Face inversion superiority in a case of prosopagnosia following congenital brain abnormalities: What can it tell us about the specificity and origin of face-processing mechanisms?

Abstract

In the current study we describe J.M., a 15-year-old boy with a history of congenital brain abnormalities and concomitant visual-processing impairments. J.M.'s most prominent deficit is his impaired face recognition, but formal testing also revealed deficits in other domains of visual processing. One aspect that emerged from J.M.'s visual-processing assessment was a tendency to focus on local features and to rely on them for the encoding and identification of visual stimuli including geometric figures, objects, words, and inverted faces. In spite of this general tendency, he was impaired on tasks requiring the encoding of local features in upright faces. Moreover, his ability to distinguish between features in upright faces was significantly worse than that for inverted faces, the opposite pattern to that typically found in normal participants. What is it that keeps J.M. from applying his otherwise intact feature-based processing to upright faces? As proposed in previous reports of face inversion superiority in individuals with acquired face recognition impairments, we suggest that J.M.'s “inverted-face inversion effect” speaks for a specialized cognitive system that is mandatorily engaged by upright (but not inverted) faces, even when it is impaired and therefore maladaptive. In addition, since J.M. suffered from congenital brain abnormalities affecting the normal development of his face-processing skills, his performance suggests that specialized and mandatorily activated face-processing mechanisms are not entirely experience dependent, and that they can remain modular during development even if they don't function properly and are therefore maladaptive.

Keywords:

• Prosopagnosia
• Face processing
• Innateness
• Domain specificity
• Modularity
• Face inversion effect

Acknowledgments

Thanks to: J.M. and his family, all the control participants in this study, the Children's Hospital at Westmead for referring J.M. to us, and the McMaster Vision Lab for providing us with testing material. The current study was approved by the Ethics Committees of Macquarie University, The Children's Hospital at Westmead, and the New South Wales Department of Education and Training and has therefore been conducted in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki. Informed consent was obtained from all participants.

Notes

¹Recent studies have questioned to which extent the newborns' attention to faces is driven by a more general attention to stimuli with basic visual properties such as top-heaviness and congruency. For a discussion of this debate see Macchi Cassia, Valenza, Simion, and Leo (2008).

²This pattern was no longer evident one year after the deprivation period.

³Congenital hydrocephalus refers to an abnormal accumulation of cerebrospinal fluid (CSF) in the ventricles of the brain, the onset of which is before birth. The resulting elevated intracranial pressure typically causes compression of the brain, often leading to brain damage and other complications such as epilepsy.

⁴Unfortunately, no structural brain scan was available.

⁵Stimuli for this task were obtained from Prof. Michael Tarr's web page: http://titan.cog.brown.edu:8080/TarrLab/stimuli/objects/svlo.zip/view

⁶Stimuli for the Mooney Faces Task and Jane Task were provided by the McMaster Vision Lab. For a detailed description of the stimuli see Mondloch, Le Grand, and Maurer (2003) and Le Grand, Mondloch, Maurer, and Brent (2001), respectively.