The mutual leavening of, and interplay between, science and practice in clinical neuropsychology is addressed in terms of several principles that are thought to have rather general applicability. An example of these interactions in the case of the development of the syndrome of nonverbal learning disabilities and the "white matter" model designed to account for its developmental manifestations and dynamics is provided. It is concluded that clinical practice and the science of neuropsychology should continue to reap considerable benefit from the principles nascent in the scientist - practitioner model.
Discussion of the interactions between science and practice on the occasion of this award arises because of two reasons: (1) my conviction that the scientist - practitioner model has been of crucial importance with respect to my own scientific and professional endeavours; and, (2) the very positive impact that it has had on the education and training of graduate students in clinical neuropsychology with whose preparation for science and professional practice I have had the privilege to be involved. The model has been useful, fruitful, and heuristic on both counts.
What follows are some reflections on the dimensions of science - practice interactions that I feel are particularly important at this juncture in the evolution of Canadian psychology in general, and clinical neuropsychology in particular. They reflect my experiences as a scientist - practitioner and they articulate many of my views regarding the important dimensions of the science and practice of neuropsychology for the foreseeable future (Rourke, 1991a).
A Note on Format
Each of the sections that follow begins with a statement of the principle involved; this is followed by an elaboration of it. Principles involving the scientific dimensions of practice are followed by those relating to the impact of practice on science. Hopefully, notions regarding some of the important science practice interactions nascent within these principles will emerge as a result of this exercise.
The Science of Practice
Principle 1: Replicability is one of the basic hallmarks of science. It is a sine question for scientific advances. It is obvious that considerations of reliability permeate scientific endeavours in psychology. Indeed, it is with some pride that psychologists boast of their commitment to the establishment of reliable procedures and to their objective measurement. An important step in the establishment of reliable results in psychological investigatory efforts is the adoption of a standard procedure that is well described and amenable to straightforward replication in other laboratories.
The analogue of these dimensions in professional practice is the necessity for reliable assessment instruments and standardized administration and scoring protocols for them. Indeed, one would expect that virtually all aspects of assessment, including communication between practitioners, would be enhanced as a function of the extent to which standardized procedures are adopted and utilized. Of course, the measurement of the extent to which reliability is achieved should be the norm rather than the exception if confident conclusions regarding clients are to be framed.
But, reliability, however well established, is not validity. This is especially troublesome for professional communications when inter - rater reliability is confused with validity. For example, consider the ordinary scenario that unfolds when a naive audience observes the machinations of a skilled illusionist. The illogical conclusions regarding cause and effect that members of the audience formulate as a result of the performances transpiring before their eyes are, in effect, a type of consensual validation; otherwise the illusionist would need to keep his day job. In any case, the point to be made here regarding replicability is simple: Reliable (i.e., superior inter - rater reliability), yes; valid, no.
Consensus among experts may be sufficient to start the painstaking task of establishing reliability in (say) diagnosis. But, there is no substitute for determining the validity of that diagnosis. Of course the same principle would apply with respect to the validity of intervention/therapy.
Principle 2 (re: Content/Coverage Validity): There is no substitute for the valid sampling of all relevant dimensions of behaviour. Everyone would agree that it is ludicrous to imagine that one could understand the scientific dimensions of eye - hand coordination by studying the "eye" but not the "hand." It does not appear to be equally obvious to some, however, that it is necessary to measure the relevant dimensions of sensation/perception, motor/psychomotor skills, language, problem - solving, and concept - formation (with attention and memory thrown in to boot) if one's aim is to understand brain - behaviour relationships in a human being. To do less than this would run the risk of missing a relevant dimension of the client's neuropsychological make - up: That is, the patient may "say" something that the neuropsychologist does not "hear."
The gold standard in neuropsychological assessment with respect to content validity is clear and straightforward: Unless all relevant dimensions are measured, none should be. The probability of false positives, false negatives, and other grossly erroneous conclusions increases as a function of the narrowness of the assessment procedure. An obvious example of this is the sheer lunacy involved in making statements about "memory" (on the basis of tests for various dimensions of "memory") without knowing (i.e., measuring) concept - formation, problem solving, word - finding, attentional capacities, and so on.
But what is meant by the phrase, "all relevant dimensions"? The following discussions of other types of validity constitute the answers to this query.
Principle 3 (re: Concurrent Validity): Science is not a process of answering questions (that's technology); science is a process of asking the right questions. The competent scientist - practitioner should direct, not follow, the inquiry vis - a - vis a client, just as the competent scientist chooses the relevant dimensions of experience for examination. An example from "pure science" should suffice to demonstrate the relevance of this principle.
Newton spent no time on the quite relevant questions regarding what would happen to his head if, instead of an apple, a squash or a rabbit or a boulder had fallen on it. Rather, he turned his mind to the possibility that objects may be attracted in any direction if there is a force that determines that attraction. Our knowledge about gravitational forces might have been delayed for some time if Newton had been concerned with the practicalities and technological innovations that arise from the systematic study of the fate of falling objects. To our benefit and Newton's credit, he was interested in studying the more general principles of movement and force. Hence, he asked the right question: Does an apple fall because of inertia, or is it attracted in a particular direction because of a force?
The analogue of this exercise in clinical practice is seen in the misplaced devotion to answer referral questions. After all, who would expect all, or even the majority of, referral questions to be relevant? For example, should one tailor one's neuropsychological assessment to answer a referral question such as: "Organicity?" or "Memory Disturbance?" If one does, one may very well be doing more harm than good. An illustration from my clinical practice may help to make this point.
