Bradley Duchaine - US grants

Face processing is central to social interaction. We use faces to identify people, determine what they are feeling, what they are attending to, and trait judgments based on faces contribute to how we behave toward others (e.g., Is this person trustworthy? Attractive to me?). In the human brain, face recognition is mediated by a distributed cortical network that includes visual, limbic, and prefrontal areas. However, the nature of the computations underlying face processing and the function of the different areas contributing to face processing remain unclear. To better understand the computational and neural basis of face processing, we will carry out behavioral and neuroimaging studies with participants who have suffered brain damage that disrupts their ability to recognize faces. This condition is known as acquired prosopagnosia, and our lab has developed the world's largest database of participants with acquired prosopagnosia (N=20 and growing). These prosopagnosic participants have varied face perception impairments as well as varied damage to the face processing network. This project will advance our knowledge of face processing in individuals with normal face processing and will also be the first step toward the development of a classification system for acquired prosopagnosia. Such a classification system would be valuable, because different types of prosopagnosia are likely to be responsive to different types of interventions.

The primary objective of the current proposal is to test fundamental cognitive and neural predictions of two influential models of face. Previous studies investigating face perception in prosopagnosia have examined only a few abilities in small samples. The proposed project, in contrast, will investigate a wide range of face perception abilities in at least 20 patients drawn from the PI's prosopagnosia database (http://www.faceblind.org). The studies will address three primary aims. They will test and, if necessary, revise the cognitive structure of a broad model of face perception (Aim 1), test and revise a model of facial trait perception (Aim 2), and test the neural predictions of these two models (Aim 3). The proposed project will yield two main intellectual outcomes: evaluation of the face perception models and their revision as necessary, and a taxonomy of acquired prosopagnosia. Creation of a taxonomy of acquired prosopagnosia will be a major advance, because the current practice of grouping together different types of acquired prosopagnosia hampers efforts to understand the condition and develop rehabilitation methods. Media coverage of our findings is likely to increase public awareness of prosopagnosia. The face perception battery created will be made freely available as user-friendly programs that will be useful for both researchers and clinicians. Undergraduate researchers, many of whom are members of minorities under-represented in science, will get hands-on experience in this project.

Face recognition is central for social interaction, and people with face recognition impairments su?er from di?culties that impact their personal and professional lives. Previous research has indicated that face recognition ability is strongly in?uenced by where on the face people look, and that this tends to be consistent for a given person. For example, some people always look between the eyes, while others look close to the tip of the nose or the mouth. It has also been shown that each person recognizes faces best when they look near the location they normally ?xate. These habits suggest that each person's face processing and eye movement systems have been mutually shaped, or tuned, to optimize recognition ability. However, little is known about how these factors contribute to di?erences in face recognition ability, how they change in adults, and how they develop in children. This project will address these fundamental questions, and could prove important in treating patients with deficits in face recognition.

The project will consist of three components: In the project?s ?rst component, the investigators will examine where adults between the ages of 18 and 50 usually look on faces and where their ?sweet spot? (optimal match between fixation and processing) lies. Preliminary results indicate that adults tend to look lower on faces as they age, indicating that the tuning of our face system changes even in adulthood. This study will examine whether this holds for a larger sample by comparing across ages and will explore the dynamics of gaze changes for individuals by measuring the same participants once and then again three years later. In the second component, the investigators will examine where people with developmental prosopagnosia (DP), a condition characterized by severe face recognition impairments, look on faces and whether they show a good match between where they look and their sweet spot. In the third component, the investigators will determine where children look on the face and how their tuning to faces changes as they age. It is expected that where children look will not change but that their face tuning will become sharper as they age. These possibilities will be tested by comparing children across di?erent ages and through longitudinal testing of the same children.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.