Toward ecological validity in expression discrimination: Forced-choice saccadic responses to posed and naturalistic faces.

Abstract

Certain faces draw more attention than others. For example, faces signaling emotion elicit quicker and more accurate eye movements compared to faces signaling more neutral displays. However, the use of faces with posed expressions staged to represent particular emotion categories might have inflated these effects, and it remains largely unknown whether we can effectively discriminate facial displays under more naturalistic conditions. Here, we used forced-choice saccadic responses to investigate the speed and accuracy of discrimination between happy, threatening, and neutral facial expressions. Further, we compared these markers of performance when using posed or naturalistic databases. Participants (N = 40) viewed happy/neutral and neutral/threatening face pairs and were tasked with saccading toward the "happiest" face. We found that participants rapidly distinguished happy expressions from neutral expressions in both posed and naturalistic face trials, though this bias was amplified when distinguishing faces with posed expressions. Further, interference from threatening faces more strongly disrupted neutral expression selection in posed compared to naturalistic face trials. These results confirm that naturalistic faces drive similar behavioral biases to posed faces in expression discrimination tasks. However, detailed analyses of continuous eye position revealed that, despite increased levels of visual noise, naturalistic faces elicited accurate eye movements faster than posed faces. These findings are a vital step forward in the field of social perception, paving the way from tightly controlled laboratory experiments to more ecologically valid approaches. (PsycInfo Database Record (c) 2025 APA, all rights reserved).