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Co-speech gesture during speech errors in healthy ageing: metaphoric gesture as conceptual scaffolding for lexical retrieval
Poster A85 in Poster Session A, Wednesday, September 30, 11:00 am - 1:00 pm, Wangari Maathai and Lise Girardin
T R Williamson1,2, Margaret Newson1,2, Kris Kinsey1,3, Anna E Piasecki1,2,3; 1Brain, Language, and Behaviour Laboratory, UWE Bristol, UK, 2Southmead Hospital, North Bristol NHS Trust, UK, 3School of Social Sciences, UWE Bristol, UK
Introduction. Whether co-speech gesture facilitates lexical retrieval, conceptualisation, or neither is a long-running architectural question (Krauss, 1998; Kita et al., 2017). Critical evidence — gesture during disfluency — has converged against facilitation (Graziano & Gullberg, 2018; Kısa et al., 2022, 2024). Two design choices limit this evidence as a mechanistic test: cartoon-retelling and painting-description tasks impose minimal cognitive demand, and Maclay–Osgood disfluency categories index dialogue surface (filled pauses, repetitions, repairs) rather than the underlying psycholinguistic process. Both are addressable by combining demand-modulated everyday conversation with clinical-linguistic speech-error categories that index process directly. Methods. Forty-eight monolingual British English speakers (Mage = 39, range 19–64; 28F) held 25-minute dyadic conversations with a deception-blind confederate, structured as a 5-minute warm-up, a 10-minute screen-absent topic-card phase normed for complexity, and a 10-minute screen-present phase that occluded the confederate's torso. Manual gestures (n = 8,309) were annotated in ELAN by gesture role (Cohen's κ = .854, 88.8% agreement). Overt speech errors were independently coded using clinical-linguistic categories indexing the impaired psycholinguistic process. Co-occurring gesture–error events were extracted from synchronous timecodes. The corpus is fully described in Williamson et al. (2026). Results. Of the 8,309-gesture corpus, 581 gestures co-occurred with overt speech errors (~7%). Anomia and dysfluency dominated; lexical access and speech planning were the most commonly implicated processes. Three convergent findings constrain the architectural account. Role specificity: Bonferroni-corrected directional residual analysis on a gesture-role × process contingency table showed metaphoric gestures significantly overrepresented in lexical-access errors (standardised residual = 2.545; p = .038). Age effects: a general linear model showed older participants gestured more during speech errors (F(1,47) = 14.16, p < .001, partial η² = .235), and a composite PCA factor combining metaphoric-gesturing rate and lexical-access-error rate strongly predicted age (F(1,47) = 17.41, p < .001, η² = .27). Modulation by demand and visibility: a Poisson GLMM revealed a significant Occlusion × Complexity interaction on gesture-during-speech-error counts (Exp(B) = 1.554, 95% CI [1.055, 2.287], p = .026); occlusion suppressed gesture-during-speech-error rate during simple-topic conversations only (Bonferroni contrast ratio = 1.646, p = .005), with no change during complex topics. Conclusion. The data are inconsistent with two architectural accounts. Facilitation qua prevention (Kısa et al., 2022; 2024) — gesture deployed pre-error to keep retrieval online — predicts uniform suppression under occlusion, not the demand-conditional pattern observed. A no-facilitation account (Graziano & Gullberg, 2018) predicts no role-specificity. The data fit facilitation qua reparation: gesture recruited at detected lexical-retrieval failure as conceptual scaffolding, with metaphoric specificity suggesting the scaffold is spatial-conceptual. The age-related increase is consistent with documented lexical-retrieval slowing (Marini & Andreetta, 2016) and with compensatory gesture in clinical populations (De Kleine et al., 2024). Findings align with the Gesture-for-Conceptualization hypothesis (Kita et al., 2017) and motivate study of gesture-recruitment architecture under retrieval failure in aphasia.
Topic Areas: Signed Language and Gesture, Disorders: Developmental