gould et al. (2002) did not find differences across tasks between familiar and unfamiliar pairs. The authors also suggested that the familiarity effect might only be present in particular communicative or experimental contexts, as well as depend on the type of relationship that is studied. Schober and Carstensen (2010) also found no difference between familiar and unfamiliar pairs on their efficiency and accuracy in describing unfamiliar things, such as tangram shapes. While Pollmann and Krahmer (2017) found differences in accuracy between familiar and unfamiliar pairs on a face-to-face task, no differences were found between the groups on efficiency. Finally, it has also been suggested that the existence of shared knowledge between two interlocutors might not necessarily lead to a reliance on that shared knowledge per se. Instead, it might lead the speaker to rely more on their own knowledge. While this can facilitate communication on some topics (when speaking about topics that are part of shared knowledge), it can also lead to greater confusion when communicating about topics that are not part of common ground (Wu and Keysar, 2007; Savitsky et al., 2011). Overall, the research on the effect of conversation partner familiarity on communication efficiency and accuracy remains relatively inconclusive. It is suggested to depend on factors such as the type and complexity of task, the topic of conversation and whether it requires personally shared knowledge to be understood, the type, length and intimacy of the relationship under study and the motivation of the interlocutors on the task.

Conversation Partner Familiarity in the Aphasia Literature

Only a small number of studies have explored the influence of personal common ground on communication for PWA. Leaman and Edmonds (2019) analyzed and compared the unstructured conversations of eight PWA (most with mild anomic aphasia) with a familiar conversation partner (FCP) and an unfamiliar speech and language therapist (SLT). The authors reported no differences on measures of communicative success, on linguistic measures such as grammaticality (morphological and verb tense/mood errors) and sentence production (correct use of a complete sentence frame and the relevance of lexical items in the frame in the discourse context), or on lexical retrieval behaviors (false starts, repetitions, pauses of 2+ s, etc.). These findings suggest that some linguistic characteristics of conversation for PWA might remain stable across conversation partners.

Kistner (2017) assessed gesture use by twenty PWA (ranging from severe to mild aphasia) and NHC in conversation with FCPs and unfamiliar conversation partners (UFCP). A procedural and a narrative conversational task were used to elicit conversation. UFCPs were SLT students or researchers with knowledge of aphasia. In this study, both PWA and NHC showed an increase in the number of gestures when speaking to the UFCP as compared to the FCP. The authors hypothesized that gesture production increased to help disambiguate meaning or as speech became more complex. With the UFCP, this need increased due to the lack of shared reference. Williams et al. (1994) explored the influence of conversation topic and conversation partner familiarity for 22 PWA and ten NHC on a procedural and story-retell task. The syntactic complexity measures in the study showed no effect of CP familiarity (Williams et al., 1994). On the same dataset, Li et al. (1995) found no significant differences on discourse grammar between conversations with FCPs and UFCPs, except on the description of the setting in the story retell task, where PWA provided more detail with the FCP. The authors suggested PWA might have felt more comfortable or at ease with the familiar CP, which could have facilitated recall of that particular aspect of the story. Finally, case studies by Gurland et al. (1982) and Lubinski et al. (1980) showed that PWA used different communication styles depending on the familiarity of their CP: Gurland et al. (1982) showed a greater number of acknowledgments were produced in conversation with a familiar CP, while with the unfamiliar CP, topic-relevant turns increased. The authors suggested PWA might take on a more “passive, less informative role with the spouse (familiar CP) vs. the clinician (unfamiliar CP)” (Williams et al., 1994). Lubinski et al. (1980) compared the unstructured conversation of one PWA with a familiar (spouse) and a therapy session with an UFCP (in this case, a SLT). The topic of conversation was not controlled for. The number of conversational breakdowns and repairs were assessed: similar types of conversational breakdowns were found with the FCP and UFCP. The way in which the breakdowns were repaired, however, differed significantly. UFCPs (SLT) tended to gloss over the breakdowns, while FCPs (spouse) actively attempted to repair them collaboratively with the PWA. The authors suggested that one reason for this difference was the different goals each CP had during their conversation with the PWA: the clinician often let the PWA repair the conversational trouble, while the spouse wanted to–collaboratively–discuss the plans for that day. Ferguson (1994) found no difference in trouble indicating behaviors between FCP and UFCP in a study with eight PWA, where the conversational topic was slightly more aligned. The authors found that the way these troubles were dealt with was different depending on the familiarity of the CP: UFCP more often took on the responsibility of repairing the trouble (i.e. “other-repair”), rather than letting the PWA repair the trouble (i.e. “self-repair”). The authors hypothesized that by not letting PWA repair the trouble as often, UFCPs might have been driven by a desire to avoid potential continued conversational breakdown. The familiarity manipulation might not have been sufficient in this latter study: the role of UFCP was filled by someone who knew the PWA less well compared to the FCP, but still had known the PWA for years.

