Philip Boswood Ballard repeated performed an experiment in the early 1900s on more than ten thousand schoolchildren, documenting their ability to recall a poem. He found that the students' performance actually improved over the first four days or so, and then plateaued (Carey, 2014, paras. 7.62). This effect is observed when the material to be recalled involves imagery, but not for mere nonsense syllables, such as Ebbinghaus used.
Robert and Elizabeth Bjork describe a "new theory of disuse" which separates memory into two quantities: storage strength and retrieval strength (Bjork & Bjork, 1992). The former increases as the memory is used, but does not decrease. The latter decreases over time, and is strengthened by use. It is the behavior of the retrieval strength that is responsible for the spacing effect.
Traditional measures of vocabulary knowledge, such as Wesche and Paribakht's (1996) vocabulary knowledge scale (VKS), probably underestimate "hidden learning", when a word becomes more familiar to the reader, but not enough to count as fully known. A system such as described by Horst (2000, pp. 149–150) may be used to estimate this learning (Cobb, 2007, pp. 39–41).
Swaffar (1985) writes that it is important that the reader of a foreign-language text understand the purpose of the text and the cultural environment. She describes an experiment: two groups read one of two letters describing the marriage of a Hindu and Christian couple, each group (Indian and American) reading the letter in their native language. Both groups made significant misinterpretations, which are attributed to the unfamiliarity of readers with cultural elements.
Landow (2006, pp. 13–22) describes the different types of links that may be used in hypertext, and questions whether there is really any difference between an active reader pausing to perform searches for related material and a system automatically generating links to related material on demand, giving the example of such menus of links generated by Microcosm, or dictionary integration in Intermedia.
Haugeland (1985, pp. 48–52) writes on formal games, such as Chess or tic-tac-toe. In such a game, what counts are (only) the rules and the state of the game. This discussion is working toward a definition of a computer as an "interpreted automatic formal system".