Similarly, when we discuss evidence for spaced practice compared to massed practice, we see the same pattern. The dirty secret that I share with students is that cramming works, but only in the short-term. Massed practice leads to higher performance on immediate tests of memory, but lower performance on delayed tests compared to spaced practice (4). This time the effect is attributed to the difference in strategies employed when retrieving information from short-term versus long-term memory. In the case of massed practice you don’t have to engage in effortful retrieval from long-term memory. You know the answer because you just saw it recently. However, when practice is spaced you don’t have ease of access from short-term memory so you have to engage in more effortful retrieval from long-term memory.
Finally, we see the same pattern when we examine the effects for retrieval practice compared to re-reading. Re-reading a passage leads to greater memory for that passage compared to repeated retrieval, but only if the test is immediate. After a delay the benefits of re-reading drop off substantially, and retrieval practice emerges as a powerful learning strategy (5). The exact mechanism, or cognitive process, that leads to the benefit of the more difficult strategy may vary somewhat between interleaving, spacing, and retrieval practice, but the overall pattern is the same. The easier condition may lead to higher initial performance, but harder condition leads to better learning.
Now, before we get carried away with the idea that difficulty is always good, it is important to note that this only works if the difficulty is within reason. If the task is too challenging then that can hinder learning performance. This is another theme within education and cognitive research: learning should be just challenging enough, but not too challenging. Much like porridge, it needs to be just right. There are several names for this. In Education, Vygotsky described this as the Zone of Proximal Development (6). In cognitive psychology we discuss desirable difficulties (7).
While we have discussed the downside of ease, and the need or desire for difficulty, for at least a hundred years since Vygotsky, the new conversation around AI assistance in learning has thrown difficulty into sharp relief. There were easier options before, but AI assistance is MUCH easier than we could have achieved without. It’s forcing a broader conversation about what, exactly, we want. What is the point of homework? Is it to do get good grades, or is it to practice and learn? What is the point of engaging in any task, for that matter? Is it to get it done or is it for the sake of the task? In more modern parlance, I’ve seen broader discussion of the concept of “friction-maxxing”, intentionally seeking out the more challenging option in daily life. As a Hoosier, I feel compelled to point out that this idea that we don’t want life to be too easy is something the Kurt Vonnegut remarked on:
“I work at home, and if I wanted to, I could have a computer right by my bed, and I’d never have to leave it. But I use a typewriter, and afterward I mark up the pages with a pencil. Then I call up this woman named Carol out in Woodstock and say, “Are you still doing typing?” Sure she is, and her husband is trying to track bluebirds out there and not having much luck, and so we chitchat back and forth, and I say, “Okay, I’ll send you the pages.”
Then I go down the steps and my wife calls, “Where are you going?” “Well,” I say, “I’m going to buy an envelope.” And she says, “You’re not a poor man. Why don’t you buy a thousand envelopes? They’ll deliver them, and you can put them in the closet.” And I say, “Hush.”
So I go to this newsstand across the street where they sell magazines and lottery tickets and stationery. I have to get in line because there are people buying candy and all that sort of thing, and I talk to them. The woman behind the counter has a jewel between her eyes, and when it’s my turn, I ask her if there have been any big winners lately.
I get my envelope and seal it up and go to the postal convenience center down the block at the corner of Forty-seventh Street and Second Avenue, where I’m secretly in love with the woman behind the counter. I keep absolutely poker-faced; I never let her know how I feel about her. One time I had my pocket picked in there and got to meet a cop and tell him about it.
Anyway, I address the envelope to Carol in Woodstock. I stamp the envelope and mail it in a mailbox in front of the post office, and I go home.
And I’ve had a hell of a good time. I tell you, we are here on Earth to fart around, and don’t let anybody tell you any different.”
Stromberg, D., Lei, V., & Wu, Y. (2026). The Generative AI Learning Penalty: Evidence from Chinese Secondary Education, preprint. http://dx.doi.org/10.2139/ssrn.6868618
Liu, G., Christian, B., Dumbalska, T., Bakker, M. A., & Dubey, R. (2026). AI Assistance Reduces Persistence and Hurts Independent Performance. https://ai-project-website.github.io/AI-assistance-reduces-persistence/
Taylor, K., & Rohrer, D. (2010). The effects of interleaved practice. Applied Cognitive Psychology, 24(6), 837–848. https://doi.org/10.1002/acp.1598
Rawson, K. A., & Kintsch, W. (2005). Rereading Effects Depend on Time of Test. Journal of Educational Psychology, 97(1), 70–80. https://doi.org/10.1037/0022-0663.97.1.70
Roediger, H. L. III, & Karpicke, J. D. (2006). The power of testing memory: Basic research and implications for educational practice. Perspectives on Psychological Science, 1(3), 181–210. https://doi.org/10.1111/j.1745-6916.2006.00012.x
Eun, B. (2019). The zone of proximal development as an overarching concept: A framework for synthesizing Vygotsky’s theories. Educational Philosophy and Theory, 51(1), 18–30. https://doi.org/10.1080/00131857.2017.1421941
Bjork, E. L., & Bjork, R. A. (2011). Making things hard on yourself, but in a good way: Creating desirable difficulties to enhance learning. In M. A. Gernsbacher, R. W. Pew, L. M. Hough, & J. R. Pomerantz (Eds.), Psychology and the real world: Essays illustrating fundamental contributions to society (pp. 56–64). Worth Publishers.
