Developmental changes in infants’ categorization of anger and disgust facial expressions.

Abstract

For decades, scholars have examined how children first recognize emotional facial expressions. This research has found that infants younger than 10-months can discriminate negative, within-valence facial expressions in looking time tasks, while children older than 24-months struggle to categorize these expressions in labeling and free-sort tasks. Specifically, these older children, and even adults, consistently misidentify disgust expressions as anger. While some scholars have hypothesized that young infants would also be unable to categorize anger and disgust expressions, this question has not been empirically tested. In addition, very little research has examined developmental changes in infants' perceptual categorization abilities with high arousal, within-valence emotions. For this reason, the current study tested 10-and 18-month-olds in a looking time task and found that both age groups could perceptually categorize anger and disgust facial expressions. Furthermore, 18-month-olds showed a heightened sensitivity to novel anger expressions, suggesting that, over the second year of life, infants' emotion categorization skills undergo developmental change. These findings are the first to demonstrate that young infants can categorize anger and disgust facial expressions and document how this skill develops and changes over time.

Categorical Perception of Facial Emotions in Infancy

“…As noted earlier, Ruba et al. () reported that 10‐month‐olds categorize the anger/disgust contrast in faces. However, Ruba et al.…”

“…It is possible that 5‐month‐olds’ failure to exhibit categorical perception of anger/disgust contrasts in Experiments 1 and 2 is because these emotions are not fully differentiated by 5 months, and it takes longer for the categorical boundary between anger and disgust to develop (Ruba et al., ). One reason for this might be the overlap in several physical facial features (e.g., face muscular structure) associated with angry and disgusted expressions (Aviezer, Hassin, Bentin, & Trope, ).…”

“…Recently, Ruba, Johnson, Harris, and Wilbourn () reported that 10‐ and 18‐month‐old infants do categorize stimuli within a valence class, specifically anger versus disgust. Infants were sequentially habituated to images of four different actresses all displaying the same emotion (i.e., all angry or all disgusted) and then tested on four different types of test trials (i.e., novel individual displaying novel emotion, novel individual displaying familiar emotion, familiar individual displaying novel emotion, and familiar individual displaying familiar emotion).…”

Do Preverbal Infants Understand Discrete Facial Expressions of Emotion?

“…Only a handful of studies have used negative facial expressions during both habituation and test. These studies indicate that 4- to 18-month-olds can form a category of anger (i.e., after habituation to anger expressions) and differentiate this category from novel sad, fear, and disgust expressions (Ruba, Johnson, Harris, & Wilbourn, 2017; Schwartz et al, 1985; Serrano et al, 1992). Moreover, 10- and 18-month-olds can form a category of disgust and differentiate this category from anger expressions at test (Ruba et al, 2017).…”

The development of categorisation and conceptual thinking in early childhood: methods and limitations

“…Finally, most studies assume that concepts are perceptual distillates. Categories would result from comparing and abstracting physical properties of objects (e.g., Bomba & Siqueland 1983;Casasola & Ahn 2018;Quinn & Johnson 2000;Ruba et al, 2017;Stavans & Baillargeon 2018;Younger & Fearing 1999, 2000. However, this prospect raises hard problems at the epistemological level (for an in-depth discussion, see Alessandroni, 2020;Alessandroni & Rodríguez, in press).…”