Interesting. I’m helping my son with some remedial work and this sounds like what is called the “frustration level” - 85-90% accuracy, more than one mistake in every ten words. The “instructional level” - reading to improve the skill of reading - is a bit lower at 90-95%, less than one mistake in every ten words. Computers certainly don’t experience frustration, and I don’t know if animals would in the studies mentioned - but in kids, it’s associated with giving up on a skill and taking a dislike to the whole thing. So there would have to be some investigation into whether working at this zone of optimal learning actually produced optimal outcomes in people.