Many years ago, when working in a multidisciplinary mental health setting, I received a referral that consisted of the client's name, age, and other identifying information, and the referral question of "Organicity?". Dutifully, we carried out our usual comprehensive neuropsychological examination of the client. In this particular case, it took the better part of a working day to complete the entire examination. When it came time to construct the report, I asked that the identifying information regarding the client be typed at the top of the page, and that a dozen or so lines be skipped, followed by the single word "No." Then, a few more skipped lines, followed by my signature. There were many reasons why I did this rather than answering "yes" - not the least of which was that I knew from experience in this setting that affirmative answers to the question of "organicity" meant almost certainly that active intervention to deal with the client's pressing problems would be deemed useless. In a word, saying "yes" to organicity (whatever is meant by this term) meant saying "no" to therapy.
As one might expect, the referral source was somewhat miffed by my "report" ... and proceeded to ask me several very pointed (and, at last, relevant) questions regarding the client's neuropsychological status. In addition to answering these questions in a subsequent report, I posed some of my own (that I thought had been left out by the referring party) and answered these as well.
I learned several things from this exercise, not the least of which is that the scientist - practitioner should never descend to the level of technologist. One should always keep before one's mind the relevance of questions and the opportunity to pose better ones. Of course, the principal reason for adopting this tack is the welfare of the client (our first and foremost obligation). Had I answered the "organicity" question with a "yes" (the client was, in fact, suffering from some impairment in neuropsychological skills and abilities), the client would, almost certainly, have been considered to be an unsuitable candidate for psychotherapy. As it turned out, following my commiserations with the referring agent, the client (who had suffered a significant traumatic brain injury with apparent negative consequences with respect to his neuropsychological status) was viewed as a good candidate for psychotherapy and other modes of active intervention. This eventuated in an entirely appropriate and efficacious therapeutic path for the client. The probability approached zero that this path would have been followed if the appropriate questions had not been asked.
To iterate, persons do have neuropsychological dimensions that are usually quite relevant with respect to their continuing attempts at adaptation (more on this below). Valid assertions (i.e., concurrently valid statements) regarding their present status are possible, even probable. But, confining one's scope as a clinical neuropsychologist to the musings of other professionals almost always has a negative impact on concurrent validity ... with a correlative negative impact on the welfare of the client. Even worse, following the dictates of other professionals with respect to the actual tests and measures that one should employ (e.g., "the schizophrenia scale from the MMPI") is tantamount to malpractice. Another professional may initiate referrals for neuropsychological assessment, but it is the purview of the responsible clinical neuropsychologist to ask and answer the relevant questions.
Principle 4 (re: Predictive Validity): There is no substitute for knowledge regarding the natural history of neurological disease, disorder, and dysfunction. Predictions made outside of the context of the natural history of neurological disease and available treatment modalities (i.e., outside of the context of significant moderating variables) are bound to be quite limited, and may be counterproductive.
For example, no competent practitioner would apply behavioural shaping techniques to shorten coma in a person suffering same following a blow to the head.
The failure to appreciate the context of behaviour is not a characteristic of the vast majority of therapists. That said, it is important to note that some practitioners appear prepared to treat deficits regardless of their origin and probable course. Apart from the very obvious absurdity of this particular point of view, the practitioner who is ignorant of the natural history of traumatically induced coma may also be unaware that therapeutic interventions aimed at prolonging - rather than shortening - coma are routinely applied in an effort to decrease post - traumatic complications of traumatic brain injury and other neurological disease processes.
More generally, imagine the sorts of therapeutic plans that might be generated for persons with muscular dystrophy (a progressive, degenerative disease) or multiple sclerosis (a disease that is often marked by periods of symptom fulminations followed by periods when the patient is almost symptom - free) if the practitioner is not conversant regarding the natural history - that is, the developmental course - of the disease in question! I cite these examples simply to establish the point that the natural history of a neurological disease is a very important dimension that has very real and imperative implications for treatment.
In the practice of clinical neuropsychology, one should be informed not only with respect to this particular dimension of predictive validity (i.e., the natural history of the disease in question). Indeed, one needs also to be knowledgeable with respect to the relative predictive accuracy of different neuropsychological measures vis - a - vis the panoply of types of neurological diseases and disorders with which clients in one's practice typically present. For example, we know that the earlier and the more severe the mnestic impairment in some dementing diseases of adulthood, the more quickly the disease is likely to progress. On the other hand, psychomotor deficits, in such instances, have little bearing on this prediction. In many ways, the exact opposite is the case for children suffering from some forms of pediatric neurological disorder.
In all of this, it must be borne in mind that knowledge of this sort does not eventuate in absolutely perfect predictions of all possible outcomes. However, it does set the parameters within which individual variability is likely to operate. In this sense, it informs treatment by helping to set realistic goals and to pinpoint probable areas for significant positive change with intervention.
Once again, we see that science informs practice and is an indispensable adjunct to the clinician. Indeed, failing to keep informed about advances in knowledge regarding natural history and psychometric predictive validity vis - a - vis various forms of neurological disease, disorder, and dysfunction is a seriousproblem - serious enough, in my view, to constitute a significant breach of professional responsibilities to one's clients.
