Comments on 'Validity of Sensory Systems as Distinct Constructs'
Chia-Ting Su and Diane Parham (2014) wrote an interesting article that appears in this month's American Journal of Occupational Therapy. Their study involved use of confirmatory factor analysis to test constructs within sensory integration theory. Results of their analysis have rather broad implications and raise many important questions.
A highly popularized notion based on Dunn's (2001) Slagle lecture is that sensory processing can be identified as occurring within different systems where there might be over or under responsiveness to incoming stimuli. Su and Parham applied data to this model and could not confirm that this conceptualization fit their data. This in itself is a significant finding because it puts into question whether or not SOR/SUR models are the most appropriate way to explain problems with sensory processing.
Also germane to this finding is the concern that tools like the Sensory Profile confound analysis by including questions about temperament that may not have much or anything to do with a distinct 'sensory processing' factor. Su and Parham (2014) state, "the inclusion of items on the Sensory Profile that are highly sensitive to temperament is another plausible reason why the Sensory Profile factors differed from ESP factors in the current study." This is an issue that I have blogged about previously, particularly in context of the Shea and Wu (2013) article about children in the criminal justice system. I stated
This analysis should help us to more deeply understand that our current assessment tools, which are apparently measuring something, may not just be measuring a sensory processing construct. In my opinion, the assessment tool also includes many questions that are broad and general and could represent a number of behavioral phenomenon, primarily dependent on the interpretation or labeling of the examiner.
I believe that we should consider pausing when we use tools like the Sensory Profile to report an incidence of "sensory processing disorder." It is apparent that atypical scores on this assessment may indicate co-morbid issues that are interwoven with a number of other behavioral and social and psychiatric diagnostic constructs.
The prevalence concern may be even more significant. Claims about prevalence (Ahn, Miller, Milberger, and McIntosh, 2004; Ben-Sasson, Carter, and Briggs Gowan, 2009) of a proposed 'sensory processing disorder' have to be reconsidered in context that the Dunn Model may not adequately parse out sensory concerns from temperament concerns. Again, this is something that many clinicians have known for a very long time but this study validates those opinions.
The reality is that significant damage is done when non-validated or non-replicated research is rushed into clinical practice. One can only speculate on the efforts that will be required to unwind these notions that turn out to be only partially correct.
There are other important issues raised in the Su and Parham (2014) study. The authors state that one of their primary interests was to "test the discreteness of sensory system measures in preparation for further research examining whether functions of the tactile, vestibular, and proprioceptive systems serve as a foundation for visual and auditory functioning, as Ayres theory proposes." I do not understand why occupational therapists are still interested in applying hierarchical models to describe complexities of neurobehavioral function. For over 25 years that I have been studying and lecturing on sensory processing concerns I have left out hierarchical models because of all the research that has been done that supports heterarchical organization. There is simply too much research to even begin making citations, but descriptions of heterarchical neural organization can be found across all disciplines from neurology to psychology to robotics and computer engineering. As a primer into the notion of heterarchy and multilevel cross-disciplinary understanding of neurobehavioral concerns I recommend any of the articles written by Berntson and Cacioppo (seminal articles on heterarchy and social neuroscience referenced below).
Even if we can discretely reduce processing concerns into modality-specific categories, where is this going to lead us? It is very difficult to understand why occupational therapists continue to be interested in sensory-level intervention strategies when we have had such historic challenge with finding strong evidence for this kind of treatment approach. In contrast, other disciplines are developing evidence based cognitive-behavioral methods for addressing regulatory problems or for mediating stress-level responses. As an example I refer to research being conducted by Stanley (2009) that is being applied in a military context but that I suspect will be gaining much broader consideration due to the raw effectiveness of the techniques.
In summary, the Su and Parham (2014) study provides many interesting discussion points for occupational therapists who are interested in sensory processing and resultant behaviors. It is promising to see that there is some progress in our research that validates concerns that have been expressed by practitioners. However, there is evident need that as a profession we need to continue questioning our basic premises. So many other professions have moved beyond models of hierarchical organization, now embrace hetararchical and dynamic systems explanations for behavior, and are in the process of validating alternate non-sensory based intervention methods. Reading the literature of other disciplines provides strong evidence that occupational therapists are not at the forefront of relevancy on ideas about sensory processing and regulation.
Ahn, R. R., Miller, L. J., Milberger, S., and McIntosh, D. N. (2004). Prevalence of parents’ perceptions of sensory processing disorders among kindergarten children. American Journal of Occupational Therapy, 58, 287–293
Ben-Sasson, A., Carter, A.S., and Briggs Gowan, M.J. (2009). Sensory over-responsivity in elementary school: prevalence and social-emotional correlates. Journal of Abnormal Child Psychology, 37, 705-716.
Berntson, G.G., Boysen, S.T. and Cacioppo, J.T. (1993). Neurobehavioral organization and the cardinal principle of evaluative bivalence, Annals of the New York Academy of Sciences, vol. 702, pp. 75–102.
Cacioppo, J.T., Berntson, G.G., Sheridan, J.F., and McClintock, M.K. (2000). Multilevel integrative analyses of human behavior: Social Neuroscience and the complementing nature of social and biological approaches. Psychological Bulletin, 126(6), 829-843.
Dunn, W. (2001). The sensations of everyday life: Empirical, theoretical, and pragmatic considerations. American Journal of Occupational Therapy, 55, 608-622.
Shea, C. and Wu, R. (2013). Finding the Key: Sensory Profiles of Youths Involved in the Justice System. OT Practice 18(18), 9–13.
Stanley, E.A. and Jha, A.P. (2009). Mind Fitness: Improving operational effectiveness and building warrior resilience. Joint Force Quarterly, 55.4, 144-151.
Su, C. and Parham, D. (2014). Validity of sensory systems as distinct constructs, American Journal of Occupational Therapy, 68, 546-554.