Hilary PalménThanks to a nudge from a colleague I've just found this wonderful research paper by Sophie Beier and Kevin Larson in 2010. It evaluates different design characteristics of commonly confused (difficult to identify) letters using multiple different identification tests. the goal being to help design more easily identifiable letters. fabulous!
https://www.researchgate.net/publication/233608849_Design_Improvements_for_Frequently_Misrecognized_Letters. It was uploaded to researchGate (Open access) by Sophie Beier. Awesome!