Minimal Differences in Auditory and Visual Oddball Tasks in Autism: A Systematic Review and Meta-Analysis.
Oddball MMN isn’t a reliable autism biomarker—effect sizes are negligible and variability is individual, not diagnostic.
01Research in Context
What this study did
Melegari et al. (2025) pooled every paper they could find on oddball tasks in autism.
They compared brain waves called MMN between autistic and non-autistic people.
Both beep sounds and flashing pictures were counted.
What they found
Across all studies the MMN difference was tiny—close to zero.
No clear pattern showed up for either hearing or vision tests.
The authors say MMN is too variable to be a handy autism marker.
How this fits with other research
Chuah et al. (2025) also published a 2025 review but saw reduced MMN linked to daily-living skills.
The clash is only on the surface: Min looked at how MMN size relates to skills inside the autism group, while G asked if MMN separates autism from typical groups.
Older work like Vlaskamp et al. (2017) and Matsuzaki et al. (2019) did report smaller MMN; those single studies sit inside G’s bigger pile and get watered down by lots of null results.
Chien et al. (2026) found shorter MMN in unaffected siblings, hinting that genetics can tweak the wave even when autism is absent—another reason MMN is shaky as a diagnostic line.
Why it matters
If you hoped MMN would give you a quick brain test for autism, shelve that plan.
Use your session time to teach skills, not chase unreliable EEG bumps.
When you see MMN used in new gadget ads, ask for the effect size first.
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02At a glance
03Original abstract
Autism is a neurodevelopmental condition that presents with significant changes in sensory processing, and which has recently been associated with differences in sensory expectations. One method for measuring sensory expectations (i.e., predictions) is via oddball paradigms, in which a deviant stimulus is presented following a series of repeated stimuli. In EEG signals, this deviance elicits a characteristic mismatch negativity (MMN) response, which acts as a neural signature of deviance detection and perception. Given the growing focus on sensory prediction in autism, a number of studies have now employed the oddball paradigm, with mixed results. We conducted a meta-analysis to better understand the utility of oddball paradigms in evaluating sensory prediction differences in the autism population. A comprehensive literature search queried the PubMed database for empirical auditory and visual oddball studies comparing autistic and non-autistic individuals. Statistical analyses were all conducted in R. We estimated true effect sizes and characterized the effects of various study characteristics on effect size using a multi-level random effects model and robust variance estimation (RVE). Publication bias and study quality were also assessed. Although individual studies have reported differences, the results of this meta-analysis suggest no significant group differences between autistic and non-autistic individuals in auditory or visual oddball perception, recognition, or neural signatures. When used in autism research, auditory and visual oddball MMN responses may not inherently capture changes in sensory prediction, and significant findings may be related more to individual variability than diagnostic group.
Journal of autism and developmental disorders, 2025 · doi:10.1073/pnas.1506582112