Principle 5 (re: Construct Validity): Tests do not necessarily measure what their names (or reputations) denote. Dimensionality needs to be demonstrated. Very often, clinicians slip into the very counterproductive habit of assuming that (say) intelligence tests measure intelligence; or memory tests, memory; or attention tests, attention. For example, the Peabody Picture Vocabulary Test was designed as a measure of receptive vocabulary. One feature of this test, however, is that the response alternatives on it require the scanning of a full page of four line drawings. Thus, for a person with a left homonymous hemianopsia/hemiagnosia, deficiencies on this test may very well reflect problems in perception of, or attention to, the left visual field, rather than shortcomings in receptive vocabulary.
As alluded to above in connexion with content validity, it may be the case that tests that are called measures of memory and that are designed specifically for the determination of assets and deficits in various dimensions thereof may cloud more than they reveal. For example, deficits exhibited by a particular client may actually reflect problems in attention, word - finding, concept formation, or any number of other important neuropsychological dimensions; hence, the conclusions regarding "memory" may be completely off the point. In this case, clarity of exposition with respect to the manner in which the test is styled may lead to the misappropriation of the client's neuropsychological assets and/or deficits. The fault in this process is the failure of the clinical neuropsychologist to step back and take note of the difference between the advertised nature of the test and its construct validity. A rose by any other name may still be a rose; a test that includes "rose" it its title, however, may have nothing at all to do with roses!
Our knowledge about the construct validity of measures commonly used in neuropsychological assessment is growing, especially as the result of the judicious use of confirmatory factor analysis and other sophisticated psychometric techniques (e.g., Francis, Fletcher, Rourke, & York, 1992). For now, however, it would be best to refer to tests of undemonstrated dimensionality by some neutral term rather than by a moniker that denotes facets of memory, attention, language, or the like. In the last analysis, aspirations to construct validity (as spread in the names chosen for particular tests) may be nothing more than idle fantasy. Unvalidated fantasies of this sort have a way of hindering advancement, not only with respect to science but also with respect to the clinical characterization of clients.
In our own laboratory, our version of a test originally developed by Donald Doehring as a measure of speed of visual processing is referred to as the Underlining Test (Rourke, Fisk, & Strang, 1986). This is our practice because all of its 14 subtests involve a common response modality: the underlining of target items interspersed with similar distractors. We are happy with the name of the test. Indeed, the name of the test need not change once its dimensionalities for various developmental levels and neurological disease entities are specified. Rather, the test can be used with this knowledge in mind. Practitioners who wish to measure the dimensions tapped by the test under particular conditions need not be handicapped by employing a measure of largely unknown, though clearly labeled, attributes. At some point, these dimensions will be specified in terms that are consensually validatable. This will occur when the test is used by a sufficient number of scientist - practitioners whose intent and expertise are applied to the thorny problems involved in the determination of the dimensions of its construct validity.
Principle 6 (re: Ecological Validity): Generalizability is an aspiration of all good science. Generalizability is a necessity for useful assessment. The very old story about looking for a lost ring under a lamppost rather than in the dark where it went missing is usefully referenced within this context. Very often, clinicians measure what they can measure, without regard to the prevailing dimensions and adaptive demands of their clients' environments. The use of reliable measures that are valid in terms of the aforementioned standards is all well and good; something worthwhile may be achieved thereby. But, if the client's current preponent adaptive difficulties are not materially understood and, hopefully, lessened by reference to the results of the assessment modalities employed, the assessment procedure itself is necessarily limited. In a word, this dimension of validity has to do with the extent to which the assessment leads to an efficacious treatment plan.
An adequate neuropsychological assessment should yield a compendium of adaptive assets and deficits, the dynamics of these, and the conditions under which they emerge (e.g., in novel versus well - learned circumstances). This is the type of assessment regimen that is most likely to lead to treatment plans that benefit those assessed. To date, however, this dimension of assessment has been given very short shrift in both research and practice in clinical neuropsychology.
One consequence of this dearth of attention is that there has emerged in our field a continuing and very marked tendency to eschew the efforts required for the development and evaluation of assessment regimentreatment plan interactions. In place of such efforts, there has been an unfortunate disposition marked by a tendency to favour the dogged application of notionally derived and largely untested treatment regimens that, in many instances, have no more than face validity. The springing up of rehabilitation centres offering "cognitive retraining" and a multiplicity of other untested modes of interventions are the best examples of this very deplorable trend. Although some of these centres actually make an effort to evaluate outcomes and the relationship of assessment modalities to outcomes, the sad truth is that science is largely forgotten in this rush to relevance ... and wealth (Putnam & Adams, 1992; Rourke, 1991a). The blanket application of these and other modes of intervention prior to the systematic evaluation of their efficacy, much less specificity, is unconscionable. In such instances, the scientist - practitioner model is not only a beacon that highlights these misadventures, it is also an important ideal that serves as a guideline for their more desirable alternative.
Principle 7: Each client should be approached as one would an experiment. Scientific method, including experimental and psychometric approaches, provides a beneficial, heuristic, and communicable framework for assessment and intervention. The scientific method is particularly adaptible to clinical assessment. One observes the phenomena in question, formulates hypotheses regarding their nature and dynamics, and tests and refines these educated guesses by empirical means. The empirical means adopted for such investigations are those measures of behaviour that have demonstrated reliability and validity. The findings of the assessment (experiment) and their implications for the present (concurrent validity) and the future (predictive validity), as well as treatment/intervention (behaviour change/ecological validity) are then couched in terms of dimensions that are clear and unambiguous (construct validity). If called for, additional examinations (future directions for research) are also suggested and framed in empirically and theoretically justifiable formats.
