Considering the distinction proposed by Harm and Seidenberg (1999), we suppose that the phonological dyslexics, the most prevalent group among dyslexics, are likely to have a deficit in successive processing, whereas the delayed dyslexics are likely to have a mixed deficit in some of the other processes as well. This explanation may be only a partial one; its object is to show the relevance of PASS processes.
An issue that requires further research is delineating the nature of garden-variety dyslexia. The true garden-variety dyslexics who are poor readers in spite of adequate instruction, environmental conditions, and normal emotional characteristics may have a variety of processing deficits, rather than a specific deficit as our previous research indicated (Das, Mensink, and Mishra, 1990).
Both kinds of dyslexics are poor in decoding pseudo-words, although they might have partially overcome their inability to read real words. A recent study (Pugh et al., 2000) of adult dyslexics without neurological impairment shows connections within the brain areas activated during reading to be different between dyslexics and nondyslexics; the implication of its results are significant to Luria’s relevance. Consider the following neuropsychological aspects.
The pathways in the brain that are initiated by seeing a word have been known for some years (Patton, Sundsten, Grill, and Swanson, 1976). Visual reception activates the lateral geniculate nucleus in the thalamus, and travels to the primary visual area, and then on to a higher order visual area. It connects to the angular gyrus, which is the tertiary association area of the parietal-occipital-temporal region, one of the overlapping zones (Luria, 1973).
According to Patton et al. (1976), the sequence continues, activating Wernicke’s area, then Broca’s, and, finally, the facial area of the motor cortex, which results in the articulation of the word. A recent article by Pugh et al. (2000) identifies the tertiary area, mainly in the angular gyrus, to be the hub of word processing. However, their report does not examine the sequence of activity as the old research of Patton et al. (1976) did.
Nevertheless, it concludes from functional Magnetic Resonance Imaging (fMRI) that the activation at the site of the angular gyrus had strong connections with the visual association area and Wernicke’s area, during the tasks that required phonological coding. The tasks involved distinguishing between uppercase and lowercase consonant strings, and between two consonants that rhyme (example of tasks that have low demand on phonological coding).
Two other high phonologically demanding tasks were also given to the dyslexic adults. These required the individuals to distinguish between two pseudo-words that do or do not rhyme, and between two real words that may or may not have the same meaning. The dyslexic adults did not show activation of the angular gyrus while doing the latter two tasks (Pugh et al., 2000). One obvious comment is that those persons with dyslexia were unable to carry out phonological coding. If this is the case, the results confirm that the brain images correspond to what is known behaviorally.
An important conclusion from this new research is that among people with dyslexia, intact activation pathways are preserved and used when phonological processing is within the individual’s ability. There is no sign of a global destruction of these functional connections. The connections can develop if appropriate remediation or intervention programs are instituted early during the developmental period. Remedial methods to enhance reading had focused on enhancing the two PASS processes, namely, successive and simultaneous processing.
This is the PREP program that has been effective in strengthening word decoding (Das, 1999; Das, Naglieri, and Kirby, 1994). However, proper experiments using an “aptitude by treatment interaction” for specific kinds of dyslexics (for example, true dyslexics vs garden variety, phonological vs naming speed deficit, delayed/surface vs phonological dyslexic, successive vs non-successive) are yet to be carried out. Then, we may have clearer guidance for specific remediation for dyslexia.
The Relevance of Luria
We can say, after this brief review on the applications of Luria’s notions of the functional division of the brain and their elaboration in PASS theory and CAS, that Luria is still relevant. Dyslexia as a separate and distinct syndrome can be limited to difficulties mainly in successive processing among beginning readers, and in the planning and allocation of attentional resources as children learn strategies for using orthography in writing and composition.
A plea for diagnosing dyslexia beyond word recognition and pseudo-word reading accuracy and speed is inherent in recent literature as we move into studying adult dyslexics, some of whom are fully compensated and have mastered word reading. If we are looking for cognitive markers, the PASS theory, we may say, has been helpful and should be elaborated. Even in delineating brain locations for dyslexia, Luria’s broad functional organizations are relevant; the more active areas among normal readers were in the temporal area, and the area of overlap between occipital and temporal regions.
The frontotemporal region was found to be involved in making decisions between pseudo-words and real words amongst readers of English, whereas with Italians reading Italian (more transparent orthography), the brain activation was in the left superior temporal regions (Paulesu et al., 2001). Perhaps the English readers are not sure how to read a pseudo-word until they can decide that it is not one of the irregular words, of which there are many in the language.
The Lurian approach also guides remediation by first determining whether an individual child with poor reading has the telltale deficit in his/her PASS cognitive profile. If there is no significant disparity between the four PASS processes, the cause of poor reading performance may lie in cultural conditions, or personality and motivational aspects. In a recent clinical case, an 8-year-old girl showed poor reading and very poor numerical knowledge, and yet had average scores across the four PASS processes. Lack of motivation to continue with tasks when they increased in difficulty, poor instruction, and unconditionally rewarding grandparents, who were bringing up the girl, were discovered as the main explanations for her poor performance.
Improvement in motivation as well as strengthening her reading can be attempted through manipulating PREP tasks. In contrast, another clinical case of a poor reader who was significantly poor in planning but with a high performance on simultaneous and low successive processing would receive a kind of remedial program which trained the child in planning and successive processes. PREP can be manipulated to focus on one or the other process (Das, 1999). Thus, the neo-Lurian approach enables us to measure and diagnose strengths and weaknesses in cognitive processes that characterize poor readers and dyslexics; it also prescribes remediation. Much remains to be done in exploring unexplained reading disability; with regard to PASS, new discoveries in brain activities will compel us to expand and revise Luria’s notions, especially about planning and successive processes.