Reduced spatial frequency differentiation and sex-related specificities in fearful face detection in autism: Insights from EEG and the predictive brain model.
EEG shows autistic adults have weaker neural tuning to spatial-frequency sequences during fearful face detection, and sex differences matter.
01Research in Context
What this study did
Lacroix et al. (2024) hooked 19 autistic and 19 non-autistic adults to EEG. The team flashed fearful faces that changed in fine or coarse detail. They asked: does the brain track these detail shifts, and does sex matter?
Each picture swapped its level of detail many times per second. The researchers measured how well the fusiform face area followed the swap rhythm.
What they found
Autistic adults missed more fearful faces. Their fusiform response barely moved when detail levels flipped. Non-autistic brains kept perfect time with the swaps.
Autistic women showed extra activity across the whole back of the brain. Autistic men did not. Sex shapes the neural picture.
How this fits with other research
Van der Donck et al. (2023) used the same adult EEG setup and saw no group difference. The clash is real: one lab finds typical brain timing, the other finds broken timing. The difference may lie in the task. Stephanie used quick identity swaps; Adeline used detail-level swaps that tap predictive coding.
Kuang et al. (2025) pooled 25 fMRI studies and found weaker left inferior frontal activity in autistic people during any facial emotion task. Adeline’s EEG result now shows the timing breakdown starts earlier, in the fusiform face area itself.
Schaaf et al. (2015) first noted that autistic girls have dampened early face-wave responses. Adeline moves this sex split into adulthood and links it to spatial-frequency tracking, not just face detection.
Why it matters
If your client misses subtle facial cues, check how you present faces. High-contrast, unchanging photos may help more than rapidly shifting video clips. For girls on the spectrum, watch for scattered activation that could mask fatigue or overload. Try slower face-reveal games and give extra wait time before asking them to read emotion.
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02At a glance
03Original abstract
Face processing relies on predictive processes driven by low spatial frequencies (LSF) that convey coarse information prior to fine information conveyed by high spatial frequencies. However, autistic individuals might have atypical predictive processes, contributing to facial processing difficulties. This may be more normalized in autistic females, who often exhibit better socio-communicational abilities than males. We hypothesized that autistic females would display a more typical coarse-to-fine processing for socio-emotional stimuli compared to autistic males. To test this hypothesis, we asked adult participants (44 autistic, 51 non-autistic) to detect fearful faces among neutral faces, filtered in two orders: from coarse-to-fine (CtF) and from fine-to-coarse (FtC). Results show lower d' values and longer reaction times for fearful detection in autism compared to non-autistic (NA) individuals, regardless of the filtering order. Both groups presented shorter P100 latency after CtF compared to FtC, and larger amplitude for N170 after FtC compared to CtF. However, autistic participants presented a reduced difference in source activity between CtF and FtC in the fusiform. There was also a more spatially spread activation pattern in autistic females compared to NA females. Finally, females had faster P100 and N170 latencies, as well as larger occipital activation for FtC sequences than males, irrespective of the group. Overall, the results do not suggest impaired predictive processes from LSF in autism despite behavioral differences in fear detection. However, they do indicate reduced brain modulation by spatial frequency in autism. In addition, the findings highlight sex differences that warrant consideration in understanding autistic females.
Autism research : official journal of the International Society for Autism Research, 2024 · doi:10.1002/aur.3209