We report three patients who significantly improved their speed and accuracy reading untrained
words following a two-phase tactile/kinesthetic treatment. What is most striking about these findings is that all three patients were able to do so without overtly using the tactile/kinesthetic strategy
. This improvement is not likely attributable to spontaneous recovery. Spontaneous recovery of letter naming has been reported in the literature, but it tends to happen very acutely, during the first weeks following the stroke (Beeson, Magloire, & Robey, 2005
). Beeson et al. (2005)
reported that their patient demonstrated 100% letter naming by 15 weeks post-onset, and they cited two additional cases in the literature that also fully regained their letter naming during the acute stages of recovery. Our patients were chronic and demonstrated stable letter naming performance over repeated baseline measures. Furthermore, if improvement were due to spontaneous recovery, one would expect their other language impairment, naming (and auditory comprehension in the case of DBR), to also improve. None of the patients demonstrated this.
The patients in the current study had relatively mild letter naming deficits (ranging from 73% to 77% accuracy). Lott et al. (1994)
and Lott and Friedman (1999)
have shown that the tactile-kinesthetic approach also successfully improves word reading in patients who demonstrate more severe letter naming deficits (49% and 62% accuracy, respectively). It remains to be seen whether these more severely impaired patients could progress to reading without overt use of the strategy, as did the more mildly impaired patients in the current study.
One might predict that once letter naming became highly accurate, then letter-by-letter word reading accuracy would follow suit. This was not the case. In order to significantly improve reading without overt use of strategy, all patients required the additional practice in Phase 2 treatment. In fact, Phase 1 was not even sufficient to significantly improve reading with overt use of the strategy. Two of the patients were additionally tested following Phase 1 reading words with overt use of the strategy; neither had improved significantly in this condition either (LDR 40% to 50%, binomial test: p = 1.0; IND 38% to 55%, binomial test: p = .143).
One possible explanation for the improvement seen following Phase 2 is that letter naming became more efficient as a result of being repeatedly practiced. As in the Lott and Friedman (1999)
study, letter naming reached criterion in the first treatment phase, and was then repeatedly practiced in the second training phase. The second phase, however, contained multiple components: additional practice naming letters but also practice reading letter-by-letter at the word level. Results from the additional testing administered to two of the three patients in the current study allow us to disambiguate the contributions of these two components. Both patients were already significantly more accurate and faster reading words following rapid letter naming treatment (Phase 2a). This suggests that repeated practice with letter naming was sufficient to achieve significant improvement; subsequent training at the word level (Phase 2b) was not necessary. It should be noted, however, that this study did not control for the order of training rapid letter naming versus rapid word reading. It has been suggested that the training of complex grammatical structures results in generalization to less complex structures that rely on common processes (Thompson, Shapiro, Kiran and Sobecks, 2003
). Based on this Complexity Account of Treatment Efficacy (CATE) it is possible that the complex, rapid word training phase may have produced the same generalization effects had it been administered prior to the less complex, rapid letter naming treatment phase. Regardless, the data clearly suggest that additional practice beyond the point of initial letter naming mastery is beneficial, and that doing so only within the context of letters can result in significant word reading improvement.
