Processing Speed	Receptive Vocabulary	Single-Word Reading
Number of experts completing	9	10	9
Device and webcam type (webcam: internal or external)	1 Mini tablet 5 Laptop internal 1 Laptop external 2 Desktop external	6 Laptop internal 1 Laptop external 3 Desktop external	5 Laptop internal 4 Desktop external
Screen size	1 <10” 3 10–12” 3 12–18” 4 19+”	2 10–12” 3 13–18” 4 19+”	2 10–12” 3 13–18” 4 19+”
Paradigm relevance (M, SD, range) (1=highly relevant to 4=not relevant)	1.6 (0.7, 1–3)	1.6 (0.8, 1–3)	2.4 (1.0, 1–4)
Clarity of instructions (M, SD, range) (1=very clear to 4=very difficult to follow)	1.1 (0.3, 1–2)	1.2 (0.4, 1–2)	1.3 (1.0, 1–4)
Quality of audio (M, SD, range) (1=very clear to 4=not clear)	1 (0)	1.7 (0.9, 1–4)	1.1 (0.3, 1–2)
Quality of pictures / words (M, SD, range) (1=high, 2=medium, 3=low)	1 (0)	1.1 (0.3, 1–2)	1.0 (0)
Timing of administration (M, SD, range) (1=very fast to 3=neither fast or slow to 5=very slow)	3 (0.3, 3–4)	3.1 (0.3, 3–4)	2.9 (0.3, 2–3)
Difficulty level (M, SD, range) (1=very appropriate to 4=inappropriate)	1.7 (0.5, 1–2)	2.4 (0.9, 1–4)	2.3 (1.3, 1–4)
Possible concerns (n)
Too many easy targets	0	0	0
Too many moderate diff targets	0	0	0
Too many hard targets	0	4	2
Too few easy targets	0	1	1
Too few moderate diff targets	0	0	0
Too few hard targets	0	0	0
Targets too close together	2	0	0
Targets too far apart	0	0	0
Target array not appropriate	0	0	0

Note. Clinician-scientist experts did not provide feedback on the social attention paradigm as this was adapted from our prior eye tracking investigations and the stimuli for this paradigm had already received prior input from clinician-scientist experts in their development. Specific qualitative feedback is not included but was used to improve the administration flow and provide better instructions to the parent facilitating the administration.