The concept of “desirable difficulties” was developed by Robert Bjork of UCLA. In his research he noticed various kinds of experimental phenomena which indicated the emergence of 2 predominant patterns in learning .
- Conditions of instruction or practice (learning) that make performance improve rapidly often fail to support long term retention and transfer. Whereas,
- Conditions of instruction or practice(learning) that appear to create difficulties for the learner, slowing the rate of apparent learning, often optimizes long term retention and transfer.
The first one accelerate the learning(Or speeds up learning), the second one slows down learning by introducing difficulties which benefits long term retention and transfer.