The role of familiarity and movement in face recognition

Abstract

Research on static faces has found that familiarity has a strong influence on face recognition. To this point, though, few studies have compared familiar and unfamiliar face recognition using moving stimuli. This thesis examined the effects of familiarity and movement on face recognition, to determine whether movement conveys the same benefits for both familiar and unfamiliar faces. There are both empirical and theoretical reasons to suppose that familiar and unfamiliar faces would derive different benefits from movement. In general, studies using familiar faces have found a reliable advantage for moving stimuli, whereas the movement advantage for learning or matching unfamiliar faces is less consistent. Furthermore, a recent model of movement and face recognition (Roark et al., 2003) suggests that familiar faces should benefit from movement in two ways: first, movement may increase the amount of structural information available in a face; second, people may be able to identify someone's characteristic movement patterns. Unfamiliar faces, on the other hand, should primarily benefit from enhanced structural information, with little (if any) role for characteristic movement patterns. This implies that familiarity may result in a quantitative, and possibly qualitative, difference in the movement advantage for face recognition. Alternatively, the apparent differences found between familiar and unfamiliar faces may be purely methodological: studies of movement-based face recognition have often used significantly different tasks and stimuli when testing familiar and unfamiliar faces. This thesis presents nine experiments that assess the role of movement in familiar and unfamiliar faces, with a particular focus on examining whether the difference between familiar and unfamiliar faces is qualitative or quantitative, and on the influence of methodological factors on the movement advantage. Experiments 1 "" 4 assess the role of movement in famous and unfamiliar face matching, and examine methodological factors such as stimulus duration, task, and overlapping movement sequences (Experiments 1 and 2); or the type of stimulus (Experiments 3 and 4). Experiments 5, 6 and 7 investigate whether the movement advantage for famous and unfamiliar faces varies depending on the type of movement (rigid, non-rigid, or both) and whether adding movement cues from the eyes and mouth increases the movement advantage. The final set of experiments (Experiments 8 and 9) examines the effect of two different types of familiarity, using personally familiar and self-faces. Overall, there appears to be little qualitative difference between the movement advantage for familiar and unfamiliar faces, but the size of the movement advantage (i.e., the quantitative effect of familiarity) varies depending on the task. When participants match or sort two faces (Experiments 1-4, 8-9), unfamiliar faces show a larger movement advantage than familiar faces, primarily because static matching of familiar faces is highly accurate. However, when participants sort four faces at once (Experiments 5-7), famous faces show a larger movement advantage than unfamiliar faces. These results are noteworthy for two reasons: they are the first results to suggest that unfamiliar faces may benefit more from movement than familiar faces under some circumstances; and the first to show that the movement advantage for both familiar and unfamiliar faces relies on a combination of structure-from-motion and characteristic movement patterns. Overall, the results point to a flexible use of static and dynamic cues to identity. The relative contribution of static and dynamic cues varies depending on the familiarity of the face, the amount of static information in the stimuli, and the number of comparisons required to complete the task.

Date of Award	2012
Original language	English