So no only were typists not touch typing, they couldn't see what they were typing.
Too many variables are changed between the two tests.
A) writers can see whole words vs no visual feedback B) writers use their natural writing technique (2 or 3 fingers?) vs 1.
It'd be interesting to test typing with a single hand (using words that can be entirely touch typed with one hand)
I'm surprised the choose not to gather that data.
https://repository.lsu.edu/cgi/viewcontent.cgi?article=2306&...
Is interesting in that it shows the opposite effect: improved recall. It also measured velocity/speed of response. Which shows writing was faster.
Another idea for a test: writing without ink.