What can iconic gestures tell us about the language system? A case of conduction aphasia

Speech and language therapists rarely analyse iconic gesture when assessing a client with aphasia, despite a growing body of research suggesting that language and gesture are part of either the same system or two highly integrated systems. This may be because there has been limited research that has systematically analysed iconic gesture production by people with aphasia.

The aim was to determine whether the gesture production of a participant with conduction aphasia was able to provide information about her language system.

The iconic gestures produced by a participant with conduction aphasia (LT) and five control participants produced during the retelling of a cartoon were analysed. In particular, the iconic gestures produced during lexical retrieval difficulties (co-tip-of-the-tongue (co-TOT) gestures) were compared with the iconic gestures produced during fluent speech (co-speech gestures).

It was found that LT produced 57 co-speech gestures that were similar in form to the co-speech gestures produced by the control participants (mean = 34.2, standard deviation (SD) = 22.2). LT also produced an additional eleven co-TOT gestures that were unlike her co-speech gestures and unlike the co-speech gestures produced by the control participants. While the co-speech gestures depicted events, the co-TOT gestures depicted 'things' (for example, objects and animals). Furthermore, all but one of the co-TOT gestures produced by LT was classified as a shape-outline gesture, whereas co-speech gestures were rarely classified as shape-outline gestures. LT also produced a new type of gesture that has not previously been described in the literature: a homophone gesture. This co-TOT homophone gesture depicted the homophone of the target word. The iconic gestures produced by LT suggest that she had an intact semantic system but had difficulties with phonological encoding, consistent with a diagnosis of conduction aphasia. This raises the possibility that iconic gesture production can provide evidence about the level of breakdown in the language system.

A larger study exploring the gestures produced by participants with aphasia is required. The research also highlights the importance of including gesture assessments in SLT's work with adults with acquired language disorder.