Objects, faces, and spaces: Organizational principles of visual object perception as evidenced by individual differences in behavior

What are the diagnostic dimensions on which objects truly differ visually, and do these dimensions provide the foundation for the organizational principles of visual object perception as evidenced by individual differences in behavior? Using data-driven methods, we utilized a deep convolutional neural network to construct a visual object space extracted from deep layer activations for a reference set of objects. The first two dimensions of object space capture attributes that distinguish one object from another and may map onto the anatomical organization of the ventral visual stream of non-human primates, but its existence in humans is unclear. If object space underlies human visual cognition, this should have a measurable effect on people’s object discrimination. We focused on the so-called face quadrant of object space, as there are considerable individual differences in face discrimination abilities, and a lively debate has revolved around whether such abilities are specific to faces. In this preregistered study, we collected data from a large (N=511) heterogeneous sample to amplify individual differences in visual discrimination. 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 faces and other objects had to be discriminated. Stimuli were carefully picked out of tens of thousands of images to either match or not match with the coordinates of faces in object space. Results showed that face discrimination did not rely on completely domain-specific abilities but also tapped into mechanisms that supported other object discrimination. Specifically, people who struggled with telling apart faces also had difficulties with discriminating other objects from the face quadrant of object space. To the best of our knowledge, the current study provides the first behavioral evidence for the existence of an object space in human visual cognition. ### Competing Interest Statement The authors have declared no competing interest.