Desirable difficulty

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A desirable difficulty is a learning task that requires a considerable but desirable amount of effort, thereby improving long-term performance. The term was first coined by Robert A. Bjork in 1994.[1] As the name suggests, desirable difficulties should be both desirable and difficult. Research suggests that while difficult tasks might slow down learning initially, the long term benefits are greater than with easy tasks.[2] However, to be desirable, the tasks must also be accomplishable.

Many tasks give the illusion of learning because they are too easy. For example, re-reading notes or a textbook is a common learning tactic that has been proven to be less beneficial than using flashcards.[2] A student will feel like he or she is learning when re-reading, but this is partly due to the fact that the words are more familiar rather than that the material is being processed and learned. Flashcards, on the other hand, require the student to actively recall the information. This is a desirable difficulty because it requires more effort and forces the student to do more complex processing. At first, learning with desirable difficulties may take longer and the student may not feel as confident, but over time knowledge will be retained better.[2]


To determine whether a difficulty is desirable, use the following three guidelines:[2]

  1. The processing at encoding should be the same as the processing at retrieval.
  2. The processing at encoding should be the same as the processing during practice.
  3. The task must be able to be accomplished. Too difficult a task may dissuade the learner and prevent full processing.

Research and examples[edit]

Researchers have experimented with various methods of learning. A common theme between the methods that have proven to be most beneficial is that they all present difficulties and challenges to the learner.[3] Compared with traditional easier learning methods, they appear to make learning slower. The traditional easy tasks often show better temporary performance effects, and these are confused for more permanent effects.[4] While this is somewhat counterintuitive, studies show that difficulties are better for increased performance in the long run. The following are examples of training tasks that are desirably difficult.

Retrieval practice[edit]

Also known as the testing effect, retrieval practice uses testing as a training tactic. Performance can be improved by devoting some of the learning period to testing by trying to recall the to-be-learned information. An example of this is flashcards, where a student will try to answer what is on the back of a card based on what is written on the front of a card (i.e. a word on the front and its definition on the back). For best results, feedback is key; the learner should receive feedback on their performance and learn the correct answers.

Delayed feedback[edit]

To improve, students need to receive feedback on their work; feedback could consist of the correct answers, a grade, comments, etc. While feedback is essential, a surprising result found is that delaying feedback is better than receiving immediate feedback[citation needed]. This is contingent on the delayed feedback being guaranteed. Feedback in any form is better than no feedback at all.

Spacing and interleaving[edit]

The spacing effect consists of repetitive studying while ensuring that there is a delay between repetitions. If this delay is created through studying another task or subject, the method is known as interleaving. An example of this is reviewing notes from previous weeks every week up until the final. This will space out the review sessions instead of cramming and increase amount of information that is committed to long term memory.

Combined techniques[edit]

Combining desirably difficult techniques in the right ways can be beneficial. For example, the 3R (Read/Recite/Review) technique involves reading a piece of text, reciting the text without looking, and then reviewing the text again. In one experiment, students who used this task performed better than those who simply reread the text.[2] This method takes advantage of two desirable difficulties. The first is that recalling what is written in the text takes considerably more effort than rereading. The second is that during the review stage, students are actively looking for feedback rather than passively receiving feedback in other ways.

Sans forgetica typeface[edit]

Sans forgetica is a minor version of Helvetica sans-serif intended as a desirable difficulty learning aid for competent readers[5]. However, there is no scientific evidence that sans forgetica has any effects on actual performance.


For students[edit]

Students can easily incorporate these techniques into their everyday studying habits to increase their memory capacity. For example, instead of reading material, testing yourself with flashcards will harness the testing effect. The spacing effect and interleaving can be accomplished by studying multiple subjects, spending time on one then taking a break studying another subject before returning to the original subject. This enforces interleaving by mixing several subjects while also spacing out the studying over different intervals.

For teachers[edit]

Teachers and professors can utilize spacing by including problems on past topics throughout different homework assignments. They can also utilize the test-a-day method to enforce the testing effect, by requiring students to consistently recall information. Delaying feedback on tests and quizzes is also beneficial, but as long as it is not delayed so long that the students do not read the feedback.

One issue with a majority of current research is that it occurs over a short time span such as a few hours to a couple of days; however, teachers and professors are more interested in ensuring the material they teach remains long term. Through the study of people's recollection of high school Spanish words, Harry Bahrick was able to show that a considerable portion of information learned in a particular class is remembered throughout a person's life and is known as permastore.[1][2] Bahrick found that spaced post-study sessions promoted permastore for Spanish vocabulary, and likewise, Landauer and Ainslie found that the testing effect increased scores on the information over a year later.[2] The long term effect over decades is still unknown and being researched.


  1. ^ a b Bjork, R.A. (1994). "Institutional Impediments to Effective Training". Learning, remembering, believing: Enhancing human performance.
  2. ^ a b c d e f g Marsh, E. J.; Butler, A. C. (2014). Memory in educational settings. Chapter in D. Reisberg (Ed.) Oxford Handbook of Cognitive Psychology. pp. 299–317.
  3. ^ Bjork, R. A. (1994). Memory and metamemory considerations in the training of human beings. In J. Metcalfe and A. Shimamura (Eds.), Metacognition: Knowing about knowing. pp. 185–205.
  4. ^ Bjork, Robert A.; Schmidt, Richard A. (1992). "New Conceptualizations of Practice: Common Principles in Three Paradigms Suggest New Concepts for Training". American Psychological Society.
  5. ^ RMIT News release 2018/10/03: Sans Forgetica: new typeface designed to help students study