The Effects of Word Completion and Word Prediction on Typing Rates Using On-Screen Keyboards

Abstract

Word prediction is often recommended by therapists as a means to improve typing speed for clients with physical limitations. Although literature suggests that word prediction does have an effect on writing proficiency, increased speed is not one of its benefits when used with a standard keyboard. One reason given for the failure of word prediction to accelerate typing is that the user must look away from any source document to scan the prediction list during typing. Looking away from the source document may slow the typist more than any acceleration offered by word prediction. For input methods that already require the typist to look away from the copy, this effect might be irrelevant. The focus of this research was to determine whether word completion or word prediction programs would increase typing speed when used with an input method (an on-screen keyboard) that also requires looking away from the source document. Ten people, five men and five women, aged 20 to 38 years, participated in this study. The study used a single-subject, successive intervention design to test typing speed and accuracy using an on-screen keyboard with integrated word prediction software. Seven participants had their fastest typing speed with word prediction. Two participants had their fastest typing speed with word completion. Only one participant demonstrated no improvement in speed when using these two programs. Overall, these results show that the use of word prediction and word completion may assist on-screen keyboard users to improve typing speed.

The effects of word prediction on communication rate for AAC

“…This increase in cognitive load is consistent with our previous findings as well as other researchers [14,16,8,1]. The decrease in input rate due to word prediction is explained by an increasing reliance on the prediction system.…”

“…This method relies on statistics generated from a training corpus -in our case the Switchboard Corpus, which consisted of approximately 2.6 million words. 1 Thus the probability of a particular word being predicted depends on the number of times in the training corpus that that word followed the two words the user has just typed.…”

“…Several researchers' experiments [16,8,1], however, indicate that despite potentially lowering the amount of keystrokes that a user is required to enter to produce a goal word, that gain is not enough to offset the additional cognitive and physical load of using a word prediction system. This load includes such things as focus of attention shifts from the keyboard to the predicted word list, the scanning of the list, deciding whether the desired word appears in the list, and activating the necessary keys to select the desired word when it appears.…”

Effect of dynamic keyboard and word-prediction systems on text input speed in persons with functional tetraplegia

“…Closer examination of the literature suggests that the different effects of word prediction found may be related to the user population and/or the type of system it is coupled with. Studies in nondisabled subjects have found improvements of approximately 3 wpm when using word prediction with on-screen keyboards but not with standard keyboards [22,34]. Word prediction did not, however, appear to be effective in nondisabled subjects using a scanning system [24].…”

Automatic acquisition of grammatical types for nouns

“…Although word prediction is used in AAC devices, researchers have questioned whether it actually increases communication rate (Venkatagiri, 1993;Koester and Levine, 1997;Anson et al, 2004). These works note the additional cognitive demands and cost of using word prediction in conjunction with a letter-by-letter interface, such as the need to shift the focus of attention to the prediction list, the time to scan the prediction list, and the cognitive effort required for making decisions about the predicted words.…”