Here's a test. In your head, imagine a red apple. Try to really picture it — its shape, its size, its color. What do you see? Some people get a very clear image of an apple in their mind. They can picture its contours and the length of the stem. Others see an apple that's a little blurry, while others don't see anything at all. If you're someone who sees nothing at all, you could have aphantasia ("a-fan-TAY-zee-uh"). According to the Cleveland Clinic, this means you "don't have visual imagination," so you can't picture things in your mind. It adds that it's "not a disability or medical condition." Experts are still researching aphantasia, but they think that it may affect between 2% and 4% of people. Aphantasia is linked to memory, but it doesn't mean a person's memory is any worse. People who have it might recall things like what a person was wearing, for example, as facts rather than images. However, it's not the same as face blindness. People with aphantasia may be able to recall a person's facial features, or the shape of an apple, but they just won't picture these things in their mind. Some people don't even realize they have it, but it's slowly becoming better known. It didn't even have a name until 2015, although it has been recognized for far longer than that. The Aphantasia Network works to provide a place for people with aphantasia to discuss their experiences. It says that visual aphantasia is most common, but some people may not be able to imagine other senses, including sounds, smells, or tastes. It's not yet clear why any of this happens, although it has been suggested that some people are born with it, while others might develop it in time, perhaps after an injury. There is a lot more research still to be done!