In the Leitner system, correctly answered cards are advanced to the next, less frequent box, while incorrectly answered cards return to the first box for more aggressive review and<unk> .<unk>  is an evidence-based learning technique that is usually performed with flashcards. Newly introduced and more difficult flashcards are shown more frequently, while older and less difficult flashcards are shown less frequently in order to exploit the psychological spacing effect. The use of<unk>  has been proven to increase the rate of learning. Although the principle is useful in many contexts,<unk>  is commonly applied in contexts in which a learner must acquire many items and retain them indefinitely in memory. It is, therefore, well suited for the problem of vocabulary acquisition in the course of second-language learning. A number of<unk>  software programs have been developed to aid the learning process. It is also possible to perform<unk>  with flashcards using the Leitner system. Alternative names for<unk>  include<unk>  rehearsal, expanding rehearsal, graduated intervals,<unk>  spacing,<unk>  scheduling,<unk>  retrieval and expanded retrieval.
Spaced repetition
Burst suppression
Out-of-body experience
Adequate stimulus
Prepulse inhibition
Haptic communication
Extensions to the International Phonetic Alphabet
Situational strength