December 7, 2021
Written by: Marissa Maroni
When you are asked to imagine your favorite food, what do you see? How vivid is the image? Can you imagine your favorite food in a different place? If you struggle to visualize these scenarios it could indicate that you may have aphantasia. Aphantasia is defined as the inability for someone to have mental images or visual imagery. It was first described by Francis Galton in the 1880s when he identified people who lacked the ability to form mental images1. The term aphantasia, meaning a lack of imagination in Greek, was coined later in 20152. Although it has been estimated that approximately 2-5% of people have poor visual imagery, there is still a lot that is unknown about this condition3.
Is Aphantasia just a lack of metacognition?
Ultimately, it is difficult to know what someone’s internal thinking and imagery is like. Many scientists questioned whether individuals who describe lacking mental images have an inability to know that they are visualizing, rather than an inability to visualize. This awareness of one’s thinking is referred to as metacognition. Scientists from the University of South Whales aimed to address whether aphantasia is caused by a lack of metacognition4. To test this, they used a cognitive task called the binocular rival task. In this test, an individual’s right and left eye are presented with different images and the person must choose the image that appears dominant to them meaning bolder or more prominent. Prior studies had found that showing a quick flash of one of the two images prior to the task primed test subjects to choose that image more often in the subsequent binocular rival task. Further, test subjects can be primed by just being told to visualize one of the two images in their head prior to the test, rather than actually being shown the image. These subjects then have a higher likelihood of choosing the mentally-visualized image.
Researchers harnessed this ability to mentally prime subjects to test whether aphantasia is caused by a lack of awareness of mental images. During this study, researchers asked self-reported aphantasics and individuals who did not report difficulties with mental imagery to visualize one of the images in the binocular rival task. They then measured whether subjects were biased to choose this image they had been instructed to visualize. The scientists found that their control group had a higher priming score, indicating that these subjects had a higher chance of choosing the visualized image as the dominant image during the task. Interestingly, for people with aphantasia, there was no evidence of a priming effect. Assuming that this kind of priming relies on subconscious processes, a priming effect would be expected. This suggests that there is not a mental image forming in aphantasia patients that they are simply unaware of, but rather indicate a lack of mental imagery altogether.
Does aphantasia impact other cognitive functions like memory or dreaming?
Visual imagery is important for cognitive functions such as memory and dreaming. Recently, the same researchers from the University of South Whales conducted another study on individuals with aphantasia to investigate if aphantasia is associated with other cognitive impairments5. Using a series of cognitive tests, they found that in addition to visual imagery deficits, people with aphantasia had deficits in imagery of taste, sound, and smell. Further, they had deficits in episodic memory when asked to imagine past or future life events and they reported fewer and less vivid dreams.
The scientists hypothesized that people with aphantasia might be protected from post-traumatic stress disorder (PTSD), as visual imagery is thought to be an important component of this type of disorder, leading to symptoms such as flashback to a traumatic event. However, the researchers found that individuals with aphantasia were not protected from symptoms of PTSD even though they lack mental imagery.
Collectively, there is still a lot that is unknown about aphantasia. However, scientists are finding creative ways to understand what is occurring in someone’s mind. In the future, brain imaging and cognitive tasks could help us to understand if there are differences in brain activity in people who struggle with mental imagery.
1. Galton, F. (1880). Statistics of mental imagery. Mind, 5(19), 301-318.
2. Zeman, A. Z., Dewar, M., & Della Sala, S. (2015). Lives without imagery-Congenital aphantasia.
3. Faw, B. (2009). Conflicting intuitions may be based on differing abilities: Evidence from mental imaging research. Journal of Consciousness Studies, 16(4), 45-68.
4. Keogh, R., & Pearson, J. (2018). The blind mind: No sensory visual imagery in aphantasia. Cortex, 105, 53-60.
5. Dawes, A. J., Keogh, R., Andrillon, T., & Pearson, J. (2020). A cognitive profile of multi-sensory imagery, memory and dreaming in aphantasia. Scientific Reports, 10(1), 1-10.