How toddlers respond to baby talk (also known as ‘motherese’) could be an early indicator of autism, according to new research.
The study, published in JAMA Network Open, found that young children who showed low levels of attention towards baby talk were more likely to be autistic.
Motherese is a form of speech characterised by simple grammar and language, high pitch, and slow tempo. Speaking to your baby in this way has been shown to improve attention and learning and is associated with improved language acquisition, affective engagement, and emotional reactivity.
However, autistic children often show “unusual and sometimes absent responses to auditory information in their environment,” the study states. This includes failing to respond when their name is called and exhibiting poor understanding of word meanings.
The authors of the study therefore set out to investigate whether level of attention toward motherese speech can be used as a diagnostic classifier of autism.
A total of 653 toddlers aged 12 to 48 months were included in the study, and the researchers used eye tracking tests to measure how fixated the child was on a film when the main actress was speaking in motherese style.
This film was played three times, and each time it was played alongside a different film. One depicted traffic (noisy, moving vehicles on a highway), one techno (moving shapes with musical sounds), and another the same film but the actress was speaking in a monotone voice (known as the ‘flat affect’).
The movies were available for approximately 60 seconds, and toddlers used the direction of their gaze to control the amount of time each movie was played.
Areas of interest were then drawn on and the results were analysed. The children were then split up into five groups: autism, autism features, typical development, delays, and typical sibling of an autistic proband.
Non-autistic toddlers were found to almost uniformly fixate on the motherese speech with a median level of 82.25% and 80.75% across the two tests. However, among autistic toddlers, there was a wide range, spanning from 0% to 100%, and this group fixated on the motherese videos significantly less than all other diagnostic groups.
When a cut-off level of 30% or less fixation on motherese speech was used, toddlers in this range were diagnostically classified as autistic with high accuracy.
The researchers say the study’s results suggest that unusually low levels of attention to motherese may be beneficial not only for early autism diagnosis and prognosis but also as a possible therapeutic target.
They conclude: “Overall, attention to motherese speech is a fundamental property of early development that can be rapidly measured using eye tracking.
“In this diagnostic study, a cut-off level of 30% fixation or less on motherese speech was accurate at identifying toddlers who were diagnostically classified as having [autism].
“Identifying toddlers who show unusually low levels of attention to motherese speech is potentially beneficial not only for early [autism] screening, diagnosis, and prognosis but also for possible therapeutic targets and may be a key pathway toward precision medicine.”
