By: Inas Essa
Adults usually use a simplified form of affective speech while talking to children to make words more melodic and easier to pronounce. This form of speech is called motherese; the language spoken globally by mothers to their newborns and toddlers in which a horse becomes horsie, a dog becomes doggie, etc. Although this way of communication may be favored by some babies, children with Autism Spectrum Disorder (ASD) do not typically respond well to it. A new study published in January 2022 in the journal Nature Human Behavior indicates the reason behind this issue.
Baby Talking to Children with ASD
Previous research has highlighted that the infant-direct speech, motherese, is preferred by infants compared to adult-like speech, as it better captures their attention and plays a key role in creating emotional bonding and fostering learning experiences between child and parents. However, children with ASD struggle to connect well with this form of speech.
In the new study, the researchers worked on detecting the regions of the brain and neural mechanisms responsible for the normal and impaired development of a child's response to baby talk. They tried to figure out the “why” behind the impaired response and concluded that the significantly reduced behavioral preference for motherese in autism is related to the impaired development of temporal cortical systems that normally respond to parental affective speech. This may also have long-term consequences when children "tune out".
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ASD and Problems with Social Attention
It is well known that reduced response to social information is an early sign of ASD in children as they face challenges in sustaining attention to social information in general. In the new study, researchers at the University of California (UC) San Diego School of Medicine included some techniques to highlight the regions of the brain responsible for a child's response to baby talk.
The senior author of the study, Eric Courchesne, Ph.D., professor of neuroscience at UC San Diego School of Medicine said that the approach employed in this study generates new insights about brain development in children with autism, related to objective information about social preference and social attention. "For the first time, we are seeing what the possible brain impact is for children with autism who fail to pay attention to social information," he added.
The research team hypothesized that ASD infants experience impaired development of innately driven neural mechanisms that respond to motherese. So, they worked on measuring neural responses to mild, moderate affective speech and motherese.
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Language Development and Response to Motherese
The researchers found a link between early-age social and language development and a child's neural responses to speech. This means that infants with ASD and toddlers with the poorest neural responses to motherese also displayed the most severe poorest language outcomes besides the greatest impairment of behavioral preference and attention toward this form of speech. On the other hand, typically developing infants showed the strongest neural responses and affinity to motherese.
Moreover, when the researchers investigated the relation between eye-gaze patterns to neural and behavioral responses, their earlier findings were confirmed. They found that the superior temporal cortex, a region of the brain that processes sounds and language, responded more weakly to motherese in ASD children, who also had the poorest social abilities and lowest eye-tracking attention to motherese.
"Our conclusion is that lack of behavioral attention to motherese speech in ASD involves impaired development of innate temporal cortical neural systems that normally would automatically respond to parental emotional speech," said study co-author Karen Pierce, Ph.D., professor of neurosciences at UC San Diego School of Medicine and co-director of Autism Center of Excellence with Courchesne.
Finally, the team indicated that these findings could be useful in developing further diagnostic tools and biomarkers for the early identification of ASD. Also, it would be helpful in further clarifying how ASD dramatically affects toddlers in different ways.
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