Author:

Keywords:

congenital prosopagnosia, composite effect, face perception

Abstract:

Human bodies exert strong social relevant information, especially in social interactive contexts. Overall, there is consensus that social information cues must be (visually) processed in a fast and efficient manner. However, the exact nature of visually processing the human body is still a matter of debate. In contrast to the human body, overall consensus has been reached for faces; Faces are processed as a whole and evidence for this holistic face processing comes from experimental work but also clinical work, with prosopagnosia case studies as prototypical examples. These patients show face-specific recognition deficits due to the inability to perceive faces as wholesome entities (holistic processing), while general object recognition mechanisms remain intact. While body processing might be intact in acquired prosopagnosia, such a case might not be so trivial in congenital forms of this disorder (CP). CP patients never processed faces holistically in the first place, and this lack of processing might cause a more global processing deficit generalizable to other social stimuli. On the other hand, CP patients might also be better at processing human bodies as these are next in line as reliable recognition cues and CP patients might be better adapted in using such information. In this study we used the composite effect, a paradigm that has been used to detect configural processing mechanisms in bodies and faces. In this paradigm participants are presented (sequentially) with two faces (Experiment 1 and 2) or with two body postures (Experiment 3 and 4). In one set of experiments (1 and 3), they have to decide whether the top halves of the two stimuli are the same; in another set of experiments (2 and 4), the have to decide on the similarity of the right halves of the stimuli. There is interference in task-relevant same trials (top in Experiment 1 and 3; right in Experiment 2 and 4) when the two stimuli differ in the task-irrelevant region (bottom in Experiment 1 and 3; left in Experiment 2 and 4), but only when the body parts are aligned, not when they are misaligned. We show that this effect is modulated by CP. Implications, both for CP and a better understanding of configural processing of social relevant stimuli, are discussed.