We turn now to a discussion of the manner in which practice leavens science.
The Practice of Science
Principle 8 (re: Mechanism and Dynamics): Too often, neuropsychological science is concerned with mechanism at the expense of dynamics. And mechanism is often viewed within the rather narrow constraints imposed by static views of replicability. An example may serve to illustrate this principle. In most of the early work - and, unfortunately, some current studies - dealing with dichotic listening, the "warmup" period was thought to be irrelevant. Indeed, data collected before the subject reached a level of "stable responding" was most often ignored. Most investigators considered the warm - up (i.e., in their view, unstable) period of responding as nothing more than bothersome and irrelevant noise in the system. Hence, the less attention paid to it, the better. However, the consistent and widespread observations of their brain - impaired clients by clinical neuropsychologists served to highlight the shortcomings of this position. An example of this consistent and widely held view should suffice to make this point:
Much of the grief experienced by persons with many types of brain disease occurs when they encounter novel situations to which they are expected to adapt in a "normal" (i.e., efficient, timely, and adaptive) manner. But, such persons often experience confusion, alarm, word - finding difficulties, and any number of other deficits when faced with such novel circumstances. This leads very often to debilitating levels of anxiety that prevent them from adapting in an appropriate manner to the situations at hand. Only after repeated desensitization procedures and the provision of an overlearned code to deal with such situations will their responding rise to an adaptive level. And the level to which it arrives may very well be normal and adaptive. Were we only to measure the latter, we wouldnot appreciate the anxiety - provoking precursors taking place during this type of warm - up period (i.e., the prelude to the exhibiting of adaptive behaviour) that need to be overcome in order to weather such a storm. In a word, we would not have appreciated the process of learning that has eventuated in the product that we see at the end. Failure to appreciate the "warm - up" necessary to understand this complex interaction precludes our understanding of it.
One lesson to be learned here is that noise very often becomes reality in the life of the person with brain disease. To ignore this simple finding and its theoretical implications is to relegate oneself to the garbage heap of irrelevance. In effect, not telling the whole story becomes a function of not looking for it.
Even in the case of persons with completely normal brain functions, it is important to pay attention to their responses to novel circumstances. For example, one prevailing theory of brain - behaviour relationships in adults (Goldberg & Costa, 1981) and children (Rourke, 1982, 1989) suggests that novel situations for which the person has no pre - existing code will invoke (a) the activity of primarily right hemispheral systems during the formulation of this code, and (b) primarily left hemispheral systems once the response modality becomes codified and, hence, amenable to stereotypic unfolding. Is it any wonder, then, that human adults whose linguistic capacities are mediated principally by systems within the left cerebral hemisphere do not arrive at stable responding (i.e., a right ear advantage) to paired digits in the dichotic paradigm before they pass through a stage of "unstable responding" (i.e., a left - ear advantage or no ear advantage at all)?
Response to novelty, the gradual waning of that response as a result habituation/inurement and/or the development of a routinized code for dealing with it, and the application of this code in a stereotyped manner are dimensions of scientific interest per se. Choosing to study serialized, though distinct and separated, mechanisms of response to novelty, and then habituation, and then code formation, and then stereotypic application, in different investigations, with different subjects, and with different paradigms does little or nothing to shed light upon the dynamics of these dimensions in the individual subject over time. Hence, none of this does anything to promote understanding of life as lived - which, after all, is the criterion against which our science is, or should be, measured.
More generally, it has become clear in all aspects of developmental neuroscience that there is no substitute for the investigation of dynamic change in brain and behaviour over time in the short - run laboratory situation and within and between relevant developmental epochs. One reason for this emphasis is that there is an increasing awareness that similarities and differences in developmental dynamics within a task are as important to understand as are these dimensions in persons progressing through different developmental levels.
Another reason to inculcate this particular principle within one's approach to developmental neuropsychological science is that the child may respond at the same level as does an adult, but through the use of quite different mechanisms. Stated simply: The child and the adult may perform at identical levels of performance, but the mechanisms and dynamics through which they so do may differ. In this, as in more examples that one may care to mention, adultomorphic mechanisms cannot be expected to encompass the entire array of childhood dynamics. Only through the invocation of models that emphasize interactions between and within mechanisms at different phases of learning and development do these types of dynamics yield to understanding (Rourke, 1982).
Let us consider the applications of this principle within a very different context, viz., neurophysiological responsivity. The veritable explosion of neuropsychological knowledge that has resulted from the use of dynamic paradigms involving evoked potentials (e.g., Dool, Stelmack, & Rourke, 1993) is one example of the application of this principle in research. More generally, it is expected that results of studies employing cerebral blood flow and other sophisticated neuroimaging techniques within the context of the dynamic interplay of subject and stimulus modality, complexity, and other dimensions will yield much of value to neuropsychology (Rourke, 1991a; Rourke & Brown, 1986).
Eschewing static, mechanistic models of brain - behaviour relationships was stimulated as much by the limited ecological validity of the traditional neuroimaging techniques as by the limited ecological validity of static experimental paradigms in traditional psychology. In both cases, dimensions previously considered as nothing more thannoise are now seen as crucial signals of the manner in which brains operate and how they come to function under differing information processing circumstances (Rourke, 1982; 1989).
