1% of the population experience aphantasia, or mind-blindness, which is an inability to visualize concepts or thoughts in their imagination. Researchers investigate this phenomenon and offer explanations as to how this may occur.
People who experience visual imagination have pupillary responses that optimize the amount of light hitting the retina and change in response to imagined items. This pupillary response does not occur in those with aphantasia.
People with hyperphantasia, the ability to visualize vividly, have stronger connections between their visual brain network and decision-making networks. By contrast, those with aphantasia, an inability to visualize, have weaker connections between the brain regions.