Confounding Factors in Interactive Communication in Aphasia

In addition to the effect of personal common ground, there are two confounding factors that have been shown to influence the communicative ability of PWA. First, research has shown that communication for PWA is influenced by the extent of knowledge the CP has about aphasia, the language impairment and on potential communication strategies they can use to facilitate communication (Rayner and Marshall, 2003). CPs with knowledge of communicating with PWA have been shown to enable PWA to communicate more effectively and increase the PWA’s level of participation in conversation (Lindsay and Wilkinson, 1999; Pound et al., 2000; Kagan et al., 2001; Simmons-Mackie et al., 2010; Wilkinson and Wielaert, 2012; Nykanen et al., 2013). PWA also specifically self-report the positive impact of communicating with someone who knows about aphasia and what communication strategies to use during conversation (Dalemans et al., 2010; Harmon, 2020).

Second, the sense of comfort and support experienced during communication has been suggested as an important factor for communicative ability (Dalemans et al., 2010; Worrall et al., 2010; Harmon, 2020). Though not exclusively, this sense of comfort and support is often associated with the familiarity of the CP. This line of reasoning suggests that the fear of not being able to express oneself due to the language impairment and subsequently the fear of “losing face” or of being perceived unfavourably because of the communication difficulties, can make communication with an UFCP more effortful and a more negative experience (Harmon, 2020). For PWA, this could potentially result in more errors in their language production, more and longer word searches, or potentially result in avoidance of the interaction with the UFCP resulting in, for example, shorter interactions altogether. Suggestions to this end have been made in the literature (Li et al., 1995; Kistner, 2017). In a discussion of the use of compensatory communication strategies by PWA, Simmons-Mackie and Damico showed that PWA may vary their communication strategies depending on the goal in a particular context, such as “looking okay”, rather than being maximally communicatively effective (Simmons-Mackie and Damico, 1995). To the knowledge of the authors the sense of being at ease during communication and the influence of conversation partner familiarity has not been explored empirically.

In sum, the existing research suggests that the presence of personal common ground can influence communication for PWA. The existing evidence base is small, but it seems that the effect of conversation partner familiarity might depend on the level at which communication is measured. It seems that lower level linguistic measures such as verb or sentence production could remain stable across different conversation partners, while higher level communication strategies such as the use of gesture or the repair of conversational trouble might vary. More work is needed, however, to assess whether this advantage exists, how it manifests, whether it exists for all types of aphasia, and if it is mediated by other factors such as aphasia severity. It is crucial to control for the influence of other confounding factors such as knowledge of aphasia of the CP, the sense of comfort experienced by the PWA as well as the conversation topic.

The Current Study

The aim of the current study was to investigate whether CP familiarity affects communication for PWA. Participants completed a collaborative task that required communication in two different conditions: once with a FCP, and once with an UFCP. Participants were in two groups: PWA with a NHC conversation partner, and NHC with a NHC conversation partner. To investigate the question of personal common ground we controlled for the potential influence of two confounding factors. Knowledge of aphasia was controlled for by swapping the CPs of pairs of PWA who were matched on their linguistic and communication impairment profiles. Knowledge of aphasia was also tested through a questionnaire. The sense of comfort was taken into account by asking each familiar and unfamiliar pair to indicate the level of comfort they felt while completing the task with their conversation partner. These research questions were part of a bigger pre-registration (https://osf.io/9xwm7).

A collaborative task was used to elicit naturalistic communication between the participant pairs. Different versions of this task have been used in previous research with NHC (Clark and Wilkes-Gibbs, 1986; Boyle et al., 1994; Clark, 1996; Clark and Krych, 2004; Howarth and Anderson, 2007; Lysander and Horton, 2012) where naturalistic communication is investigated in a controlled lab setting. This experimental setup made it possible to adhere to the previously described framework of real-world communication and to manipulate variables within that framework (Doedens and Meteyard, 2019), see Table 1.

TABLE 1

TABLE 1. Different types of self-initiated repairs and clarification requests that were coded.

To measure the effect of the experimental manipulation on communicative success for PWA and NHC, a selection of key outcome measures was made based on previous literature on CP familiarity with PWA and NHC. Based on research with NHC, measures of trial time and task accuracy were selected. Previous research with PWA suggests that the number of times trouble is identified during conversation, can be indicative of communicative success (e.g., Beeke, 2012). We therefore also included a measure of self-initiated repair (i.e. instances where the “instructor” initiates a self-correction) and other-initiated repair (i.e. instances where the “listener” requests clarification on what has been said) as a measure of communicative success.

