Auditory processing in autism spectrum disorder: Mismatch negativity deficits.
Kids with ASD miss everyday sound changes early, then over-react once they notice.
01Research in Context
What this study did
Vlaskamp et al. (2017) compared brain waves of autistic and neurotypical kids.
They used a simple oddball sound task while kids watched a silent movie.
Electrodes on the scalp recorded early change-detection (MMN) and later attention-shift (P3a) waves.
What they found
Autistic children showed a smaller MMN wave, meaning their brains noticed sound changes less automatically.
They also showed a larger P3a wave, meaning once a change was noticed, it grabbed too much attention.
The pattern points to weak early filtering and strong but late orienting to sounds.
How this fits with other research
Chuah et al. (2025) pooled many MMN studies and found the smaller wave links to poor daily living skills, not social symptoms.
Matsuzaki et al. (2019) extended the same idea using MEG: minimally-verbal kids had the most delayed mismatch fields, tying the marker to language level.
Melegari et al. (2025) meta-analysis seems to disagree, reporting no overall MMN difference, but they mixed wide age ranges and tasks; narrow child samples like Chantal’s still show the deficit.
Chien et al. (2026) flipped the lens: unaffected siblings with larger P3a had better memory, hinting the same wave can be protective in different genetic contexts.
Why it matters
You can view MMN/P3a as an objective hearing check during assessment.
If MMN is small, give extra warning before changing instructions or rooms.
If P3a is large, teach the child to return attention with a cue like “ears on me.”
These quick brain markers may help you group kids who need sensory priming versus those who need attention reset training.
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02At a glance
03Original abstract
UNLABELLED: Children with autism spectrum disorders (ASD) often show changes in (automatic) auditory processing. Electrophysiology provides a method to study auditory processing, by investigating event-related potentials such as mismatch negativity (MMN) and P3a-amplitude. However, findings on MMN in autism are highly inconsistent, partly due to small sample sizes in the studies and differences in MMN paradigms. Therefore, in the current study, MMN and P3a amplitude were assessed in a relatively large sample of children with ASD, using a more extensive MMN paradigm and compared with that of typically developing children (TDC). Thirty-five children (aged 8-12 years) with ASD and 38 age and gender matched TDC were assessed with a MMN paradigm with three types of deviants, i.e., frequency, duration and a combination of these two. MMN elicited by duration and frequency-duration deviants was significantly reduced in the ASD group. P3a-amplitude elicited by duration deviants was significantly increased in the ASD group. Reduced MMN in children with ASD suggests that children with ASD may be less responsive to environmentally deviant stimuli at an early (sensory) level. P3a-amplitude was increased in ASD, implying a hyper-responsivity at the attentional level. In addition, as similar MMN deficits are found in schizophrenia, these MMN results may explain some of the frequently reported increased risk of children with ASD to develop schizophrenia later in life. Autism Res 2017, 10: 1857-1865. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Automatic detection of deviant sounds in the environment, such as upcoming traffic, is often affected in children with autism spectrum disorders (ASD). Mismatch negativity (MMN) is a way to quantify automatic deviancy detection, using electroencephalography. In this study, auditory MMN was assessed in 35 children with ASD and 38 matched control children, revealing significantly reduced MMN in the ASD group. This may indicate that children with ASD are less able to automatically detect environmentally deviant stimuli.
Autism research : official journal of the International Society for Autism Research, 2017 · doi:10.1002/aur.1821