Eye Gaze Behavior at Turn Transition: How Aphasic Patients Process Speakers' Turns during Video Observation

Abstract

Abstract■ The human turn-taking system regulates the smooth and precise exchange of speaking turns during face-to-face interaction. Recent studies investigated the processing of ongoing turns during conversation by measuring the eye movements of noninvolved observers. The findings suggest that humans shift their gaze in anticipation to the next speaker before the start of the next turn. Moreover, there is evidence that the ability to timely detect turn transitions mainly relies on the lexicosyntactic content provided by the conversation. Consequently, patients with aphasia, who often experience deficits in both semantic and syntactic processing, might encounter difficulties to detect and timely shift their gaze at turn transitions. To test this assumption, we presented video vignettes of natural conversations to aphasic patients and healthy controls, while their eye movements were measured. The frequency and latency of event-related gaze shifts, with respect to the end of the current turn in the videos, were compared between the two groups. Our results suggest that, compared with healthy controls, aphasic patients have a reduced probability to shift their gaze at turn transitions but do not show significantly increased gaze shift latencies. In healthy controls, but not in aphasic patients, the probability to shift the gaze at turn transition was increased when the video content of the current turn had a higher lexicosyntactic complexity. Furthermore, the results from voxel-based lesion symptom mapping indicate that the association between lexico-syntactic complexity and gaze shift latency in aphasic patients is predicted by brain lesions located in the posterior branch of the left arcuate fasciculus. Higher lexico-syntactic processing demands seem to lead to a reduced gaze shift probability in aphasic patients. This finding may represent missed opportunities for patients to place their contributions during everyday conversation. ■

Multimodal Communication in Aphasia: Perception and Production of Co-speech Gestures During Face-to-Face Conversation

“…In aphasia, lexico-syntactic processing with regard to language comprehension and speech production is impaired (Caplan et al, 2007 ). This means that, with increasing complexity of the speech content, the detection of a relevant time point for turn transition becomes more difficult for patients with aphasia (Preisig et al, 2016 ). Therefore, it is conceivable that co-speech gestures gain higher relevance in aphasia, because face-to-face interactions impose higher task demands on aphasic patients than on healthy participants.…”

The importance of situated language use for aphasia rehabilitation

“…As lexico-syntactic information increased healthy controls were shown to benefit more from variance in intonation in predicting upcoming turns. PWA did not show this reliance on intonation cues (Preisig et al, 2016). In conclusion, there is some support for the idea that PWA can utilise prosody in production to communicate effectively, though most of the support for this claim relies on observational research with non-fluent PWA.…”

What is Functional Communication? A Theoretical Framework for Real-World Communication Applied to Aphasia Rehabilitation

“…As lexico-syntactic information increased, healthy controls were shown to benefit more from variation in intonation in predicting upcoming turns. People with aphasia did not show this reliance on intonation cues (Preisig et al, 2016), suggesting that perhaps people with aphasia cannot rely on linguistic prosody, or are unable to integrate information from the two channels. In conclusion, there is some support for the idea that people with aphasia can utilise prosody in production to communicate effectively, with most of the support for this claim coming from observational research with people with non-fluent aphasia.…”

“…Whether or not people with aphasia can use prosody to support comprehension in conversation is unclear. The findings so far indicate that the integration of information from multiple channels may be more difficult for people with aphasia, or that people with aphasia may have difficulty flexibly changing the weight they give to different sources of information in order to resolve ambiguity or complexity (e.g., using prosody to aid comprehension of syntactically complex sentences; Preisig et al, 2016).…”

“…A larger body of research has shown that expanding the conversation partner’s knowledge of aphasia and training them to use communication strategies can improve overall communication with people with aphasia (e.g., Cruice et al., 2018 ; Howe et al., 2008 ; Kagan et al., 2001 ; Lesser & Algar, 1995 ; Lindsay & Wilkinson, 1999 ; Nykanen et al., 2013 ; Pound et al., 2000 ; Rayner & Marshall, 2003 ; Simmons-Mackie et al., 2010 ; Wilkinson & Wielaert, 2012 ). Most of these studies are based on the idea that communication strategies employed by the non-aphasic conversation partner can create an environment that enables the person with aphasia to communicate optimally.…”