At this point you're probably thinking, "If only we had high-resolution brain scans of dyslexics performing tasks that involve global visual-spatial processing, then we'd have indisputable evidence of a dyslexic advantage!"

Which do you want first: the good news or the bad news?

The good news is that Diehl et. al. stuck a bunch of people with dyslexia in an fMRI machine and quizzed them with von Károlyi's Impossible Figures , and they did see marked differences between dyslexic and typical brains.

The bad news is that the results still weren't 100% conclusive.

Their findings were consistent with von Károlyi's results in that the dyslexic group was slightly faster on some tests of visual-spatial ability, namely the Impossible Figures test and a test of mental rotation abilities. But, because of course they were, the dyslexic group was only faster when tested outside of the fMRI machine.

Also, the evidence with regards to von Károlyi's theory re: global vs. local processing was mixed: the dyslexics were faster to recognize Impossible Figures, but no faster on the other test of global spatial ability. However, it's difficult to draw any conclusions from this second test because it required the subject to recognize a target letter which is itself composed of smaller letters, like this letter "H" which is composed of the letter "S":

SSS SSS SSS SSS SSS SSS SSS SSS SSSSSSSSSSSS SSSSSSSSSSSS SSS SSS SSS SSS SSS SSS SSS SSS

I don't mean to go full, arm-chair, experimental psychologist, but did no one that reviewed the design of this experiment notice a potential issue? Like the fact that their test of visual-spatial ability involves the alphabet? For a group whose membership criteria is essentially, "Has trouble with the alphabet?"

To their credit, the authors do acknowledge this shortcoming in their discussion of the results. And despite these frustrations, the fMRI data was revealing.

In neuro-typical brains, the Impossible Figures caused the brain to light up with activity, whereas printed text barely provoked a response at all. Relative to the neuro-typical group, the dyslexic brains were less stimulated by the Impossible Figures but significantly more stimulated by the text. In other words, the dyslexic group had to work harder than the neurotypical group to process text, but less hard to process the Impossible Figures.

Not only was the overall level of brain activity different between the two groups - the location of the activity differed, too. In neuro-typical subjects, text caused the left-hemisphere to light up, whereas the Impossible Figures predominantly activated the right-hemisphere. But there was little differentiation in the dyslexic brains: both the left and right hemispheres stayed active, regardless of the task.

The authors concluded that there is probably some trade-off between language processing and spatial processing, and that faster response times for a given task (i.e., reading vs. visual-spatial processing) are correlated with more efficient neural circuitry.

If there is a trade-off between language and spatial processing, then this raises an interesting question: are dyslexics born better at spatial processing? Or does the process of learning to read reorganize the brain at the expense of spatial processing? That is, does becoming a better reader make you worse at spatial visualization?

Unsurprisingly, the authors conclude that answering this question will require further study. If I have learned one thing from reading all of these psych papers, it's that the only thing that psychologists can ever be sure of is that, while their results are promising, nothing is settled and everything warrants further study.

As for me, I've had enough studies: I'm ready to answer the question that started this whole investigation: yes, Muhammad Ali probably had some atypical neuro-circuitry in his right-hemisphere that made him slightly better-than-average at dodging punches.

I'm still confused by something, though: what about Einstein and all of the dyslexic super-geniuses? Surely a small advantage in global visual-spatial processing can't account for what seems to be a massive overrepresentation of dyslexics in the Who's Who list of modern, Western history?

Ok, I lied. We need more studies.