Due to the nature of the task, an additional analysis was included (not part of the pre-registration). This analysis aimed to assess the influence of role (instructor or listener) on goal-directed communication. The current study included trials in which PWA and NHC took turns in an “instructor” role, requiring them to actively communicate new information to their CP. Conversely, participants also took on the “listener” role, requiring them to follow instructions from their CP. Previous studies with NHC have assumed no differences in role for measures such as time taken and accuracy (Boyle et al., 1994). Therefore, no difference in roles was expected for NHC for the measures of time and accuracy. However, as PWA present with impairments of language production and comprehension, a difference in performance based on role can be expected. For the number of self-initiated repairs and clarification requests, we expected an effect of role for both groups. Self-initiated repairs are naturally expected to be more frequent when someone speaks more (i.e. the “instructor” role), while Clarification requests are naturally expected to be more frequent when someone is in the “listener” role. Finally, given the inherent variability of the language impairment within the aphasia group, we include a visual representation of the individual difference in scores between conditions (i.e. familiar-unfamiliar), ordered by a standardized measure of aphasia severity. This will provide insight into the spread of individual data-points within the aphasia group, and how this compares to the NHC group.

Analysis addressed the following research questions:

(1) What is the effect of speaker role (instructor/listener) on goal-directed communication?

(2) What is the effect of CP familiarity (personal common ground) on goal-directed, face-to-face communication in aphasia?

(3) Do PWA differ from NHC in how they respond to CP familiarity during goal directed communication?

Based on the existing literature, it was hypothesized that it will be easier for PWA to complete the task with a FCP than with an UFCP, as evidenced by the familiar pair taking less time, requiring fewer repairs, obtaining higher accuracy scores and fewer requests for clarification. Based on the case study by Lubinski et al. (1980), it could be the case that the number of repairs falls into the category of more lower-level behavior which remains stable across conversation partners. In comparison to NHC, we expect PWA to show a similar direction of the effect of CP familiarity. Due to the presence of the language impairment for PWA, we expect the CP familiarity effect to be greater for PWA compared to NHC, i.e. we expect PWA to have more difficulty adapting to communicating with an UFCP, or to benefit more from communicating with their FCP (see Table 2).

TABLE 2

TABLE 2. Hypotheses for each outcome measure, shown for each research question (RQ).

Materials and Methods

Ethics Statement

This study was carried out with ethical clearance from the School of Psychology and Clinical Language Sciences, University of Reading (Ref: 2018-093-LM). All participants provided informed consent prior to taking part in the study. Consent and information forms were adapted to aphasia friendly format for the participants with aphasia.

Participants

Sixteen participants with post-stroke aphasia (42–72 years, M = 60.94, SD = 9.41) and sixteen control participants (NHC, 52–84 years (M = 64.94, SD = 9.66) took part in the current study. PWA and controls were matched for age (t (30) = 1.19, p = 0.245) and years of education (t (29) = −0.07, p = 0.946). Nine male and seven female PWA were recruited through the Aphasia Research Registry of the School of Clinical Language Sciences, University of Reading (British Academy Grant ARP scheme 190023), as well as through local stroke groups. PWA were at least one-year post-stroke (1–14 years, M = 7.04, SD = 3.85) and were native speakers of English prior to the stroke. Exclusion criteria were coexisting neurological diagnoses such as dementia and an inability to provide consent due to severe comprehension difficulties. Seven male and nine female NHC were recruited through the older adult research panel at the School of Psychology, University of Reading. Exclusion criteria were a history of neurological illness. All subjects reported normal or corrected-to-normal vision and hearing.

All participants brought along a FCP to take part in the study with them. The PWA self-nominated a FCP who they spoke to regularly. Six male and ten female FCPs agreed to take part (partner, friend or family member between the ages of 22–72 years, M = 54.12, SD = 15.12, see Table 3 for more details). All FCPs except those labeled child (only ID 48), ex-partner and friend lived in the same house with the PWA. For NHC, partners were recruited as the FCP (aged range 51–79 years, M = 64.12, SD = 7.57, see in the Supplementary Table S1). All FCPs lived in the same house with their partner. All FCPs reported normal or corrected-to-normal vision and hearing and did not report a history of neurological illness.

TABLE 3

TABLE 3. Descriptive for PWA and their familiar conversation partners, ordered by WAB-AQ score (lowest to highest). Scenario Test classification is based on the percentiles of the Dutch norm group, solely used here to provide a descriptive classification.

All PWA completed the Western Aphasia Battery–Revised (WAB-R; Kertesz, 2009). The aphasia quotient score (AQ) ranged from 11.60–94.2 (M = 65.88, SD = 26.59), severities ranging from very severe to mild (see Table 3 for an overview). To obtain a standardized measure of communicative ability, PWA also completed the Scenario Test United Kingdom (Hilari et al., 2018). Scores ranged from 20.25–54 (maximum score = 54, M = 45.64, SD = 8.83; details shown in Table 3). Thirteen out of sixteen PWA had some degree of weakness (hemiparesis) on the right-hand side due to the stroke. All PWA were able to use their unaffected arm and hand effectively. All PWA were mobile enough to attend the experiment at the University clinic. One PWA attended the clinic in a wheelchair.

