The PDDST parent
questionnaires, Stage III by Dr. Bryna Siegel begins at 0-6 mos.
; e.g., a social smile by 2 mos., reciprocal goos & coos by 4 mos., raising arms to be picked up by 6 mos.Studies of younger siblings of kids with ASD who fail the M-CHAT at 18 mos. show gradually decreased eye
-to-face gaze from 6 mos. on. Qualitative impairments in early social skills are hard to spot & not always present.