Clinical neuropsychologists - because of their concern for understanding and dealing with the unstable responding of their clients and for the dynamics of disordered learning, and so on - have long considered these dimensions of considerable import. It is time that the imperatives of ecological validity implicit within this argument, however inadequately and vaguely conveyed, be saluted. Variability and instability are crucial dimensions of behaviour in persons with brain impairment and, as such, should be the subject of intensive scientific inquiry.
Principle 9 (Answers versus Questions): Answers are not nearly as important as are important questions. The attentive consumer of this presentation will immediately recognize this principle as a variation on one used above in connexion with the contributions of science to practice. The gist of this issue is straightforward: Too often, scientists propose elegant answers to trivial questions. The questions are answered, but the field does not, thereby, move forward. Part of the solution to this problem rests in the definition of what constitutes a good question.
The resolution of this is not as complex as might, at first, seem to be the case. For example, clinicians want answers to questions regarding reliability of diagnostic classifications. They want to know which features of a reliable assessment are most valid with respect to the concurrent and predictive validity of the classificatory schemes proposed. They want to know whether and to what extent the dimensions that are thought to be relevant are, in fact, relevant for the contexts within which they have no choice but to operate. They want to know whether any dimensions of this entire exercise map onto issues of relevance to the developmental demands of their patients.
The point to be emphasized in this context is that the neuropsychological scientist - practitioner is in the best position to provide answers to these queries. For the (pure) scientist to wait for the clinician to proffer the right questions, or for the (pure) clinician to offer same, is a division of labour that simply will not wash. The problems are too delicate; the stakes, too high.
That said, there is very good reason for aspiring scientists to listen intensively to the urgings of experienced clinicians. The determination of reliable and valid brain - behaviour relationships, as Hebb (1949) so eloquently stated, always begins with the disciplined observations and insights of astute observers of behaviour (i.e., clinicians). To ignore this input is to separate neuroscience from the real world. Although it is exceedingly improbable that neuropsychological researchers would endorse such oversight, the fact remains that much neuropsychological research continues without reference to this rich source of insight and trove of clinical imperatives. Science that gets too far from this becomes esoteric and irrelevant.
There is no substitute for the disinterested study of one's patients. This study should be scientific at its most objective heights. Practice without a scientific approach leads to monotonous repetition and burn - out. Science without clinical input and acumen leads to the kind of monotonous repetition of boring studies such as those that all but killed the field of aphasiology. Following such a course unabated will lead to the same dead - ends that are currently manifest in much of neuropsychological research in the areas of "memory" and "frontal lobe syndromes". Unless the clinicians in our field send out a wake - up call to the "scientists" who are - in their own terribly encapsulated manner - viewing and "experimenting" with respect to these issues, the same sort of static, old - fashioned models and theories will continue to be developed. As we all know, this sort of exercise and the products developed thereby are quite nicely geared to the acquiring of a full professorship. Unfortunately, these are not the perspicacious efforts that have any probability of promoting significant advances in science or practice.
Principle 10 (Role of insight, model building, and theory in science): There is no substitute for theory development, model construction, and systematic hypothesis - testing. Note that there is no difference between science and practice in these regards. In his monumental work regarding the place, purpose, and role of the university in the intellectual life of society, John Henry Cardinal Newman (1852;1959) made a clear distinction between happenings and experiences. He noted that the vast majority of persons whom he had encountered after theirpursuits of maritime adventures throughout the world - who had seen, heard, and otherwise sensed the multitude of its multivaried presentations - appeared to be dull. Looking into their eyes whilst they spoke of such events led Newman to opine that, however accurately they had portrayed them, they had not - in any real sense experienced (i.e., understood) them. They had "seen," and "heard," and "felt" a great deal. But they did not appear to have assimilated these experiences in any meaningful manner. Thus, he suggested that it is possible - indeed, probable - that there is no necessary connexion between simple exposure to stimulus arrays and learning. More generally, he suggested that education has to do far less with stimuli (i.e., happenings, events) than with their assimilation within categories of understanding (i.e., experiences).
Although this may not, at first blush, strike one as a particularly astute clinical observation, it does illustrate the point that I wish to make: There is no such thing as a fact. By extension, there is no meaning to data per se. It is illusory to maintain that "facts speak for themselves". Facts are inert until they are illuminated by a model or theory. They are combinations of dross and ore until their composition is subjected to the scrutiny of science (read: scientific models).
Piaget's assimilation/accommodation theory serves as an important model for the scientist - practitioner because it addresses directly the most important elements of these complex issues. Piaget (1954) suggested that progressively more advanced equilibrium of levels of assimilation/accommodation characterize advances in intelligence, progress in science, and understanding of psychological dynamics. His explanation of this process is, from a theoretical standpoint, internally consistent and meaningful. Apart from the attempts to test the deductions of his model (and there are many), I would only add that our primitive understanding of brain - behaviour relationships would be expected to advance as a function of our capacity to generate testable models that embrace the complexity of clinical presentations, and that allow for the elucidation of the developmental dynamics nascent therein.
Competent neuropsychological clinicians know that there are no "facts" in the Joe Friday sense of the term. There are only data that are usually amenable to a fairly large number of inclusive and exclusive interpretations. It is time that neuroscientists took note of this, and responded appropriately. Better still, we should encourage the development of sound scientist - practitioners who have the capacity to confront and deal with this as a challenge worth taking on, as a role that is crucial for the development of the field, and as a vocation that has endless possibilities for progress.
