Objects, faces, and spaces

What are the organizational principles of visual object perception as evidenced by individual differences in behavior? What specific abilities and disabilities in object discrimination go together? In this preregistered study (https://osf.io/q5ne8), we collected data from a large (N=511) heterogeneous sample to amplify individual differences in visual discrimination abilities. We primarily targeted people with self-declared face recognition abilities on opposite sides of the spectrum, ranging from poor to excellent face recognizers. We then administered a visual foraging task where people had to discriminate between various faces, other familiar objects, and novel objects. Each image had a known location in both face space and object space, which both were defined based on activation patterns in a convolutional neural network trained on object classification. Face space captures the main dimensions on which faces visually differ from one another while object space captures the main diagnostic dimensions across various objects. Distance between two images in face/object space can be calculated, where greater distance indicates that the images are visually different from one another on dimensions that are diagnostic for telling apart different faces/objects. Our results suggest that there simply are not any measurable stable individual differences in the usage of face space. However, we furthermore show that people who struggle with telling apart different faces also have some difficulties with visual processing of objects that share visual qualities with faces as measured by their location in object space. Face discrimination may therefore not rely on completely domain-specific abilities but may tap into mechanisms that support other object discrimination. We discuss how these results may or may not provide support for the existence of an object space in human high-level vision.