Auditory joint attention skills: Development and diagnostic differences during infancy.

To date, joint attention skill assessments have focused on children's responses to multimodal bids (RJA) and their initiation of bids (IJA) to multimodal spectacles. Here we gain a systematic view of auditory joint attention skills using a novel assessment that measures both auditory and multimodal RJA and IJA. In Study 1, 47 typically developing (TD) children were tested 5 times from 12 to 30 months to document auditory joint attention skill development. In Study 2, 113 toddlers (39 TD, 33 autism spectrum disorder [ASD], and 41 non-ASD developmental disorders [DD]; average age 22.4 months) were tested to discern the effects of ASD. Our findings fit well within the established depiction of joint attention skills with one important caveat: auditory items were far more difficult to execute than multimodal ones. By 24 months, TD children passed multimodal RJA items at the near-ceiling level, an accomplishment not reached even by 30 months for auditory RJA items. Intentional communicative IJA bids also emerged more slowly to auditory spectacles than to multimodal spectacles. Toddlers with DD outperformed toddlers with ASD on multimodal RJA items but toddlers in both groups rarely passed any auditory RJA items. Toddlers with ASD often monitored their partner's attention during IJA items, albeit less often than toddlers with DD and TD toddlers, but they essentially never produced higher-level IJA bids, regardless of modality. Future studies should investigate further how variations in bids and targets affect auditory joint attention skills and probe the relation between these skills and language development.