The study, co-authored by Professor Chris Jarrold of Bristol’s School of Experimental Psychology and published in Development and Psychopathology, found that the mechanism for using ‘inner speech’ or ‘talking things through in their head’ is intact in children with autism but they do not always use it in the same way as typically developing children do.
The psychologists found that the use, or lack of, thinking in words is strongly linked to the extent of someone’s communication impairments which are rooted in early childhood.
However, the researchers suggest teaching and intervention strategies for children targeted at encouraging inner speech may make a difference. These strategies, which include encouraging children to describe their actions out loud, have already proven useful for increasing mental flexibility among typically developing children.
It is also suggested that children with autism spectrum disorder (ASD) could, for example, benefit from verbal learning of their daily schedule at school rather than using visual timetables – currently a common approach.
Lead author, Dr David Williams, lecturer in the Department of Psychology at Durham University, said: “Most people will ‘think in words’ when trying to solve problems, which helps with planning or particularly complicated tasks. Young, typically developing children tend to talk out loud to guide themselves when they face challenging tasks.
“However, only from about the age of seven do they talk to themselves in their head and, thus, think in words for problem-solving. How good people are at this skill is in part determined by their communication experiences as a young child.”
One out of every 100 people in the UK has ASD, which is diagnosed on the basis of a set of core impairments in social engagement, communication and behavioural flexibility. Children with autism often miss out on the early communicative exchanges when they are young which may explain their tendency not to use inner speech when they are older. This relative lack of inner speech use might contribute to some of the repetitive behaviours which are common in people with autism.
In the study, those individuals with more profound communication impairments also struggled most with the use of inner speech for complex tasks. People with ASD did, however, use inner speech to recall things from their short-term memory.
Dr Williams said: “These results show that inner speech has its roots in interpersonal communication with others early in life, and it demonstrates that people who are poor at communicating with others will generally be poor at communicating with themselves.
“It also shows that there is a critical distinction between being able to express yourself verbally and actually using silent language for problem-solving. For example, the participants with ASD in our study were verbally able, yet did not use inner speech to support their planning.”
Caroline Hattersley, Head of Information, Advice and Advocacy at the National Autistic Society, said: “This study presents some interesting results and could further our understanding of autism. If the findings are replicated on a wider scale they could have a significant impact on how we develop strategies to support children with the disability.”
In the study, 15 high-functioning adults with ASD and 16 comparison participants were asked to complete a commonly used task which measures planning ability, called the Tower of London task. This task consists of five coloured disks that can be arranged on three individual pegs. The aim of the task is to transform one arrangement of disks into another by moving the disks between the pegs, one disk at a time, in as few moves as possible. This type of complex planning task is helped by ‘talking to yourself in your head’.
The participants did the task under normal conditions as well as under an ‘articulatory suppression’ condition whereby they had to repeat out loud a certain word throughout the task, in this case, either the word ‘Tuesday’ or ‘Thursday’. If someone uses inner speech to help them plan, articulatory suppression prevents them from doing so and will detrimentally affect their planning performance, whereas it will have little impact on the planning performance of someone who doesn’t use inner speech.
The results showed that whilst almost 90 per cent of normally developing adults did significantly worse on the Tower of London task when asked to repeat the word, only a third of people with autism were in any way negatively affected by articulatory suppression during the task. This suggests that, unlike neurotypical adults, participants with autism do not normally use inner speech to help themselves plan.
The participants also completed a short-term memory task to asses the use of inner speech in short-term recall.
The research was funded by a City University London Research Fellowship to the lead researcher.
‘Inner speech is used to mediate short-term memory, but not planning, among intellectually high-functioning adults with autism spectrum disorder’, Williams, Bowler and Jarrold, published by Cambridge University Press in Development and Psychopathology, January 2012.