In new research published in Psychological Bulletin, a team of scientists from Macquarie University and Griffith University have found that individuals with autism tend to produce fewer gestures like pointing and emblematic gestures compared to their neurotypical peers, but the difference in iconic gestures, which represent concrete objects, is less apparent. The comprehensive review highlights the complexity and diversity within the autism spectrum, paving the way for more nuanced approaches in both research and practice.
“Although there are multiple criteria for diagnosing autism, a reduced frequency of gesture production is often used as part of screening,” said study authors Nicola McKern, Nicole Dargue, and Naomi Sweller in a joint statement to PsyPost.
“However, research evidence on gesture production by autistic vs neurotypical individuals is inconsistent. So, we were interested in clarifying whether autistic individuals really do produce fewer gestures than neurotypical individuals. Rather than running an empirical study that might not provide any more clarity than currently exists in the literature, we opted to conduct a systematic review and meta-analysis that synthesized the findings from 31 different studies.”
A meta-analysis is a statistical technique that combines data from multiple studies to draw broader conclusions. The researchers meticulously combed through numerous databases, searching for relevant studies published from 2003 to 2022. They looked for studies that used standard diagnostic criteria for autism and included a neurotypical comparison group. Importantly, the studies had to have clear measures of gesture frequency – essentially, how often participants used gestures in communication.
The final analysis included data from 1,561 participants in total. This participant group comprised 701 individuals diagnosed with autism and 860 individuals without autism (neurotypical individuals). Studies were conducted across 12 countries, mainly in the United States and China. Early childhood was the most represented age group, followed by middle childhood and adulthood.
The study’s findings confirmed some long-held beliefs while challenging others. One key discovery was that autistic individuals generally used fewer gestures compared to neurotypical individuals. However, the study brought an interesting nuance to light regarding iconic gestures – those that depict a concrete object, action, or event. Contrary to what might be expected, autistic and neurotypical individuals used these gestures at similar rates.
“We found that across studies, while autistic individuals tended to produce certain types of gestures less frequently than neurotypical individuals, they produced other types of gestures at comparable or higher frequencies than neurotypical individuals,” the researchers explained. “Deictic gestures are pointing gestures, used to indicate the location or direction of a person or object. Emblematic gestures convey meaning on their own without speech, for example, thumbs up to indicate ‘OK.’ Iconic gestures depict concrete objects, or actions, such as holding your hands up cupped towards each other to indicate a ball.”
“We found that autistic individuals produced less deictic and emblematic gestures, but comparable numbers of iconic gestures, with some studies showing autistic individuals produced more, and some less, iconic gestures, than neurotypical individuals. There is huge variability in the extent to which autistic individuals gesture. So, it is important for people to remember that just because someone produces gestures, it doesn’t necessarily mean they’re not autistic. There are exceptions to the prevailing belief that autistic individuals use fewer gestures.”
Another important aspect of the study was how it identified several factors that influenced these gesture frequency differences. These included the age of the individuals, the setting in which the gestures were observed (like a structured task or a more naturalistic setting), and whether the observer was familiar or unfamiliar to the person gesturing.
“It is important to note that these findings varied, depending on several other factors,” McKern, Dargue, and Sweller said. “For example, the age of the individual, how familiar they were with the person observing the gestures, and how much speech they produced. More studies should be run to more closely examine the extent to which these other factors might impact differences in gesture production between autistic and neurotypical individuals.”
This study opens several avenues for future research. One key area is the exploration of gesture use in different contexts and life stages, especially among adolescents and adults with autism, who were underrepresented in the existing studies. Additionally, there’s a need to understand the impact of gender and co-occurring conditions on gesture use in autism, areas that have not been extensively explored yet.
Moreover, future research could delve deeper into how individual differences, such as cognitive abilities and the propensity to ‘mask’ or camouflage autistic traits, might affect gesture use. This understanding is crucial for developing more tailored communication strategies and interventions that can better support individuals with autism in various social contexts.
“Gestures are incredibly important for social communication, from early childhood onwards,” the researchers added. “Because autistic people have been thought to gesture less, the criteria for diagnosing autism are weighted in such a way that if an individual gestures less during the assessment, they are more likely to be diagnosed with autism. It is very important for clinicians to be aware that there are exceptions, and an autistic individual may not show reduced gesture production.”
The study, “Comparing Gesture Frequency Between Autistic and Neurotypical Individuals: A Systematic Review and Meta-Analysis“, was published online on October 9, 2023.