We turn now to a brief description of the manner in which my colleagues and I have (a) developed and described the content and dynamics of the syndrome of nonverbal learning disabilities (NLD), and (b) fashioned a model for the elucidation of its complex contents and dynamics. It is hoped that a brief description of this process will serve as an example of the manner in which science can contribute to practice - and practice to science. Although it is hoped that this presentation is largely self - explanatory with respect to the issues raised to this point, some parenthetical references to the foregoing principles are cited.
Nonverbal Learning Disabilities
HISTORICAL BACKGROUND OF THE SYNDROME AND THE WHITE MATTER MODEL
Since 1971, we have engaged in the intensive investigation of two subtypes of children with learning disabilities (LD). As a result of our clinical observations and empirical investigations, we are able to state with considerable confidence the characteristics (content validity) of the two subtypes, as follows.
Children of one subtype (referred to as Group R - S) exhibit many relatively poor psycholinguistic skills in conjunction with very well - developed assets in visual - spatial - organizational, tactile - perceptual, psychomotor, and nonverbal problem - solving skills. They perform very poorly in single - word reading and spelling and significantly better, though still impaired, in mechanical arithmetic. Their outstanding problem is in the area of phonological awareness and processing. The model that we have developed to encompass these observations and research findings will not be presented here (see Rourke, 1989).
The other subtype - which we refer to as the NLD syndrome - exhibits outstanding neuropsychological deficits in visual - spatial - organizational, tactile - perceptual, psychomotor, and nonverbal problem - solving and concept - formation skills, within a context of clear neuropsychological assets in psycholinguistic skills such as rote verbal learning, regular phoneme - grapheme matching, amount of verbal output, and verbal classification. Children with NLD, a term coined by Myklebust (1975), experience their major academic learning difficulties in mechanical arithmetic, while exhibiting advanced levels of word - recognition and spelling. Both of these subtypes of children with LD have been the subject of much clinical and scientific inquiry in our laboratory (for basic research and reviews and some clinical examples, see Rourke, 1975, 1978, 1982, 1987, 1988a, 1988b, 1989, 1993; Rourke, Bakker, Fisk, & Strang, 1983; Rourke & Del Dotto, 1994; Rourke & Finlayson, 1978; Rourke & Fisk, 1988, 1992; Rourke, Fisk, & Strang, 1986; Rourke & Fuerst, 1991, 1992; Rourke & Strang, 1978, 1983; Strang & Rourke, 1983, 1985a, 1985b), and have been subjected to clinical, empirical, and theoretical scrutiny by others (e.g., Bieliauskas, 1991; Fletcher, 1985; Sparrow, 1991; Torgeson, 1993; van der Vlugt, 1991; van der Vlugt & Satz, 1985).
CHARACTERISTICS AND DYNAMICS OF THE NLD SYNDROME
The principal clinical manifestations (content) of the NLD syndrome, which we identified through a process of intensive clinical examination, are as follows:
(1) Bilateral tactile - perceptual deficits, usually more marked on the left side of the body.
(2) Bilateral psychomotor coordination deficiencies, often more marked on the left side of the body.
(3) Outstanding deficiencies in visual spatial - organizational abilities.
(4) Marked deficits in nonverbal problem - solving, concept - formation, hypothesis - testing, and the capacity to benefit from positive and negative informational feedback in novel or otherwise complex situations. Included are significant difficulties in dealing with cause effect relationships and marked deficiencies in the appreciation of incongruities (e.g., age - appropriate sensitivity to humour).
(5) Very well - developed rote verbal capacities, including extremely well - developed rote verbal memory skills.
(6) Extreme difficulty in adapting to novel and otherwise complex situations. An over - reliance on prosaic, rote (and, in consequence, inappropriate) behaviours in such situations.
(7) Outstanding relative deficiencies in mechanical arithmetic as compared to proficiencies in reading (word - recognition) and spelling.
(8) Much verbosity of a repetitive, straightforward, rote nature. Content disorders of language, characterized by very poor psycholinguistic pragmatics (e.g., "cocktail party" speech). Misspellings almost exclusively of the phonetically accurate variety. Little or no speech prosody. Reliance upon language as a principal means for social relating, information gathering, and relief from anxiety.
(9) Significant deficits in social perception, social judgment, and social interaction skills. A marked tendency toward social withdrawal and even social isolation as age increases.
(Such children are very much at risk for the development of socioemotional disturbance, especially "internalized" forms of psychopathology.)
We have found that the NLD syndrome is manifest most clearly on a "developmental" basis and that it persists into adulthood (Rourke & Fisk, 1992). However, it is also seen in the clinical presentation of persons suffering from a wide variety of types of neurological and neuroendocrine disease, disorder, and dysfunction. These include significant tissue destruction within the right cerebral hemisphere (Rourke, Bakker, Fisk, & Strang,1983) and some types of hydrocephalus (Fletcher, Brookshire, Bohan, Brandt, & Davidson, 1995), callosal agenesis (Smith & Rourke, 1995), congenital hypothyroidism (Rovet, 1995a), and other pathological processes that have as one of their results significant destruction of neuronal white matter (long myelinated fibers). Other examples include persons with Williams syndrome (Anderson & Rourke, 1995; MacDonald & Roy,1988; Udwin & Yule,1991) and Asperger syndrome (Klin, Sparrow, Volkmar, Cicchetti, & Rourke, 1995), who exhibit virtually all of the assets and deficits of the NLD syndrome. (For an up - to - date account of the diseases and disorders of childhood wherein the NLD syndrome is manifest, the reader should consult Rourke [1995a] ). These are examples of the manner in which we have been able to demonstrate the generalizability of the NLD syndrome.
