What is aphasia?
Imagine having a conversation. You know what you want to say, but you cannot find the words to communicate it. We have all experienced the frustration of a word being just out of reach on the tip of our tongue. For most of us, this happens only occasionally, but for people with aphasia, it can be a daily challenge.
Aphasia is a language impairment that most commonly results from a stroke to the left side of the brain. A stroke occurs when a blood vessel in the brain becomes blocked or bursts, which can disrupt the flow of essential oxygen and nutrients to the areas of the brain that support language production and comprehension. For this reason, strokes can cause lasting damage and have long-term impacts on the ability to express and understand language across spoken, written, and signed modalities.
It is estimated that 25% - 50% of strokes result in aphasia (ASHA.org). Aphasia does not affect a person’s intellect or their social communication skills. Therefore, despite their difficulties with language, people with aphasia can still be effective communicators. One of the best ways to support communication in aphasia is through multimodality. Multimodal tools such as gestures, facial expressions, drawing, writing, and manipulating objects enhance communication for everyone. However, for people with aphasia who struggle to communicate verbally, these tools become even more essential for conveying meaning.
Gesture stands out as a particularly valuable tool for supporting effective communication in aphasia. Our hand gestures are a rich source of information capable of depicting objects, actions, locations, and more. Further, we carry this resource on our body, making it accessible and convenient. We know that gesture serves a variety of communicative and cognitive functions for non-brain-injured speakers and listeners, but what about people with aphasia? Do people with aphasia use gestures effectively despite their language impairment? And how do their gestures differ from those of non-brain-injured adults? We explore these questions below.
How do people with aphasia gesture?
When it comes to gestures, some convey more meaning than others. Consider iconic gestures: these gestures depict the shape, size, action, movement, or position of an object. For example, a speaker might hold a hand up to their ear to depict a phone call or flap their arms to represent a flying bird. Some iconic gestures are redundant with speech, conveying the same information (e.g., saying “I walked to the store” while alternating two downward-facing fingers to produce a walking gesture). Other iconic gestures are complementary to speech, providing unique or supplemental information beyond what is in speech (e.g., saying, “I went to the store” while producing a walking gesture). Finally, some iconic gestures are essential, providing crucial information in the absence of speech (e.g., producing a walking gesture in response to the question, “How did you get to the store?”).
In general, people with aphasia tend to gesture at higher rates than non-brain-injured adults (i.e., producing a higher number of gestures per number of words). Their gestures are often iconic, carrying rich meaning, and are more likely to depict complementary or essential information that is not conveyed by speech. In fact, a recent study found that over half of the iconic gestures people with aphasia produced contained complementary or essential information (Stark et al. 2023). This highlights how important gestures can be for people with aphasia compared to speakers without spoken language impairment.
Do all people with aphasia benefit from gesture?
Although people with aphasia share a common impairment in language, there are many factors that differ across individuals. For example, people differ in demographic factors (e.g., age and level of education), time since stroke, the location and size of their brain damage, the features of their language impairment (e.g., word retrieval errors, difficulty understanding), and its severity. This prompts us to question whether every person with aphasia benefits equally from using gestures to enhance their communication.
What we know so far is that people with aphasia who have difficulty producing language seem to use gestures more effectively than those who have trouble understanding it. Additionally, the severity of aphasia can also influence how people use gestures. People with severe language impairment may rely more on gesture to communicate. However, severe aphasia can also co-occur with other problems like difficulty performing intentional movements, which can make using gestures harder (Chick et al. 2024).
Although more work is needed to identify who is most likely to benefit from gesture, researchers are making increasing efforts to understand how these various factors relate to gesture production in people with aphasia.
What comes next?
The more we learn about gesture in aphasia, the more questions come up. So far, we have mostly talked about the gestures that people with aphasia use themselves. But what about the gestures produced by their conversation partners? Can those gestures help people with aphasia understand a message more easily? And what happens when gestures are used in real conversations?
These are some of the questions that Martina Mellana is exploring in her PhD research. They also lead us to a broader question: what does aphasia look like in signed languages, when the hands are already the primary modality of communication? There is evidence that aphasia can also affect sign language, with many symptoms that parallel those seen in spoken-language aphasia. However, compared with research on spoken-language aphasia and gesture, sign language aphasia remains much less well understood, and further research is needed.
References
Stark, B. C., & Oeding, G. (2023). Demographic, neuropsychological, and speech variables that impact iconic and supplementary-to-speech gesturing in aphasia. Gesture, 22(1), 62-93.
Chick, I., Garrard, P., Buxbaum, L. J., & Vigliocco, G. (2024). Co-speech Gesture Production in Spoken Discourse Among Speakers with Acquired Language Disorders. In Spoken Discourse Impairments in the Neurogenic Populations: A State-of-the-Art, Contemporary Approach (pp. 133-150). Cham: Springer International Publishing.
Credits
- Writer: Martina Mellana
- Editor: Anna Mai
- Dutch translation: Lieke Herraets
- German translation: Carmen Ramoser
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