All participants without aphasia completed the Montreal Cognitive Assessment (MoCA; Nasreddine et al., 2005), a cognitive screening tool for mild cognitive impairment. Scores ranged between 17–30 (M = 27.23, SD = 2.49). Six participants scored below the cut-off score of the test (<26 points; one NHC with score 17; two FCP to NHC with scores 23; three FCP to PWA with scores: 22, 23, 24), suggesting the potential presence of mild cognitive impairment. Due to difficulties in recruiting the PWA subjects, their partners and age- and years of education-matched controls, none were excluded from participation on the basis of their MoCA scores. Following reviewer comments, an additional statistical analysis was run in which these subjects were excluded, as described in the Statistical Analysis section. The MoCA was not administered with the people with aphasia. The heavy reliance of this test on language in its instructions and responses makes this test unsuitable and unreliable for administration with people with existing language processing difficulties.

Procedure

All participants were invited to take part in a study about conversation and different CPs. Background testing with PWA was completed either at the participant’s home or at the School of Clinical Language Sciences, University of Reading. All NHC completed background testing at the University of Reading.

For the experimental session, two participants and their respective FCP were invited to the Speech and Language Therapy Clinic at the University of Reading.

Task

The experimental design consists of a collaborative, referential communication task (Clark and Krych, 2004) that allows pairs to interact and communicate freely, replicating a real-life face-to-face communicative setting. Pairs sat across from each other, in front of identical playmobile rooms (see Figure 1). The view of the other person’s room was blocked by a low barrier. Five items were placed in one room (instructor), while the other room (listener) remained empty with six items placed on the side of the room. Pairs were asked to replicate the setup of the instructor’s room in the listener’s room. They were asked to communicate as they normally would, including the use of any communication aids. Pen and paper were provided for both participants. Participants were instructed not to show items to their CP or to look over the barrier at the other room. In many ways, the current set-up echoes that of PACE in the aphasia literature (Davis and Wilcox, 1985; Davis, 2005). Aphasia friendly images were used to visually support the instruction for all participants. The experimenter left the room for the duration of the task. When the pair completed the task, they pressed a button. The experimenter then re-entered, took a picture of both rooms, and showed the participants the result. Any paper used was collected by the experimenter and the next trial was set up.

FIGURE 1

FIGURE 1. Schematic overview of the experimental setup. View (A) shows a side-view: two participants sitting across from each other at a table, with a low barrier between them. Participants can easily see each other, but the view of the other person’s workspace is obscured by the barrier. View (B) shows the table from above: two identical room layouts. Participant A has five items placed in the room, one distractor object outside of the room. For participant B, all six items are placed on the side of the room. Pen and paper are placed to the left-hand side of the PWA (in case of neglect, hemianopia or hemiparesis), and is provided for both participants. A button at the end of the table (again to the left of the PWA) is used to indicate completion of the task. A low barrier (black bar) blocks the view of the other person’s room, but not the view of their pen and paper.

Each pair (familiar and unfamiliar) completed the game six times: For each trial, roles (instructor/listener) were swapped, resulting in three instructor trials and three listener trials for each participant. The starting role was counterbalanced across participants. A different setup of items was used for each trial, the order of which was randomized for each pair.

The experimental manipulations of the current study can be summarized according to the previously described framework of real-world communication (Doedens and Meteyard, 2019). See Table 4.

TABLE 4

TABLE 4. Description of the experimental manipulation according to the theoretical framework of face-to-face communication.

Materials

An empty Playmobil room with four windows and one door was used for the current experiment. Six Playmobil objects were selected based on psycholinguistic features that have been shown to influence lexical retrieval in PWA (Nickels and Howard, 1995, see in the Supplementary Table S2 for details). The items were selected based on high levels of concreteness, familiarity and imageability, as well as (roughly) low number of phonemes to facilitate naming of the items as much as possible.

Six different room setups were created by placing five Playmobil items in various configurations across the room (see Figure 2). One item (counterbalanced across trials) was a distractor and placed outside of the room. Three additional objects were permanently placed in the same location across all six trials, functioning as reference points for the other objects: 1) a chest of drawers with 2) a television on top and a 3) potted plant in the opposite corner of the room.

FIGURE 2

FIGURE 2. Two examples of item setup in the Playmobil living room. Five items are placed in different locations in the room, one item was always left on the side as the distractor (and did not need to be placed by the listener).

