A Statistical Test Learning Rate?

First off, I apologize if I am creating a new thread for something that already exists. I used the search option, but didn't find anything that seemed to relate to my question. Though, it's entirely possible that I'm using the wrong search terms.....

I was wondering if someone could recommend an appropriate statistical test based on some results I'd like to look at.

I have data from an experiment were participants were given a S+/S- discrimination for 16 trials. There are two conditions within the task, one easier and one harder, and everyone experienced the same conditions. My graphs show that the rate of learning is different for the two conditions, where participants reach optimal performance faster (i.e., in fewer trials) in the easy condition compared to the hard.

I am looking for an appropriate statistical test to measure the rate of learning for the two conditions.

Maybe it might be also helpful, the data I have collected show proportion correct for trials 1 through 16. So on trial 1, both the easy and hard is around .10. As the trials progress (2,3,4,5,...), proportion correct increases faster in the easy condition, relative to the hard.

Bonus points! I also have two groups, so if there is a statistical test that can compare the rates of learning between the two conditions (within-subjects factor) but also compare how these differ between the two groups of participants (between-subjects factor).

Any help would be greatly appreciated!