Aphantasia is a curious feat of humankind's neurodiversity. Reportedly, people with this condition cannot see any imagery with their mind's eye. Some cases even report that they cannot even audiate sounds within their mind, imagine a world where you cannot get Africa by Toto stuck in your head for weeks at a time, wild, eh?
It is not considered a disability or disorder like ADHD or specific learning disability, most people with this condition don't even realize they have it (people with this condition make up about 2-5% of the general population). Though, mostly congenital, it can be acquired too. Often people acquire it as a result of head trauma or brain surgery, but there are cases of acquisition through heart surgery as well.
The condition is so sneaky that it was first described by Francis Galton during the 1880s. While the condition does not affect creativity, it arguably brings some subtle hardships such as not being able to lay-out a proper perspective for a drawing.
The research team led by Alexei Dawes has made the biggest sample-size study on aphantasia to date. In this study, Dawes found "...that aphantasia isn’t just associated with absent visual imagery, but also with a widespread pattern of changes to other important cognitive processes".
What this implies is rather interesting, turns out people with aphantasia have hardships remembering past, imagining future, and even have vivid dreams.
Another interesting feature of aphantasia is that, while aphantasic participants were not able to visualize a sunset or the beach, many were able tofeel the sand below their feet or audiate the wind hitting their ears and waves crashing ashore. Though 26% of participants reported a wider absence of sensory imagery, including senses taste, smell, emotion (see also alexithymia), touch, and sound.
Lack of dreams
Imagining stuff is voluntary, but what about an involuntary action, say, dreaming? Turns out aphantasiacs experience fewer dreams altogether, and when they do, they are "less vivid and lower in sensory detail" says Pearson - one of the co-authors.
Similarly, aphantasiacs show a significantly reduced ability in recalling details of a past event.
While a professional opinion is required to reach an absolute conclusion, you can find a self-report questionnaire called Vividness of Visual Imagery Questionnaire here.