Latency to Share Interest at 12 Months Is Associated with Joint Attention Trajectories in Infants at High and Low Risk for ASD

Background:   Low-level initiation of joint attention (IJA-low; looking to the examiner and alternating gaze between toy and examiner) does not differ between 12-month olds who are later diagnosed with ASD and those who develop typically.  However, IJA is impaired in older children with ASD.  We explored individual differences in time to orient to an examiner after viewing an interesting event in 12-month olds at high (HR) and low risk (LR) for ASD to examine reaction time or speed to convert a solitary experience into a shared social experience. We hypothesized that social motivation would be greater and therefore latencies would be shorter in LR infants than in HR infants later diagnosed with ASD.  There is limited research on social reaction time in ASD, but older children with ASD do not differ from neurotypical controls in inspection time on computerized nonsocial tasks. Investigation of skills that are intact in infancy but impaired in childhood is expected to reveal useful targets for early intervention.

Objectives:  (1) Evaluate latency to share interest in HR and LR 12-month olds;  (2) Evaluate relations between latency to orient and frequency of IJA concurrently and longitudinally.

Methods:   Participants were 105 infants at high and low risk for ASD. Evaluations at 36 months indicate that 50 were developing typically (TD); 30 showed signs of social and/or language delays; and 25 met criteria for ASD. We administered the Early Social Communication Scales (ESCS; Mundy et al., 2003) at 12 and 18 months. During the wind-up toy portion of the ESCS, the time between presentation of the wind-up toy and first look to the examiner was measured.  Latency times were averaged across trials for each participant.  IJA-low at 12 and 18 months was coded according to the ESCS manual.

Results:   Preliminary results show no difference in average latency time between groups (Mean (Standard Deviation) in seconds: ASD = 6.4 (5.3); Atypical outcome = 6.3 (4.3); TD = 7.9 (5.7)). However, latency to orient across groups was negatively correlated with frequency of IJA-low (r=-.59, p<.01). Additionally, the relation between latency to orient at 12 months and growth in IJA-low from 12 to 18 months was moderated by outcome classification (F(3,52)=5.41, p<.01):  the TD group showed a positive relation between latency and IJA growth, and the ASD group showed a negative relation.  

Conclusions:   Latency to convert one’s own enjoyment of an event to a shared social experience did not differ between 12-month olds later diagnosed with ASD and those with other atypical or TD outcomes.  Longer latency to disengage from the non-social stimulus and orient toward the examiner appears beneficial among TD infants whereas infants who take longer to orient to the examiner and who are later diagnosed with ASD show decreases in IJA-low from 12-18 months.  Social orienting is present in all outcome groups and occurs at comparable speeds.  Mechanisms of experience-sharing are evident but function differently among groups, arguing for interventions that focus on transforming social glances into opportunities for shared enjoyment in infants at heightened risk for ASD.