Concurrent development of facial identity and expression discrimination.

Kirsten A Dalrymple,Jed T Elison,M Ida Gobbini,Matteo Visconti Di Oleggio Castello,Peter James Hills

doi:10.1371/journal.pone.0179458

Abstract

Facial identity and facial expression processing both appear to follow a protracted developmental trajectory, yet these trajectories have been studied independently and have not been directly compared. Here we investigated whether these processes develop at the same or different rates using matched identity and expression discrimination tasks. The Identity task begins with a target face that is a morph between two identities (Identity A/Identity B). After a brief delay, the target face is replaced by two choice faces: 100% Identity A and 100% Identity B. Children 5-12-years-old were asked to pick the choice face that is most similar to the target identity. The Expression task is matched in format and difficulty to the Identity task, except the targets are morphs between two expressions (Angry/Happy, or Disgust/Surprise). The same children were asked to pick the choice face with the expression that is most similar to the target expression. There were significant effects of age, with performance improving (becoming more accurate and faster) on both tasks with increasing age. Accuracy and reaction times were not significantly different across tasks and there was no significant Age x Task interaction. Thus, facial identity and facial expression discrimination appear to develop at a similar rate, with comparable improvement on both tasks from age five to twelve. Because our tasks are so closely matched in format and difficulty, they may prove useful for testing face identity and face expression processing in special populations, such as autism or prosopagnosia, where one of these abilities might be impaired.

Highlights

Face processing is a complex cognitive ability that we rely on to process important information about others, such as identity, emotional expression, direction of attention, sex, and age
We found that the overall accuracy increased with age, Χ2(1) = 57.83,p < .001, and that the two tasks were matched in difficulty, as revealed by the non-significant main effect of Task, Χ2(1) = 0.44, p = 0.51 and non-significant interaction between Age and Task, Χ2(1) = 0.12, p = 0.73
The present study was designed to directly compare the development of these two face processing abilities, in tasks that were matched in format and difficulty

Summary

Introduction

Face processing is a complex cognitive ability that we rely on to process important information about others, such as identity, emotional expression, direction of attention, sex, and age. One influential model of face processing [1] proposed a clear separation between what was referred to as ‘expression analysis’ and components dedicated to identity recognition called ‘face recognition units’ and ‘person identity nodes’. Development of facial identity and expression discrimination system for face processing that assigned the processing of changeable aspects of faces (such as for facial expression) to the Superior Temporal Sulcus (STS), and the processing of invariant aspects of faces (such as for facial identity) to the Lateral Fusiform Gyrus These models propose that the separation between the processing of facial identity and expression occurs early, and that these processes remain separate. There is evidence that these abilities may separate at a young age: a 5-year-old boy with severe prosopagnosia demonstrated normal facial expression processing [15]

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