Between conditions, the physical appearance (i.e. the color) of the cat and the hair of the woman was changed to incorporate some variation in the stimuli. Two reference objects were also changed: the potted plant was replaced by a different potted plant and the television was replaced by a set of books. The location of all the items remained constant.

Familiarity Manipulation

In the unfamiliar condition, each participant was matched with another participant’s FCP. PWA were matched with the FCP of a PWA with a similar aphasia profile based on their WAB-AQ score and their communication score on the Scenario Test (Meulen et al., 2010). This way, PWA were matched with an FCP who was unfamiliar at a personal level, but who had experience communicating with someone with roughly similar communication difficulties. Where possible, PWA were also matched on age and gender (see in the Supplementary Table S3 for more details). In the control group, NHCs were matched on gender, age and years of education (in order of priority). For the unfamiliar condition, each NHC was paired up with their matched NHC’s FCP (see in the Supplementary Table S4 for details on matching).

At the beginning of each condition, each participant was asked to rate the familiarity of their CP on an aphasia-friendly Likert scale (0 = this person is a stranger, 5 = I know this person extremely well). For both groups, the FCP was rated higher in familiarity (PWA: M = 3.55, SD = 0.62, NHC: M = 3.97, SD = 0.12) compared to the UFCP (PWA: M = 0.52, SD = 0.92, NHC: M = 0.03, SD = 0.12). The difference in familiarity ratings was significant for both groups (PWA: t (30) = 10.97, p < 0.001, NHC: t (30) = 89.09, p <0 .001).

The order of conditions was not counterbalanced: All participants first completed the familiar condition, followed by the unfamiliar condition. The authors decided against counterbalancing the order of conditions to minimize potential anxieties about communicating with an UFCP for the PWA.

Controlling for Knowledge of Aphasia

To control for knowledge of aphasia, all CPs of PWA filled out a questionnaire testing their knowledge of aphasia (factual knowledge and knowledge on communication stratiegies as described in Rayner and Marshall, 2003). Knowledge of aphasia was similar for FCP (factual: M = 10.1, SD = 3.02, strategies: M = 22.4, SD = 1.9) and UFCP (factual: M = 10.4, SD = 0.98, strategies: M = 22.3, SD = 2.75). A paired t-test showed no significant differences between FCPs and UFCPs (factual knowledge: V = 6, p = 0.854, knowledge of communication strategies: t (6) = 0.16, p = 0.877)¹.

Sense of Comfort With the CP

The degree of comfort participants felt with their FCP and UFCP during the task was taken into account: At the end of each condition, each participant was presented with a statement (“I feel that my partner and I communicate comfortably together”) and a visual 5-point Likert scale (0 = completely disagree, 4 = completely agree). For both PWA and NHC, the degree of comfort they felt with their CP was roughly equal in the familiar (PWA: M = 3.56, SD = 0.51, NHC: M = 3.71, SD = 0.47) and unfamiliar condition (PWA: M = 3.28, SD = 0.52, NHC: M = 3.53, SD = 0.62). A non-parametric paired t-test showed no significant difference between the degree of comfort participants felt with their FCP and UFCP (PWA: V = 18, p = 0.119, NHC: V = 20, p = 0.299).

Coding

All trials were video and audio recorded. Videos of the interactions were coded in ELAN (The Language Archive, 2019). For the purpose of this study, the following measures were coded:

Trial time. All videos were coded for trial time. Trial time was defined as the moment participants started to communicate on a trial (speak, draw, gesture, etc.) until the moment one of the participants pressed the button to signal the experimenter to come into the room.

Task accuracy. Task accuracy was defined as the correct placement of the items in the listener’s room as compared to the instructor’s room as set up by the experimenter. The setup of the instructor’s and listener’s room was photographed at the end of each trial. Both images were scored by two independent judges on accuracy (correct/incorrect) of two aspects of the item: its location (in the room and in relation to other objects), its orientation. For the people, two additional aspects were coded: the action that was undertaken by the item (i.e. standing, sitting, etc.) and the positioning of the arms. For all other objects, the action was always coded as correct, resulting in a maximum score of three per item, and four per person (a maximum score of 20 and a minimum score of 4, examples of low, moderate and high accuracy scores are provided in the Supplementary Figure S1). In case of doubt due to different angles of the pictures, a grid was superimposed on the floor of each image using Kinovea software (Charmant and Contrib., 2006-2011).

