"Blind imagination" neuroscience press release

For anyone new to the aphantasia discussions: It's a fancy word for not visualizing, or as I've tended to describe it, not having a mind's eye. I don't picture characters or scenes when I read books, for example.

As a rhetoric person and disability studies person, I looked at how we talk about aphantasia, in three parts. (Part one, part two, part three). As a neuroscience student, I wrote about one of the articles (Zeman et al, 2010, the case study) in terms of significance. And yes, some of the results are things I could totally have told you myself. Like the fact that "mental imagery" tests such as rotation (check if two block structures with angles are the same or not) can be done in ways other than rotating an image of the object. I know that because I don't view such images in my head and I'm good at the task. Testing everything is how science works, and trying to figure out what someone is doing rather than just what they aren't doing is still handy. So here it is!

A research team in the UK has shown the potential for dissociation between the experience of visual imagery and performance in tasks typically associated with visual imagery and visual memory in a case study. The patient, a 65 year old retired surveyor referred to as MX, reported the sudden loss of his ability to visualize. However, he retained the ability to complete tasks typically associated with visual imagery and visual memory, including mental rotation tasks.

The authors did a series of tests both on MX and on a group of controls of similar age, IQ, and professional backgrounds. These tests included assessments of general intelligence, memory, executive function, visual perception, subjective vividness of visual imagery, and imagery abilities. MX scored significantly lower than controls on subjective assessments of visual imagery. However, his scores in the other tests were not significantly different from that of controls. In the fMRI experiments, MX showed similar areas of activation to the control participants while viewing images. However, MX showed significantly different activation patterns when asked to generate faces. Rather than activating the posterior visual network, MX showed prefrontal activation in areas associated with many executive tasks.

Further behavioral testing was conducted to test if MX was using alternative cognitive strategies. The researchers gave MX variants of Brook's matrix and verbal tasks, along with mental rotation tasks. Here, MX's performance differed from typical patterns. While typical controls consistently perform better on the spatial Brooks task than on the verbal one, MX performed better on the verbal task. When asked to perform the typically visuo-spatial version of the task with verbal or visuo-spatial interference, MX showed no significant difference in performance between no distractor and visuo-spatial interference. However, his performance was significantly lower with the verbal distractor, again in reverse of the typical performance pattern. On mental rotation tasks, MX showed no impairment in correct performance. However, he consistently required more time than controls and showed a different relationship between angle of rotation and time required from the controls.

Both the behavioral and fMRI testing indicate the use of alternative cognitive strategies in order to perform tasks typically associated with visual imagery. On most tasks, these alternative strategies yield similar levels of accuracy to controls with typical visual imagery abilities. The case of MX provides insight into alternative ways of completing typically visual tasks. His performance indicates that mental imagery is not essential to tasks typically associated with it, making it less clear that mental imagery is the subject of mental imagery tests. It also indicates that reliance on the mind's eye in decision-making as suggested by Kosslyn is not universal. In addition, this case study may provide insight into the cognitive functioning of a small but significant subset of the population who report no mental imagery. Surveys dating back to 1880¹ show a group that report never having experienced mental imagery, alongside documentation of prior cases where imagery is lost. Further study could determine if similar strategies are used by this population, and what cognitive differences, if any, this is associated with.²

1  Galton, Francis. "I.—Statistics of mental imagery." Mind 19 (1880): 301-318.

Also relevant is: Faw, Bill. "Conflicting intuitions may be based on differing abilities: Evidence from mental imaging research." Journal of Consciousness Studies 16.4 (2009): 45-68.

2 Spoiler alert! This happened to some extent in Zeman, Adam, Michaela Dewar, and Sergio Della Sala. "Lives without imagery–Congenital aphantasia." Cortex 3 (2015). This case study got written up in Discover, then some people who have never had subjective mental imagery [like me!]  contacted the authors. Then people saw the follow up, some of whom also contacted the authors. The 2015 letter was actually the first one I found, followed by the two commentaries on it. [They wonder if there may be a connection with faceblindness, or prosopagnosia, which I also have. My brain. It is multiply interesting.]

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