Interesting stuff.

> the Remember–Know paradigm describes two main types of retrieval response, Remember versus Know. Knowledge which is Remembered is typically recollected in close association with related information pertaining to the learning episode. By contrast, knowledge which is Known is recalled, retrieved and applied without any such additional contextual associations and ‘‘thus, is information which is simply based on a certain sense of just knowing or familiarity [. . .].’’ (Noyes & Garland, 2003, p. 415) One important implication is that the Remember type of memory is thus more vulnerable to fading with time, than knowledge which is Known. By implication, it is assumed that knowledge which is Known is indicative of better learning (Conway, Gardiner, Perfect, Anderson, & Cohen, 1997; Herbert & Burt, 2001). In their experiment, Noyes and Garland (2003) found no differences between the two media (paper versus VDT) in terms of study and reading times, and number of correct answers. On the qualitative comprehension measures, however, there was an effect of presentation medium, with Remember frequencies being almost twice that of Know frequencies in the computer group, while Remember and Know response levels were similar in the Paper group. Noyes and Garland conclude that ‘‘characteristics of the computer screen (refresh rate, high levels of contrast and fluctuating luminance) interfere with cognitive processing for long-term memory’’ (2003, p. 420). These findings were replicated in a later study (Garland & Noyes, 2004),

where the medium was either a PDF or a print version.

> There are several possible explanations why, in the present study, subjects in the print condition scored significantly higher on the comprehension tests than those in the screen condition. Considering the length of the stimulus text, and the fact that the computer condition text was in PDF format, the difference in comprehension performance between the print and the computer group could be related to issues of navigation within the document. When reading on screen, scrolling is inevitable unless the text is within the screen size. Scrolling is known to hamper the process of reading, by imposing a spatial instability which may negatively affect the reader’s mental representation of the text and, by implication, comprehension (Baccino, 2004; Eklundh, 1992; Piolat, Roussey, & Thunin, 1997). By presenting the texts as PDFs, we intended to minimize the potentially negative effects of scrolling. However, the scrolling option was not excluded from our material. We have no data showing whether or not, and to what extent, the students in the computer condition used the scrolling option when reading the texts. Hence, it cannot be eliminated that students in the computer condition scrolled during reading, and that this scrolling negatively impacted their comprehension performance

I'd like to see a study where the computer test uses an iPad with a PDF app that does horizontal paging instead of scrolling (which is generally what I do with my non-fiction ebooks).

Honestly, the study is worth reading. There are some other factors they mention that could explain the difference, such as the spatial representation and immediate access to the whole text, physical dimensionality, etc.