High and Low Level of initiating nonverbal communication (proportion). Note. AC, autistic children (N = 23); DD, developmental delay (N = 23); TD2, 18–20 months normal (N = 22); TD1, 13–15 months normal (N = 22); IJA-L, initiating joint attention—low; IJA-H, initiating joint attention—high; IR-L, initiating requesting—low; IR-H, initiating requesting—high; ISI, initiating social interaction. * p < .05; ** p < .01