Can Emotional Expressions “Motivate” Infants to Individuate Other-Race Faces in Infants Following Perceptual Narrowing?

• In Event: 1-032 - Infants’ capacity to individuate people

Integrative Statement

Perceptual narrowing occurs in human infants for other-race faces: younger infants differentiate faces within own- and other-race classes, whereas older infants exposed primarily to own-race faces better differentiate own- over other-race faces (Kelly et al., 2007). Given the adaptive advantages of preserving sensitivity to infrequent stimuli, researchers are examining variables that reduce narrowing. Because prior adult and infant work showed that angry and happy expressions enhance face processing (Ackerman et al., 2006; Becker et al., 2011; Gross & Schwarzer, 2010), we investigated whether these expressions would restore infant recognition of other-race faces following narrowing.

Experiment 1 demonstrated narrowing for Caucasian infants viewing neutral Asian faces in a procedure with one face presented on 2 15-s familiarization trials and then the familiar face paired with a novel face on 2 10-s test trials. Looking time was recorded and test-trial novelty preference was computed as LT to novel face/(LT to familiar + novel face) x 100. Whereas 3-month-olds (N=16) differentiated the faces, 6-month-olds (N=16) did not (Figure 1). Experiment 2 used the same procedure with Caucasian 6-month-olds, but with angry (N=16) or happy (N=16) familiarization and test faces. In these cases, the Asian faces were discriminated (Figure 1). Experiments 3 and 4 yielded comparable results for Caucasian 6- and 9-month-olds tested with African faces (Figure 2, N=16 per condition).

An ANOVA was performed on the individual novelty preference scores for the 6-month-olds presented with neutral versus angry versus happy Asian faces in Experiments 1-2 and the 9-month-olds presented with neutral versus angry versus happy African faces in Experiments 3-4. The only significant effect was that of Expression, F(2,90)=8.07, p=.0006. Tukey’s HSD indicated that the mean novelty preferences for angry faces (M=65.08%, SD=13.98) and happy faces (M=60.68%, SD=12.38) were significantly greater than that for neutral faces (M=50.26%, SD=17.93), p<.01, in each case.

A question concerns the mechanism by which emotional expressions facilitate recognition. Expressions might create more salient stimuli that result in more looking time and greater likelihood of processing identity. However, post-narrowing infants displayed equivalent familiarization looking times for neutral, angry, and happy faces, F(2,45)<1.42, p>.25.

A second possibility is that adding emotion creates more discriminable stimuli. However, this possibility was contradicted by equivalent pairwise stimulus similarity ratings obtained from 72 Caucasian adults (12 per condition) on a 1 to 5 Likert scale (1=not similar, 5=very similar) for the neutral, angry, and happy Asian and African faces, F(2,33)<1.27, p>.29, in both cases. The similarity ratings were supported by image-based analyses of the low-level properties of the images (luminance, contrast, hue, saturation). For no properties were the angry faces and happy faces each found to be more distinct from one another than the neutral faces.

Without support for the lower-level mechanisms, we are intrigued by the possibility that infants are processing the communicative intent of the expressions (Frith, 2009; Senju & Csibra, 2008). Angry and happy faces are individuated because anger poses threat and happiness invites affiliation. Expression thus creates motivation to individuate other-race faces (Hugenberg et al., 2011).

Authors

• Paul C Quinn, University of Delaware
  Presenting Author

• Kang Lee, University of Toronto
  Non-Presenting Author

• Olivier Pascalis, Universite Grenoble Alpes
  Non-Presenting Author

• Naiqi G Xiao, Princeton University
  Non-Presenting Author