The boy, known as J.M., was born with hydrocephalus (too much cerebrospinal fluid in the brain) and epilepsy, and among his impairments he’s always had a deficit processing faces – a condition known as prosopagnosia.

Schmalzl’s team had J.M. complete a wide-ranging battery of neuropsychological tests and a key pattern to emerge was his bias towards local processing at the expense of global processing. For example, he could identify line drawings of objects when local detail was visible, but he failed when he was forced to rely on silhouettes.

When it came to faces, J.M. was generally impaired as the researchers expected. For example, he struggled to recognise photos of people he knew. However, with specific facial features like noses and mouths, some strange patterns of performance emerged. Consistent with his local-processing bias, J.M. could distinguish between various noses and mouths when they were shown in isolation. He could also do this when they were embedded in inverted faces, yet crucially, and somewhat bizarrely, he couldn’t distinguish between facial features in upright faces.

This inverted face-inversion effect is the opposite of what you’d expect in a healthy person. The researchers aren’t entirely sure what’s going on but they think the case may be a rare example of a faulty face-processing module being activated automatically by the sight of an upright face, thus hindering J.M.’s ability to process the local facial features. This is very much an argument from the camp that sees face-processing as a unique, innate ability. They’re saying it’s possible that J.M.’s innate face processing module still has some uses – for example, it may aid the perception of eye gaze or speech perception – but that in other situations it’s dysfunction actually impairs performance.
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