In addition to describing the clinical features of this syndrome, a model to explain the syndrome's dynamics has been proposed (Rourke, 1987; 1988b; 1989). The model involves an extension of the theoretical tenets of Goldberg and Costa (1981), some integration with Piagetian developmental theory, and some relationships to known age - related developmental changes in neuropsychological test performance. For a full description of the syndrome and the "white matter" model designed to account for it, the interested reader is referred to Rourke (1989, 1995a) and Tsatsanis and Rourke (1995).
It is proposed in the model that the principal or primary dimensions of the NLD syndrome are deficits in visual - perceptual - organizational abilities, complex psychomotor skills, tactile perception, and nonverbal problem - solving, and assets in most rote verbal and some simple motor and psychomotor skills and abilities (Rourke, 1989). These formulations were arrived at on the basis of clinical observations by ourselves and other practitioners. Confirmation of these dimensions as primary (construct validity) arises from the results of recent studies (e.g., Casey, Rourke, & Picard, 1991; Harnadek & Rourke, 1994). It should be emphasized that, in the Rourke (1989) model, the patterns of academic and psychosocial deficits experienced by individuals who exhibit this subtype of LD are viewed as the direct result of the interaction of the primary, secondary, tertiary, and linguistic neuropsychological assets and deficits that are outlined in Figure 1.
For example, considering the hypothesized "deficit" stream, the primary neuropsychological deficits experienced by the child with NLD are seen as having to do with aspects of tactile and visual perception, complex psychomotor skills, and the capacity to deal adaptively with novel material. Such deficits would be expected to eventuate in disordered tactile and visual attention, and stunted exploratory behavior; in turn, problems in memory for material delivered through the tactile and visual modalities as well as deficits in concept - formation and problem - solving would be expected to ensue. This set of deficits would be expected to eventuate in the particular set of linguistic deficiencies outlined in Figure 1 (Rourke & Tsatsanis, 1995). The academic and psychosocial/adaptive deficiencies listed are the expected sequelae of these neuropsychological deficits. It is especially important to note that this set of neuropsychological deficits is expected to lead, in a necessary way, to a particular configuration of problems in psychosocial/adaptive behavior both within and without the academic situation (Rourke, 1988a, 1989; Rourke & Fuerst, 1992). As suggested above, reference to Figure 1 should be of some assistance in the understanding of our views regarding the content and dynamics of the NLD syndrome.
In a series of studies (summarized in Rourke & Fuerst, 1991), we have been able to demonstrate the concurrent and predictive validity of these formulations. Also, it has been possible to demonstrate that particular patterns of academic assets and deficits are reliably related to particular patterns of psychosocial dysfunction across the age - span of interest (Fuerst & Rourke, 1995). Thus, the investigative progression passed from systematic clinical observations to the formulation of the NLD syndrome and dynamics and, eventually, to empirical tests of hypotheses deduced from the model generated thereby. Virtually all results of studies in our own and others' laboratories have been consistent with deductions derived from the neurodevelopmental model designed to encompass and explicate the NLD syndrome and its dynamics.
Some other researchers who have pursued research along lines similar to our own (e.g., Grace & Malloy, 1992; Tranel, Hall, Olson, & Tranel, 1987; Voeller, 1986; Weintraub & Mesulam, 1983) have arrived at conclusions regarding particular salient dimensions of children with LD whose deficits resemble the NLD syndrome. Some have accentuated the "right hemisphere" nature of the deficits; others, the psychosocial dimensions; and still others, dimensions such as deficits in prosody. These formulations do not deal with issues regarding the relative importance of these dimensions. As noted above (and see Figure 1), our formulation of the NLD syndrome and model (Rourke 1987, 1988b, 1989) is explicit with respect to the dimensions of NLD that are thought to be causative and sequential (i.e., primary-> secondary -> tertiary-> linguistic) and dependent (i.e., academic and psychosocial). We have also been able to demonstrate that several of the developmental tenets of the model are supportable (Casey et al.,1991; Fuerst & Rourke, 1995; Harnadek & Rourke, 1994).
It is expected that further clinical observation and research will lead to extensions and elaborations of the NLD syndrome and the "white matter" model designed to account for its manifestations and dynamics (Rourke, 1989). At present, it would appear that the principal opportunities for so doing involve intensive neurodevelopmental investigations of children who suffer from a variety of pediatric neurological maladies in which white matter disease, disorder, and dysfunction are thought to play a significant role. Recent research along these lines (e.g., Anderson & Rourke, 1995; Don & Rourke, 1995; Fletcher et al., 1995; Klin et al., 1995; Picard & Rourke, 1995; Rovet, 1995a, 1995b) would seem to constitute a testament to such promise.
Finally, a treatment programme for children with NLD that has been applied with some success is outlined in Rourke (1989) and Rourke (1995b). We have taken considerable pains to relate the elements of this programme to the content and dynamics of the NLD syndrome. In addition, we have suggested explict strategies and interventions whose efficacy can be tested by empirical means. It is anticipated that the continuation of investigations and applications of the programme in various centres (e.g., Cermak & Murray, 1992; Cracco & Thierry, 1993; Foss, 1991; Williams, Richman, & Yarbrough, 1992), including our own (e.g., Ozols & Rourke, 1991;Rourke & Tsatsanis, 1994), will yield important information with respect to its efficacy and, in turn, lead to refinements of it.
