I want you to think of an apple. I bet you thought of a shiny, red, juicy apple, or maybe a green crunchy one. I also bet the image popped into your head instantly, without you even trying. Even if I told you not to think of an apple, your mind wouldn’t resist. The image would still pop up, uninvited! I can also invite you to think of a pink elephant, a sandy beach, a sun that shines… I bet you have your unique little images about all that stuff. This process is known to neuroscientists as mental imagery, and it’s this amazing ability of our mind to «see» images and objects that are not actually present in the external environment. However, some people are entirely missing this ability. No matter how hard they try, an image will not pop into their head. This condition is called aphantasia and it is found in 2% - 4% of the population.

Aphantasia exists on a spectrum: some people may be able to imagine the apple as a less detailed image, or maybe they can see the shape of the apple but with no colour, or others might know that they are seeing the concept of an apple but not the apple itself. The most common questionnaire experts use to assess mental imagery abilities is the Vividness of Visual Imagery Questionnaire (VVIQ). Depending on the participant’s answers, the final score will fall into 1 between 5, ranging from really vivid mental imagery, to complete absence of mental images, as you can see in the image below. 

Composition by Belbury, original image components by Mrr cartman, Caduser2003, Bernt Fransson and IconArchive.com

This phenomenon was first reported by Francis Galton back in 1880, when he attempted to study the statistics of Mental Imagery, and was found with a couple of very confused scientists as to what this term meant and if it even existed. Like these scientists, most of the people who have aphantasia, also called aphantasics, are not aware of their condition, as they assume that this is how all people function and think.

Many theories have been developed to explain this unique phenomenon. Some people are born with hereditary aphantasia, but aphantasia can also be the result of a brain injury or other psychological causes.

One theory suggests that aphantasia results from reduced connectivity. Reduced “communication” between the visual cortex and higher-order brain regions limits the brain’s ability to generate mental images. Another hypothesis points to differences in the excitability of the visual cortex. Some researchers believe that people with aphantasia may have lower activation in this area, preventing vivid mental imagery. Others propose that aphantasia is linked to variations in how the brain retrieves and reconstructs memories, particularly involving the hippocampus. Previous research has shown that there is a link between remembering personal memories with having vivid mental images. It is suggested that the hippocampus, a key brain structure for memory, serves as a mediator between autobiographical memories, related to our personal experiences, and visual imagination.

Supporting this hypothesis, recent research from the University of Bonn shows that those two brain regions, the hippocampus and the occipital lobe are associated with impaired recall of autobiographical personal memories in aphantasics. The researchers asked the participants to recall autobiographical events while they recorded images of their brain using functional magnetic resonance imaging (fMRI). Using data from these images, they found that the hippocampus is less activated in people with aphantasia when recalling autobiographical events. There were also differences observed in the interaction between the hippocampus and the visual cortex, a brain structure responsible for processing visual information in the occipital lobe.

Understanding aphantasia doesn’t just tell us about the absence of mental imagery, it opens up new questions about how we think, imagine, and remember. If mental imagery plays a role in memory, creativity, or even emotions, what does that mean for those who experience the world without it? And if aphantasia exists on a spectrum, what other variations in human cognition are we yet to uncover?

Research in this field is still unfolding, and we’re only scratching the surface of how the brain constructs (or not!) mental images. As scientists dig deeper, we’re excited to see what else this fascinating condition will reveal about the mind’s inner workings.

Author: Theodora Voulgari

References

(1) Marks, D.F. (1973). Visual imagery differences in the recall of pictures. British Journal of Psychology. 64 (1): 17–24. doi:10.1111/j.2044-8295.1973.tb01322.x

(2) Galton, F. (1880). Statistics of mental imagery. Mind, 5(19), 301-318. https://doi.org/10.1093/mind/os-V.19.301

(3) Keogh, R., & Pearson, J. (2018). The blind mind: No sensory visual imagery in aphantasia. Cortex, 105, 53-60. https://doi.org/10.1016/j.cortex.2017.10.012

(4) Greenberg, D. L., & Knowlton, B. J. (2014). The role of visual imagery in autobiographical memory. Memory & cognition, 42, 922-934. https://doi.org/10.3758/s13421-014-0402-5(5) Monzel, M., et al. (2024). Hippocampal-occipital connectivity reflects autobiographical memory deficits in aphantasia. eLife.doi.org/10.7554/eLife.94916.1.