Think About The Following Scenarios.
- Loud or unexpected noises
- The smell of someone’s perfume/after-shave
How do they make you feel?
We all differ in how incoming sensory information from the outside world makes us feel. Some of us have a comfortable tolerance for the sensory situations listed above, whereas others would find them overwhelming. This experience is known as sensory sensitivity. People tend to experience sensory sensitivity across the senses (taste, touch, smell, etc.), ranging from hyper-sensitivity to hypo-sensitivity (Robertson & Simmons, 2013). We can think of this as over- and under-reactivity, respectively. For example, someone who is visually hyper-sensitive might actively avoid bright lights. Conversely, someone who is visually hypo-sensitive might be unaware or unresponsive to bright lights, and actively seek additional stimulation (e.g., flicking fingers in front of their eyes). Hyper- and hypo- sensitivities tend to be experienced within the same individuals, either across senses (e.g., avoiding bright lights, but seeking out odours) or within the same sense (e.g., disliking loud noises, but playing the same song on repeat).
As well as differing in our responses to incoming sensory information from the outside world, we also differ in the vividness of imaged sensory information, or in other words, our mental imagery. For some people, mental imagery is exceptionally strong and nearly as vivid as real-life perception, whereas for others it is virtually or completely absent, an experience known as aphantasia (Zeman, Dewar, & Della Sala, 2015). Our recent paper, published in Perception, investigated whether how we image sensory information is linked to how we experience or perceive sensory information in the real world. In other words, are mental imagery and sensory sensitivity linked?
What's The Link Between Mental Imagery And Sensory Sensitivity?
In our study we first set out to investigate whether people with aphantasia tend to have lower imagery across the senses (not just in the visual domain). If so, we could compare levels of sensory sensitivities in people with and without aphantasia to answer questions about the link between mental imagery and sensory sensitivity.
We found that aphantasics tend to report lower levels of imagery across the senses (taste, touch, sound, taste, bodily sensation, feeling) compared to people with visual imagery, and these imagery weaknesses are often severe enough to be considered ‘aphantasia-like’ (i.e., absent or dim/vague). These findings show that people with aphantasia may often experience weak imagery across multiple senses (not just in the visual domain). Our article proposes a new term —dysikonesia—to characterise a broader phenotype for weak or absent imagery across multiple senses. In this context, visual aphantasia (weak visual imagery) is one subtype of dysikonesia (Dance et al., 2021).
Editor's note: Aphantasia Network refers to the experience of absent imagery across senses as multi-sensory aphantasia. If you cannot create mental representations of any senses, visual or otherwise, then you might experience multi-sensory aphantasia. Next, we found that people with aphantasia also reported lower levels of sensory sensitivity, including fewer hyper- and hypo-sensitivities. This means that aphantasics were less likely to find bright lights glaring and less likely to be under-responsive to bright lights, respectively. When we examined each of the senses individually, aphantasics reported lower sensory sensitivity across nearly all of the senses tested. The only sense in which aphantasics reported the same level of sensory sensitivity as people with visual imagery was in the auditory (sound) domain.
These results show for the first time that mental imagery and sensory sensitivity are linked: the vividness of our mental imagery seems to be linked to the level of sensory sensitivity we experience (i.e., lower imagery is linked to lower sensory sensitivity).
Mean hyper- and hypo-sensitivity scores (with 95% confidence intervals) in aphantasics and controls, using the Glasgow Sensory Questionnaire (Higher scores indicate higher levels of sensory sensitivity; Robertson & Simmons, 2013). Note. ** uncorrected p <.01, *** p <.001. Measuring Sensory Sensitivity Using The Pattern Glare Task
To provide further evidence for the link between imagery and sensory sensitivity, we gave a new group of participants a behavioural measure of sensory sensitivity known as a pattern glare task (Ward et al., 2017).
In this task, three types of images (also known as gratings), made up of striped parallel lines, were shown to participants. Importantly, two of the gratings were designed to elicit visual sensitivity (medium-and high-spatial frequency gratings). We measured sensory sensitivity by examining the level of visual discomfort and the number of visual effects (e.g., shimmering, flashing) participants experienced while viewing the gratings.
We found that aphantasics experienced fewer sensory sensitivities than people with visual imagery. Specifically, aphantasics reported less visual discomfort in response to the high spatial frequency grating and fewer visual effects in response to the high- and medium-spatial frequency gratings. This shows that aphantasics were less sensitive to these irritable visual gratings than people with visual imagery, providing further support for imagery and sensitivity being linked.
Example of the Pattern Glare Task (for reader comfort our example here uses a low spatial frequency grating, not designed to elicit sensory sensitivity). In each trial, the grating was presented for 5 seconds, followed by questions about visual discomfort and visual effects. Less Sensory Overwhelm in Aphantasia: A Potential Advantage?
Overall, our study shows that the vividness of mental imagery predicts levels of sensory sensitivity: people with aphantasia not only report weaknesses in imagery across multiple senses (rather than vision alone), but they also experience lower sensory sensitivities. These findings, therefore, suggest that people with aphantasia – on average – might be less overwhelmed by the sensory world compared to people with visual imagery (Dance, Ward, & Simner, 2021).
What's Next?
Our research at The Imagery Lab at The University of Sussex investigates how aphantasia influences numerous sensory, perceptual, and cognitive processes. For example, we examine how aphantasia affects sensory sensitivity, face perception, thinking styles, bodily sensation/feeling, and worry/anxiety, and also how aphantasia intersects with other neurodevelopmental traits such as synaesthesia and autism spectrum conditions. If you’d like to hear about opportunities to participate in our research, all you need to do is fill in this short questionnaire about you and your mental imagery. And if you have any questions, please feel welcome to contact us ([email protected]). 
