Table 6.

Candidate neurophysiological biomarkers investigated in at least two studies, with at least one positive finding, in relation to autism spectrum disorder

Biomarker	Number of significant effects	Number of non‐significant effects	Direction	Rate of replication (%)
MEG/EEG measures
P3 amplitude	3	1	Three increased	75
Alpha power	5	3	Five decreased	62.5
N1 amplitude	5	1	Three increased, two decreased	50
N170 amplitude	1	1	One decreased	50
N2 amplitude	2	2	Two increased	50
Mismatch negativity (MMN) amplitude	4	3	Three increased, one decreased	43
Gamma power	22	11	Thirteen increased, nine decreased	39
P1 amplitude	1	2	One increased	33
P2 amplitude	1	2	One decreased	33
Theta power	1	2	One decreased	33
Delta power	1	3	One decreased	25
Beta power	1	10	One decreased	9
Cardiovascular measures
Heart rate	3	0	One increased, two decreased	67
Heart rate variability ‐ high frequency	3	0	One increased, two decreased	67
Acoustic startle reflex
Acoustic eye‐blink startle latency	3	0	Three increased	100
Acoustic eye‐blink startle magnitude	10	5	Ten increased	66
Acoustic eye‐blink startle habituation	1	8	One decreased	11
Oculomotor measures and visual attention
Exploration of visual stimuli	4	0	One increased, three decreased	75
Visual attention ‐ biological motion	4	1	One increased, three decreased	60
Perseveration on visual stimuli	8	4	Six increased, two decreased	50
Visual attention ‐ social	22	33	Eight increased, 19 decreased	34
Visual attention ‐ non‐social	11	10	Five increased, six decreased	28
Pupillometry
Pupil light reflex ‐ dilation	3	1	Two slower	75
Pupil light reflex ‐ constriction	7	3	Six slower, one faster	60
Pupil diameter	4	4	Two increased, two decreased	25

MEG – magnetoencephalography, EEG – electroencephalography