Aphantasia : a weird lack of mental imagery

Sounds like the name of a ghostly Disney princess but actually it's much more interesting than that :

The former president of Pixar and Walt Disney Animation Studios says he has a "blind mind's eye". Most people can close their eyes and conjure up images inside their head such as counting sheep or imagining the face of a loved one. But Ed Catmull, 74, has the condition aphantasia, in which people cannot visualise mental images at all.

I don't need to close my eyes - is that normal ?

Eventually Ed realised he was not alone and that, perhaps counter-intuitively, some of the greatest talents in animation could not visualise either. Oscar-winner Glen Keane, who created Ariel (The Little Mermaid), also has no visual imagery. Ed told the BBC: "He is truly extraordinary, he's one of the best animators in the history of hand-drawn animation. "[And] he said that he could never visualise either."

The homework also revealed stark differences between two artists and good friends of Ed's who had worked on Frozen. One can see an entire movie in his head and play it backwards and forwards and never needs to see a movie twice because he can visualise it. The other cannot see anything at all.

Okay, I can't do that.

He added: "People had conflated visualisation with creativity and imagination and one of the messages is, 'they're not the same thing... you would think if a person could visualise, they're more likely to be able to draw. [But] If you open your eyes and you take out a pencil and pad, how many people can draw what they see? The answer is a very small number, so if you can't draw what is in front of you then why would we expect that you would be able to draw what you visualise?"

And very few people can draw something as common as a banknote from memory. To some extent mental images could be the brain providing a sense of the experience of visualising something without providing the visual cues themselves, as in the cases where impossible occurrences in dreams seem completely normal. We could be, in effect, imagining that we're seeing all the details but really we're not, a sort of internal blindsight (where the brain receives visual information and can produce accurate responses to it but the conscious mind is unaware of it). So that would mean :

• Hallucinations are when you mistake your internal visualisation for external perception.
• Blindsight is your brain forgetting to create the internal visualisation stage - you perceive things, but not in the usual way.
• Internal hallucinations are when your brain tells you you're seeing something in your mind's eye but actually you're not.
• Internal blindsight would be when you hallucinate that you're having a hallucination, that is, you may think you're not seeing something internally but actually you are (hence the surprising drawing skills).

How on Earth you would know if someone is really able to see something internally versus them just thinking that they can (they might be shite at drawing), I have no idea. All I know is that if you can't ever be sure that what you perceive is real or external or internal or you brain fooling you into confusing these states, then defining knowledge is clearly flippin' complicated.

My head hurts.

'My mind's eye is blind' - ex-Pixar chief

The former president of Pixar and Walt Disney Animation Studios says he has a "blind mind's eye". Most people can close their eyes and conjure up images inside their head such as counting sheep or imagining the face of a loved one.