Today, it seems clear that there may be many types of alexithymia. While some might have trouble expressing emotions, others (like Caleb) might not even be conscious of the feelings in the first place. Richard Lane, at the University of Arizona compares it to people who have gone blind after damage to the visual cortex; despite having healthy eyes, they can’t see the images. In the same way, a damaged neural circuit involved in emotional processing might prevent sadness, happiness or anger from bursting into consciousness. (Using the analogy of the Russian doll, their emotions are breaking down at the second shell of feeling – their bodies are reacting normally, but the sensations don’t merge to form an emotional thought or feeling.) “Maybe the emotion gets activated, you even have the bodily responses, but it happens without you being consciously aware of the emotion,” he says.

Along these lines, a few recent fMRI scanning studies have found signs of a more basic perceptual problem in some types of alexithymia. Goerlich-Dobre, for instance, found reduced grey matter in areas of the cingulate cortex serving self-awareness, potentially blocking a conscious representation of the emotions. And André Aleman at the University Medical Centre in Groningen, the Netherlands, detected some deficits in areas associated with attention when alexithymics look at emotionally charged-pictures; it was as if their brains just weren’t registering the feelings. “I think this fits quite well with [Lane’s] theory,” says Aleman – who had initially suspected other causes. “We have to admit they are right.”