Self-initiated repairs. Self-initiated repairs were defined as instances where a participant explicitly attempted to repair or change their own output (often described as the repair initiation; Wilkinson, 2006; Schegloff et al., 1977). A self-initiated repair was always an explicit correction initiated by the interlocutor themselves, without any prompts from the conversation partner. Three different types of self-initiated repairs were coded, partially based on Perkins (1993) (see Table 1). For the word-finding repairs, repetitions of parts of words are expected, but if parts of a word are repeated without revisions, additions or explicit statements of difficulties finding a word, these are not coded as a repair. All self-initiated repairs are coded, regardless of the way in which the repair is resolved (i.e. by the interlocutor themselves, collaboratively with their conversation partner or by the conversation partner). Whether a repair is successful or not was not coded (i.e. whether the correction creates a correct utterance or not, or whether the correct word is produced, or the search is abandoned). Non-verbal instances of self-initiated repairs are also included (e.g. direct gaze at the partner to provide help in a word search, Beeke, 2012). The total number of self-initiated repairs was counted for each trial and participant.

Clarification requests. Clarification requests are defined as instances when one interlocutor indicates to their conversation partner that they have not fully understood what has been said (also described as an “other-initiated” repair; Schegloff et al., 1977). Five types of clarification requests were coded, partly based on Schegloff et al., (1977) (see Table 1). Coding included verbal and non-verbal clarification requests such as clear eye gazes and frowns, or clear shrugs directed at the CP. The total number of clarification requests was counted for each trial and participant.

Coding of the latter two outcome measures is expected to be more subjective compared to the first two outcome measures due to the inherent nature of the coding process (Beeke et al., 2007). Self-initiated repairs were coded by a second rater (native English-speaking speech and language therapy student), resulting in a moderate intraclass correlation coefficient (ICC = 0.74, CI = 0.51–0.87, p < 0.001, calculated in R studio using the psych package version 1.9.12.31; (Revelle, 2020).

Statistical Analysis

All outcome measures showed a non-normal distribution and contained outliers. The outcome measures also showed significant differences in variance between groups. Log-linear transformations did not eliminate the problems of normality or extreme values in the data. To avoid relying on assumptions of normality, a bootstrap procedure was used to obtain a distribution based on resampling of the existing data, from which the test statistic was derived (Wilcox, 2012). Outliers and differences in variance between groups were dealt with by choosing robust analyses based on the median (percentile bootstrap) and 20% trimmed means (bootstrap-t). An alpha threshold of 0.05 was used to determine statistical significance. All analyses were run in R Studio version 1.1.463 (RStudio, 2020). The results from the median analysis are reported in the paper. When there was a difference in outcome, results from both analyses are discussed. For all bootstrapping methods, 10,000 bootstrap samples were used (Rousselet et al., 2019).

First, we ran an omnibus between-by-within-by-within 2 (group: PWA/NHC) x 2 (role: instructor/listener) x 2 (condition: familiar/unfamiliar) robust analyses on all outcome measures: of the median (bwwmcppb in Wilcox, 2012) and the 20% trimmed mean (bwwmcp in Wilcox, 2012). We then ran specific follow up comparisons to answer our research questions.

Research question 1: An effect of role (instructor or listener).

Research question 2: An effect of CP familiarity for PWA.

We analyzed each group separately (PWA or NHC). This helps us to identify patterns for each group of participants, and to address whether role and familiarity have an effect on goal directed communication. Two factors were entered into analysis. First, the condition of familiarity (familiar/unfamiliar), as this was our principle experimental manipulation. Second, the role of the participant (instructor/listener). Role was expected to affect the nature of communication in the goal directed communication task for PWA.

Thus, within subjects 2 (role: instructor/listener) x 2 (condition: familiar/unfamiliar) robust analyses were conducted on all outcome measures: of the median (wwmcppb in Wilcox, 2012), and of the 20% trimmed mean (wwmcpbt in Wilcox, 2012). Planned comparisons were conducted for significant main effects: for a main effect of role, a dependent groups analysis on each level of condition (familiar/unfamiliar) was run on the median and 20% trimmed mean (bootdpci and ydbt, respectively, in Wilcox, 2012). For a main significant effect of condition, the same dependent groups analysis was conducted on each level of role (instructor/listener). The full results of these analyses are reported in the Supplementary Table S5. Results of the planned comparisons are reported in the Supplementary Tables S7–S10.

Research question 3: An effect of CP familiarity for PWA compared to NHC.

We first accounted for the effect of Role (see above) by splitting data into Instructor or Listener trials. We then completed between-by-within 2 (group: PWA/NHC) x 2 (condition: familiar/unfamiliar) robust analyses on all outcome measures: of the median (sppba, sppbb and sppbi in Wilcox, 2012) and the 20% trimmed mean (bwtrimbt in Wilcox, 2012). Planned comparisons on significant main effects of group (PWA vs NHC) were conducted with an independent groups analysis (pb2gen in Wilcox, 2012), to test the effect at each level of condition (familiar/unfamiliar). For a main significant effect of condition, a dependent groups analysis (bootdpci and ydbt, as described above, in Wilcox, 2012) was conducted on each level of group (PWA/NHC). The full results of these analyses are reported in the Supplementary Table S11. Results of the planned comparisons are reported in the Supplementary Tables S13–S16.