Why should additional practice with letter naming be sufficient to improve word reading? One possible explanation is that it is the result of repeatedly practicing the naming of individual letters. Several speech and language treatment studies have attributed successful outcome to the use of some type of repeated practice, or overlearning, in their paradigm (Dworkin, Abkarian and Johns, 1988
; McNeil, Clayton, Barrett, Schober-Peterson, & Gonzalez-Rothi, 1998
; Wambaugh, Martinez, McNeil & Rogers, 1999
). McNeil et al. (1998)
, referring to the classic work of Schneider and Shiffrin (Schneider, Dumais, & Shiffrin, 1984
; Schneider & Shiffrin, 1977
; Shiffrin & Schneider, 1977
), suggested that additional practice on a newly learned task is necessary before it can reach some basic level of automaticity, even if that task was learned to a high level of accuracy. They further suggested that automaticity may be very beneficial for people with aphasia by freeing up cognitive resources which can then be devoted to other language tasks. In this tactile-kinesthetic treatment, improving the efficiency of the serial letter identification process frees up additional cognitive resources to focus on the other skills needed to read words letter-by-letter, such as retaining all the letters identities and then recognizing the word they spell. Since the additional letter naming practice included naming letters presented within letter strings as well as presented in isolation, an alternative explanation is that improvement may be attributable to practice identifying letters in a sequence rather than simply overlearning individual letter names. To evaluate this alternative hypothesis, one patient, IND, was administered additional testing following practice naming letters individually, but prior to naming letters in strings. Following letter naming in isolation, his accuracy reading untrained words without the strategy had already improved significantly over baseline performance (from 38% to 65%, binomial test: p
= .027). Following practice naming letters in letter strings, his accuracy further improved, though not significantly so (to 80%, binomial test: p
= .18). This pattern suggests that the improvement seen following Phase 2a, at least for patient IND, cannot be wholly attributed to the effects of practice identifying letters in a sequence, but rather that the overlearning of naming letters in isolation was sufficient to significantly improve reading of untrained words without overt use of the trained strategy.
While significant improvement was demonstrated prior to word training, some additional gains were made following the word level training. This further improvement may simply be the result of the additional letter naming practice afforded by letter-by-letter word reading practice, or it may suggest that the additional cognitive components of letter-by-letter reading (e.g. retaining letter identities and recognizing the word they spell) also respond to remediation. The relationship between the patterns of change in letter naming and word reading speed depicted in suggest that the answer is patient specific. After Phase 2a in which only letter naming was trained, all three significantly improved letter naming speed and this generalized to improved word reading speed. After Phase 2b in which word reading was trained, the changes in patient DBR’s and IND’s word reading speed continued to parallel their changes in letter naming speed, although in opposite directions: DBR continued to make significant gains in word reading speed and also in letter naming speed, while IND did not make any further gains in his word reading speed nor in his letter naming speed. These patterns are consistent with the first hypothesis that treatment at the word level simply provides additional practice with letter naming; further improvement in word reading speed depended upon whether or not letter naming speed continued to improve. Patient LDR, however, showed a different pattern. He continued to improve his word reading speed after Phase 2b but not his letter naming speed. This pattern suggests that his improvement in word reading speed was not simply the result of additional practice naming letters, but rather of improving the other cognitive components of letter-by-letter word reading.
It remains unclear exactly how these patients processed orthography after treatment. Kashiwagi and Kashiwagi (1989)
claimed that their patient, although not overtly using kinesthetic information when reading, was activating kinesthetic images. This was based on the finding that their patient made more reading errors when concurrently drawing triangles with his left index finger (requiring a kinesthetic image of a triangle) than when repetitively tapping the finger (not requiring a kinesthetic image). Patients with aphasia, but not pure alexia, did not show this interference. Did our patients also internalize the treatment such that they were activating kinesthetic images when they read visually? Did they regain the ability to recognize letters purely visually? fMRI may help us elucidate how these behavioral changes are instantiated in the brain. For example, Puttemans, Wenderoth, & Swinnen (2005)
demonstrated changes in patterns of neural activation with the automatization of a motor task. All of our patients had pacemakers and therefore were, unfortunately, not magnet compatible. We plan to use imaging when possible with future patients to evaluate how the behavioral outcome of this treatment may be instantiated in the brain. While we can’t speculate on whether or not our patients imaged kinesthetic movements when they read, they did continue to demonstrate length effects in their reading, suggesting that they continued to read in letter-by-letter fashion .
This study has important implications both theoretically and clinically. First, it provides additional evidence on the efficacy of using a tactile-kinesthetic approach to improve letter naming in patients with letter-by-letter reading. Secondly, it demonstrates that learning a tactile/kinesthetic mediating strategy can alter cognitive processing such that words never specifically trained can be read in free vision without overtly using the mediating strategy. While it remains unclear exactly what mechanism underlies this processing shift, the data suggest that an important element in achieving this level of generalization is continuing training beyond the point of initially mastering letter naming accuracy.