Some letters were found to be more often confused with other letters and these letters were deemed to share similar features E G, B and P were often confused whereas B and X weren't so you'd be flashing either a series sequence of letters up, some of which shared features, some of which didn't, or we thought shared features, and then we saw whether they were confused or not, and this was taken to support the idea that features were extracted from the input, or that's how we constructed the letters or characters that we were perceiving.