To evaluate the influence of participants who scored below cut-off on the MoCA, all statistical analyses reported above were conducted a second time. In these analyses all the sessions (familiar and unfamiliar) in which one participant within a dyad had a MoCA score below the cut-off were excluded. This resulted in the exclusion of data from three dyads in the familiar and unfamiliar conditions, both for PWA and NHC. The results of the 2 × 2 analyses are shown in the Supplementary Tables S6–S12. Any differences in the outcomes of the 2 × 2 × 2 omnibus are mentioned in the results below.

To assess the individual patterns of behavior, a difference score between conditions was calculated for each role: for each participant, the value of each outcome measure for the familiar condition was deducted from the value of the unfamiliar condition. The difference scores were then plotted by group. This visual representation of individual difference scores by aphasia severity is not part of the formal statistical analysis, due to the small and unequal numbers of subjects within the different groups of aphasia severity.

Results

Trial Time

In the omnibus analysis, the analysis based on the median did not show any significant main effects or interactions. The 20% trimmed mean analysis resulted in a main effect group (PWA vs NHC; estimated mean difference = 363.61 s, p = 0.026), with longer trial times for NHC compared to PWA. The main effect of condition was also significant (familiar vs unfamiliar; estimated mean difference = 248.78 s, p = 0.049), with longer trial times for the familiar condition. No other main effect or interaction was significant.

The omnibus analysis without the participants with low MoCA scores based on the median did show a main effect of group (PWA vs. NHC, p = 0.018). In the trimmed means analysis, the main effect of condition was no longer significant (p = 0.052).

Research question 1: An effect of role (instructor or listener).

Research question 2: An effect of CP familiarity for PWA.

PWA

The 2 (role: instructor/listener) x 2 (condition: familiar/unfamiliar) analysis showed a main effect of role (instructor vs. listener; estimated median difference = 156.65 s, p < 0.001), with longer trial times for instructors (median = 332.49, CI = 259.57, 404.11) compared to listeners (median = 251.72, CI = 191.80, 362.96). Planned pairwise comparisons show that the difference in trial time for instructors vs. listeners holds for both conditions (familiar: p = 0.015, unfamiliar: p = 0.035)². For PWA, total trial times were longer when they were in the instructor role as compared to the listener role. See Figure 3.

FIGURE 3

FIGURE 3. Boxplots showing total trial time by condition and group, for each role (instructor/listener).

There was a main effect of condition (familiar vs. unfamiliar; estimated median difference = 167.34 s, p < 0.001), with longer trial times in the familiar condition (median = 363.92, CI = 307.84, 404.11) compared to the unfamiliar condition (median = 251.28, CI = 198.96, 277.92). Planned comparisons show that the difference in trial time between familiar and unfamiliar conditions was significant for the instructor role (p < 0.001) and not when PWA take on the listener role (p = 0.201). In the instructor role, PWA took less time to complete a trial in the unfamiliar condition compared to the familiar condition. In the listener role, trial times were more equal. See Figure 3.

The interaction of role*condition was not significant (estimated median difference = 38.02 s, p = 0.457).

NHC

There were no significant effects (role: estimated median difference = 173.4 s, p = 0.014, condition: estimated median difference = 75.75 s, p = 0.46 = , interaction: estimated median difference = 21.26 s, p = 0.76). For NHC trial times were constant for both roles (instructor/listener) and conditions (familiar/unfamiliar). See Figure 3.

Research question 3: An effect of CP familiarity for PWA compared to NHC.

Instructor Trials

There was no significant main effect of group (PWA/NHC, estimated median difference = 78.37 s, p = 0.199), with PWA and NHC showing similar overall total trial times for Instructor trials.

There was a significant main effect for condition (familiar vs unfamiliar; estimated median difference = 68.09 s, p = 0.01)³, with longer trial times in the familiar condition (median = 384.50, CI = 343.35, 491.88) compared to the unfamiliar condition (median = 284.29, CI = 259.57, 457.81). Planned comparisons within subjects showed that for PWA, total trial times were faster in the unfamiliar condition compared to the familiar condition (see Figure 3). Whilst the main effect of condition was significant, planned comparisons did not show a difference within subjects for the familiar vs unfamiliar conditions for NHC (p = 0.203).

The interaction of group * condition was not significant (estimated median difference = −53.52 s, p = 0.253).

Listener Trials

There was a main effect of group (PWA vs. NHC; estimated median difference = 144 s, p = 0.008). Total trial times were longer for NHC (median = 374.35, CI = 351.61, 457.16) compared to PWA (median = 270.22, CI = 173.27, 365.58). Planned comparisons between subjects showed a significant difference in the unfamiliar condition (p = 0.009), with trial times for PWA significantly faster than for NHC. The same comparison for the familiar condition was not significant (p = 0.158). See Figure 3.

