Abstract
We have already demonstrated infants' sensitivity to facial movement by measuring brain activity during infants viewing facial biological motion using NIRS (Ichikawa et al., 2010). Generally, facial movement facilitates recognition of facial expressions. While the intense expression is enough expressive to be recognized in still, the subtle expression can be recognized only when presented in motion (Ambadar et al., 2005, Bould & Morris, 2008). Although it is well-known that infants recognize static intense facial expression (Barrera & Maurer, 1981; Nelson & Ludermann, 1986, Serrano et al., 1982), it has not been examined whether infants recognize a dynamic subtle expression. The present study investigated the issue using a familiarization–novelty procedure.
To generate dynamic subtle expression, we videotaped a female performing either angry or happy facial expressions and extracted below three frames from each video clip; the first frame (neutral), the 6th frame (subtle expression), and the 13th frame (peak expression). We presented two frames of a neutral and a subtle expression alternatively as a dynamic facial expression.
3–8 month-old infants were first familiarized with a subtle expression of either anger or happiness. In the familiarization trials, infants viewed repeatedly presented the dynamic subtle expression of anger (or happiness) for 15 sec × 4 trials. Following the familiarization, infants were tested with a pair of peak expressions of familiarized anger (or happiness) and of novel happiness (or anger) expressions for 10 sec × 2 trials. We hypothesized that if infants recognize an expression from dynamic subtle expression, they would show a novelty preference for a novel expression. We found that infants could learn a subtle angry expression faster than a subtle happy expression. The results might suggest that infants recognize and learn the distinctive facial expression even in subtle expression by dynamic presentation.
This research was supported by a Grant-in-Aid for Scientific Research (20119002, 21243041) from Japan Society for the Promotion of Science.