With respect to the principles regarding the interaction of science and practice, the example from our own laboratory should be instructive: We have carried out intensive clinical examinations of thousands of clients and have found that there is a constellation of neuropsychological assets and deficits in a specific subset of them that is cohesive enough to constitute a syndrome. We have formulated a neuropsychological model to account for its developmental content and dynamics. We have fashioned a neuropsychological model to account for its basis in brain disease, disorder, and dysfunction. We have tested some dimensions of the syndrome and the model and have found them to be basically sound. Others who have tested them have come to the same conclusions. The elaboration of the "white matter" model to extend its ramifications for various forms of neurological disease, disorder, and dysfunction is well underway and shows no signs of abating.
We feel that the formulation of the NLD syndrome and dynamics and the development of the "white matter" model that speaks to its neurological mechanisms and dynamics exemplify the heuristic and productive interplay of science and practice. And we are extending this manner of proceeding to the development of models that will apply to other subtypes of LD that have emerged on a clinical basis and that have been replicated reliably in empirical classification research (see Rourke, 1985 and 1991b for examples of these).
Finally, we turn to an entirely different state of affairs with respect to science and practice - one that exemplifies much that can go wrong when flimsy and self - serving dogma are combined with shoddy reasoning.
A Final Note
Principle 11 (re: Deconstructionism and other ideological fads): There is no room in the science and practice of clinical psychology for "ist" approaches. By their very nature, "isms" (ideologies, as commonly styled) involve biased perceptions: That is, they either deny the validity of some dimensions of the phenomena under consideration or distort the relative importance of these dimensions. Rather than approaching the person or persons involved in the clinical event of relevance in an objective and disinterested manner, the "ist" has an agenda that, for all intents and purposes, employs the clinical event as grist for an ideological mill. Thus, particular clinical phenomena become exemplars of principles of the ideology in question, rather than dimensions that require understanding and care per se and for the sake of the individual(s) involved. The end result of this type of biased inquiry cannot help but constitute a gross misrepresentation of the facts of the case. To think that such systematic distortion could conceivably form the basis for intervention and care is silly. Instead, what arises in terms of "therapy" from such approaches is nothing more than the modus operandi formulated in terms of the ideology well before the client even appeared at the "ist's" doorstep.
Clinical psychology is in no need of purveyors of ideologies who assert and propound their dogmas instead of paying attention to the psychological dimensions of their clients. A moment's reflection on Sartre's "en soi - pour soi" distinction should serve to highlight the differences between the ideological standard - bearer and the prudent scientist - practitioner. Clients are protected when they are considered for the sake of themselves: that is, in and of themselves. They are abused to the extent that they are employed to propel and adumbrate a doctrine steeped in a dogmatic world - view. When reliable and valid dimensions of human behaviour are sacrificed on the altar of ideology, the result is, almost without exception, disastrous.
How would the scientist - practitioner choose to counter these deplorable trends? The solution is not easy. But it is clear and reasonably straightforward.
Although clinging to the scientific method is itself an act of faith, it is clear that this faith serves our clients and our discipline well. By its very nature, the scientific method aims to produce reliable data that have some measurable degree of validity. There is as much concern with what is not known as there is about what is known. It is simply unscientific to assert the truth of a proposition that has not been demonstrated. Indeed, no proposition is ever proven in any absolute sense. One sees only "through a glass darkly," and it is such incomplete perceptions that encourage further scientific work. The clear, uncomplicated, and unequivocal assertions of the true believer are the very antithesis of the humble and circumspect observations and impressions of the scientist - practitioner. In the last analysis, clients are well served by humility and circumspection, not by pomposity and dogmatic certainty.
The science of practice and the practice of science have served us well. Let us hope that our science and our profession will resist any temptations to shy away from these noble pursuits. We should be prepared to live with ambiguity and uncertainty. We should have the courage to eschew comfortable ideologies offering certainty and freedom from doubt. We should be open to and embrace the tantalizing wonder of insight that painstaking and disinterested inquiry yields. The scientistpractitioner should learn these lessons early and practice them even when it hurts. Our scientist - practitioner mission deserves nothing less.
Much of what I have learned about the scientist - practitioner model derives from the seminal contributions of Anne Anastasi and Ralph M. Reitan. Anastasi's notions regarding the essential and fruitful interactions between experimental and psychometric approaches to understanding human behaviour permeated my experiences of graduate school at Fordham. The insightful, consistent, and clear explications of such issues in her classroom presentations matched those in her voluminous writings. Reitan's notions regarding the heuristic nature of approaches to assessment that accentuate the distinctness of the individual as an experiment of nature and the necessity for objective and disinterested clinical inquiry have become part and parcel of my world - view. The manner in which he has grappled with the idiographicnomothetic controversy and his unremitting commitment to, and elucidation of, the multifaceted interactions of the practice and experimental/psychometric dimensions of clinical neuropsychology have served as a source of considerable inspiration for me and as the benchmark for contributions in our field. Scientist - practitioners everywhere owe both of these pioneers an enormous debt of gratitude.
Byron P. Rourke was the recipient of the Canadian Psychological Association's 1994 award for Distinguished Contributions to Psychology as a Profession. This is a modified text of the invited paper presented on the occasion of the bestowing of the award at the meeting of the Canadian Psychological Association, Penticton, BC, July, 1994.
Address for reprint requests: Byron P. Rourke, Department of Psychology, University of Windsor, Windsor, Ontario N9B 3P4.
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