Face Blindness: Case Studies on Developmental Prosopagnosia BY ELIZABETH (SHUXUAN) LI '25 Cover Image:: Prosopagnosia, otherwise known as face blindness, is characterized by the inability to distinguish faces. If looking at the image, a prosopagnosic would realize that there are faces on the walls but would have extreme difficulty in telling them apart Image Source: Uppertal, 2014
History and overview For humans, the most prominent form of sensory detection has been vision. When interacting with others, humans rely heavily on the visual pathway to obtain information about the content and emotions of the speaker. Under circumstances where communication lacks a visual component, such as phone calls or texting, the brain can easily miss clues about the moods and feelings of those on the other side. Hence, the detection of facial features in others is essential to everyday interaction. In the past century, psychologists’ attention has been drawn to a small but steady stream of cases where an individual’s facial recognition has been impaired since birth in a condition named “developmental prosopagnosia.” One of the first scientists to study prosopagnosia was German neurologist Joachim Bodamer, who coined the name of the condition as “ProsopAgnosie” in German (Bodamer, 1947). In general terms, developmental prosopagnosia (DP) is “the selective degradation of face perception and face memory” since birth in the absence of previous brain trauma (Duchaine & Nakayama, 2006). Distinct from acquired prosopagnosia,
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where a major head injury deprives patients of their ability to distinguish faces, developmental prosopagnosics have never been able to recognize faces as successfully as the average individual. In addition to lowered sensitivity to differences in facial features, some developmental prosopagnosics observe one half of someone's face as morphing (hemi-prosopometamorphopsia) or even displace one person’s face as someone else’s (Almeida et al., 2020; Jonas et al, 2018). Systematically, the criteria for a DP diagnosis require (1) impediments in facial recognition abilities to the extent of impacting one’s daily life in significantly negative ways and (2) lab testing using methods such as the CFMT (Psychology Experiments: Cambridge Face Memory Test, n.d.). This paper first contextualizes developmental prosopagnosia in real life by discussing its consequences on daily functioning; then, it will explore two aspects of face processing that are relevant in understanding the disorder, followed by three notable case studies on DP that each represents different cognitive and neural aspects of the condition.
DARTMOUTH UNDERGRADUATE JOURNAL OF SCIENCE