The main effect of condition (estimated median difference = 60.4 s, p = 0.08) and the interaction of group * condition was not significant (estimated median difference = −53.52 s, p = 0.399).

Supplementary Figure S2 shows the changes in total trial times for each group, condition and role by trial. This figure shows a relatively smooth transition in trial times between the final trial of the familiar condition and the first trial of the unfamiliar condition for both groups.

Summary of Results for Trial Time

Total trial times for NHC dyads were slower than PWA dyads (this effect held when participants with low MOCA scores were removed). Total trial times were longer when PWA took on the instructor role, regardless of the familiarity of the CP. In addition, total trial times for PWA were faster for the unfamiliar condition. For NHC, there was no significant difference in trial times in the familiar and unfamiliar conditions, or between the different roles.

Changes at the Level of Individual Dyads

To explore the results descriptively, we plotted the changes in total trial time for each dyad (Figure 4). Data for PWA has been grouped according the severity of aphasia for the PWA participant. In general, the spread of data points for both groups (PWA or NHC) is greater for the Instructor role. There is a trend that, as aphasia severity decreases (moving left to right along the x axis), the distribution of difference scores increases with more dyads showing faster total trial times in the unfamiliar condition (negative values). Note that this is confounded by there being more data points for moderate to mild PWA. However, it is tentative evidence that for PWA who are less severe, total trial times were likely to be faster for the unfamiliar condition.

FIGURE 4

FIGURE 4. Plot showing individual data points for both groups for difference score between familiar and unfamiliar conditions, by role (PWA grouped by WAB categorization). Zero represents no change in total trial time between conditions, negative values indicate a shorter total trial time in the unfamiliar condition compared to the familiar condition.

Task Accuracy

The omnibus analysis showed a main effect of group (PWA vs NHC; estimated median difference = 9.67; p < 0.001), with NHC scoring higher than PWA. There was also a main effect of condition (familiar vs unfamiliar; estimated median difference = −4.33; p = 0.008), with accuracy scores higher in the unfamiliar condition compared to the familiar condition. The main effect of role was not significant (instructor vs. listener; p = 0.707). No two-way interactions were significant. Finally, the three-way interaction was significant (group by role by condition; estimated median difference = −3; p = 0.033), indicating that accuracy scores were different, depending on the group (PWA vs. NHC), role (instructor vs. listener) and condition (familiar vs. unfamiliar). The patterns driving this three-way interaction are explored below.

The omnibus analysis without the participants with low MoCA scores showed the same effects and interactions.

Research question 1: An effect of role (instructor or listener).

Research question 2: An effect of CP familiarity for PWA.

PWA

As in the omnibus analysis, there was a significant main effect of condition (familiar vs. unfamiliar; estimated median difference = −1.67, p = 0.049). Task accuracy scores were higher in the unfamiliar condition (median = 16.17, CI = 15.42, 17.67) compared to the familiar condition (median = 15, CI = 14.08, 17.17). Planned comparisons showed that in the instructor role, PWA did not show a significant change in accuracy scores between familiar and unfamiliar conditions (p = 0.607). In the listener role, the difference in accuracy scores between conditions (familiar/unfamiliar) was significant in the trimmed mean analysis (p = 0.007, median analysis: p = 0.062). Accuracy was higher in the unfamiliar condition compared to the familiar condition. It therefore seems that the main effect of condition (familiar vs. unfamiliar) for PWA was driven by the improvement in accuracy scores in the listener role (see Figure 5).

FIGURE 5

FIGURE 5. Boxplots showing total accuracy score (out of 20) by condition and group, for each role (instructor/listener).

There was no significant main effect of role (estimated median difference = 0.67, p = 0.538) and no significant interaction of role*condition (estimated median difference = 1.83, p = 0.167).

NHC

There was a significant main effect of condition (familiar vs. unfamiliar; estimated median difference = −0.67, p = 0.015), with NHC obtaining higher accuracy scores in the unfamiliar condition (median = 18.75, CI = 18.33, 19.0) compared to the familiar condition (median = 18.33, CI = 17.17, 18.67). Planned pairwise comparisons showed a significant effect of condition for NHC in the instructor role as measured by the 20% trimmed means analysis (p = 0.043, median analysis: p = 0.131), but not for the listener role (p = 0.182). As instructors, NHC obtained higher accuracy scores in the unfamiliar condition compared to the familiar condition, driven more by the significant improvement in scores in the instructor role.

There were no significant effects of role (estimated median difference = −0.67, p = 0.173) nor an interaction of role*condition (estimated median difference = −0.33, p = 0.338).

Research question 3: An effect of CP familiarity for PWA compared to NHC.