A Novel Measure for Quantifying Infant Engagement during Social Interactions with Their Caregivers

Background: Infant-caregiver interactions provide the ideal framework for social learning: as infants engage with their caregivers, caregivers, in turn, modify their behavior to the needs of their infant, creating cycles of contingency that scaffold infants’ emerging abilities. These reciprocal social exchanges are highly engaging to typically-developing (TD) infants: they display positive affect, and often become distressed when the contingency is removed (Tronick et al., 1975). By contrast, reduced engagement with the social world is not only a defining feature of Autism Spectrum Disorder, but may also be a significant contributor to emerging social disability, as active engagement during reciprocal exchanges is a necessary condition for social learning to occur (Rose et al. 2011). Unfortunately, few quantifiable, objective measures of infant engagement exist, limiting inquiry into this important area.

The present study capitalizes on previous reports of TD infant engagement during contingent social interaction to test whether patterns of eye-blinking can be used as a measure of infant engagement. This method is based on the fact that eyeblinks interrupt the flow of visual information; as a result, viewers unconsciously adjust the timing of their own eye-blinks to minimize the likelihood of missing important information. Consequantly, the more engaged the viewer is, the more likely they will be to inhibit blinking (Shultz, Klin, & Jones, 2011, PNAS). This measure could provide new inroads for quantifying the subjective experiences of infants as they interact with their caregivers, enabling future research into disruptions to foundational mechanisms of social learning in ASD.

Objectives: To determine if patterns of eye-blinking can be used to measure engagement during contingent and non-contingent social interactions in 3- to 5-month-old TD infants.

Methods: Eye-tracking data were collected from 3- to 5-month-old TD infants (N=14) while viewing 3 conditions: 1) a prerecorded non-contigent video of a stranger; 2) a live video feed of the infant’s caregiver (see Figure 1); and 3) prerecorded non-contingent videos of the infant’s caregiver. Mean blinks per minute (bpm) were calculated and compared across conditions.

Results: Paired samples t-tests revealed that infants demonstrated lower rates of eye-blinking during the contingent condition (mean bpm=4.82, SD=4.89) compared with the non-contingent stranger condition (mean=9.04, SD=8.40; p<.05). A trend towards lower rates of eye-blinking during the contingent condition compared to the non-contingent caregiver condition (mean bpm=10.01, SD=11.08) was also observed (p=0.10) (see Figure 2). Immediate next steps include coding of eye-blink data in an additional N=24 TD infants and N=7 infants who received a diagnosis of ASD at 24 and 36 months.

Conclusions: Preliminary findings suggest that eye-blink rates can provide a useful index of infant engagement, with TD infants blinking less during contingent, compared with non-contingent, social interactions. This study advances a useful framework and novel measure for future work investigating the influence of engagement on learning within the context of reciprocal social interactions in typical development and in ASD.