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skills. At 24 months, compared to infants with typical development, both groups of
infants with later ASDs had lower frequencies of using words, vocalizations,
declarative pointing, social gaze, and orienting to name.
Mars, Mauk, and Dowrick (1998) found that difficulties in social and
communicative behaviors such as joint attention deficits were less frequent in the
videos of infants with later diagnoses of PDD-NOS than in the videos of children with
autistic disorder between 12 and 30 months. Bernabei, Camaioni, and Levi (1998)
examined the social interaction, communication, language and functional and
symbolic play of infants later diagnosed with autism from birth to 24 months (0-6, 6-
12, 12-18 and 18-24 months). They reported on low frequency of communicative
gestures (i.e., pointing, showing, and ritualized requests), pretend play and
conventional social games from 6 to 12 months as well as on regression in socio-
interactive behaviors. Baranek (1999; Baranek, et al., 2005) found that impairments
in response to name calling, aversion to touch, and orientation to visual stimuli
differentiated between infants at 9-12 months who later on received an ASD diagnosis
and infants who were later on diagnosed with developmental delays, yet play with
objects did not differ among the groups (Baranek et al., 2005). Colgan et al. (2006)
also examined the emergence of gestures used in social interactions (i.e., frequency,
initiation, prompting, and types of gestures) and reported that restricted types of
gestures were strongly associated with the ASD group. However neither the
frequency of gestures nor the initiation of gestures were significantly associated with
being later assigned to the ASD group.
Maestro et al. (2001) examined the development of symbolic activity and
intersubjective behaviors (i.e., an early manifestation of the ability to represent other's
state of mind) of infants who later developed ASDs compared to infants with typical