This phenomenon is called aphantasia—and it’s a relatively mysterious neurological condition whereby people are unable to visualize things in their heads. Here’s what the little research we have on it has found so far, plus how to find out whether you have it. When someone with aphantasia does try to imagine something, they simply can’t and instead see a void of darkness. Neuroscientist and author of The Source Tara Swart, M.D., Ph.D., explains that aphantasia is complex, and its effect on people can vary. For example, she says it can also manifest as the inability to recognize faces, form visual memories, or imagine something new that you haven’t seen before. It differs from prosopagnosia, the inability to recognize familiar faces, which often happens as the result of a stroke or traumatic brain injury. Swart adds that the condition has “no bearing on intelligence or any other neurological syndrome.” One explanation for why aphantasia might occur has to do with childbirth and brain development, Swart says. “During the process of childbirth, when the brain is very undifferentiated […] babies actually have a series of mini-strokes.” Thanks to neuroplasticity, she explains, a baby’s brain is usually able to adapt and build more neurons in this developmental stage. But in the case of aphantasia, “That tiny little pathway that’s related to visual imagery or visualization just doesn’t work.” Presently, there is no treatment for the condition. But with the proper understanding and tools, people with aphantasia can still thrive. That said, there is a simple and helpful test that can give you a clue into whether you may have it: Close your eyes and try to imagine an apple, seeing it mentally in your mind’s eye. If you can see anything (anything at all—even a blurry outline), you do not have aphantasia. If you see a void of complete darkness, you might have aphantasia. If you want to take a deeper dive into testing your ability to visualize, there is something online called The Vividness of Visual Imagery Questionnaire, Swart adds, which has been found to accurately measure the vividness of your visual imagination. Even if you don’t have full-blown aphantasia, you might find that you don’t visualize in great detail. Swart adds that many people with aphantasia can still have visual memory recall. However, she’s heard of many people with aphantasia report less “rich” dreams, memories, and imagined future scenarios. This indicates that for some people with the condition, aphantasia means you’re deficient in creating imagery in the mind’s eye, but you don’t lack the ability altogether. “The existing literature points to a range of pathological and pharmacological factors that can influence vividness,” reads a 2016 paper in 1Cortex1. “Psychological and psychiatric factors should be taken into account in the assessment of a person complaining of aphantasia.” With that being said, the authors of that study remain doubtful that mental illness plays “a major role among people reporting lifelong aphantasia.” It seems that in most cases, aphantasia is something people have dealt with for most of their life and doesn’t typically have wider implications or associated conditions. It is worth mentioning that additional research has suggested2 that “the potential impact of visual imagery absence on wider cognition remains unknown.” Until the mechanisms behind aphantasia are fully understood, there is no cure for it.