Another ongoing longitudinal study exemplifies the usefulness of the distal PASS processes in predicting reading difficulty (Papadopoulus, Parrila, and Kirby, 1998). PASS processing tasks, together with several phonological coding tasks, were administered to 90 kindergarten children identified by their teachers as being at risk for early reading problems. Two reading tasks (word attack and word identification) were administered a year later in Grade 1, when children were exposed to reading instruction.
Results showed that performance on both successive processing and phonological tasks at the kindergarten class correlated significantly with reading skills one year later. We note that the group of high-risk children did not include exclusively dyslexic children, rather it was a mixed group designated by their teachers. Some of the high-risk children turned out to have normal reading scores (that is, 30th percentile or above) in reading real and pseudo-words. Three types of tests, phonological, successive, and simultaneous, together distinguished between those children who were diagnosed as reading-disabled and the normal readers in Grade 1. The risk of remaining a nonreader, in turn, was predicted by an extremely poor level of functioning on two successive and two phonological tasks.
We conclude, then, that the true dyslexic is characterized by a specific deficit in successive processing, in spite of an average or above average score on the three remaining processes, whereas the generally poor reader may have lower than average scores on some of the three other PASS measures as well. There are two other possible PASS profiles:
1. Some poor readers may not have a subaverage score in any of the PASS tests; the explanation for poor reading could be found variously in the absence of a literacy environment, poor instruction, and/or detrimental motivational and emotional conditions.
2. Even among dyslexics, there can be heterogeneous groups in terms of their performance in successive tests. This latter possibility was raised first by Torgesen and Houck (1980) and discussed further by Torgesen (1982). These investigators had identified a group of poor readers who performed at the average level in short-term memory (STM) measures (digit span, letter span, and word span). The issue has resurfaced in the discussion of double deficit. Double deficit is a deficit in phonological awareness as distinguished from a deficit in rapid automatic naming, of not only letters and words, but also colors and objects (Wolf and Bowers, 1999). The suggestion, open to argument, is that some dyslexics may have one or the other deficit, with those having both being the poorest readers.
Can Luria’s conceptualization of successive processing and CAS measures of successive processing help in understanding the issue? Luria viewed successive processing in terms of a sequence of movements as much as organizing ideas and events in succession (Luria, 1966a: 74,1973; Dasetal., 1979). Both execution of a series of movements smoothly, such as continuing a series of writing (for example, +++–+++—+++—) and fast articulation of a fixed series of words (for example, cat-wall-hot, cat-wall-hot), which Luria termed kinetic melody, make a minimal demand on memory. However, the first task has almost no load on STM, as the series is visually accessible at any time during the performance.
Speech rate, we suggest, is closer to a kinetic melody. Inasmuch as the rehearsal part of the phonological loop is close to the kinetic melody description, it represents successive processing. It also shares the same general region of the brain as associated with successive processing. Our research has made use of both kinds of successive tasks (Das, Naglieri, and Kirby, 1994). Among the subtests of CAS, we include speech rate (cat-wall-hot, cat-wall-hot), serial recall of words, sentence repetition (Naglieri and Das, 1997: 145), and naming speed for simple high frequency words (not included in the CAS). These tests have been used in predicting reading ability.
A fresh look at successive processing is warranted in the light of new findings on the brain-related correlates of the reading process. We have held on to the view that successive processing is not solely verbal and simultaneous processing is not solely nonverbal (Das et al., 1979), following Luria. The nonverbal part of successive processing is illustrated by the task called series completion (+++—…) and by similar tasks, such as copying hand movements and reconstructing a serial order of turning a row of five to seven chips presented in a predetermined random order, as previously used (Das, Naglieri and Kirby, 1994).
Perhaps, successive processing can be divided into two kinds of operations—verbal operations, which require phonological coding, and nonverbal operations, which require reconstructing the temporal order of movements. Both share the overarching process of serial ordering. Such a division may be related to deficiencies in two anatomical components—the magnocellular system and the cerebellar functions. Both of these deficiencies can cause difficulties in recoding and in the production of movements in a temporal order. As briefly reviewed by Frith (1999: 206):
If expressed at the cognitive level, both theories may imply a temporal processing deficit. Fast temporal processing may be a basic characteristic of all perceptual systems, visual as well as auditory, object-based as well as speech-based. Slower-than-normal perceptual processing might well compromise the development of a phonological system.
The results of our most recent investigation into this issue suggest that phonological awareness alone is an insufficient predictor of reading development. We will refer to a longitudinal study of children from kindergarten to Grade 3. In this study it was shown that verbal STM measures such as serial word recall as well as naming speed remained as viable predictors, even when letter recognition ability and phonological awareness were partialled out (Parrila and Kirby, 2000). These results could not be obtained if a phonological deficit alone was sufficient.
In our concluding comments we do not have to ask the rhetorical question—Is Luria relevant? Instead, we suggest looking beyond the narrow confines of phonological awareness in order to gain a better understanding of reading and its connection to language.