Sensory processing problems can often negatively impact on a child's occupational performance. For example, the limited range of foods a child will eat, sensitivity to certain types of clothing textures, low tolerance for noisy environments, and aversion to being hugged. Occupational therapists have a key role in assessing the sensory needs of children. Sensory processing scales used with school-age children include the Sensory Profile (Dunn, 1999), the Sensory Profile School Companion (SPSC) (Dunn, 2006), and the Sensory Processing Measure (SPM) (Miller-Kuhaneck, Henry, Glennon, & Mu, 2007; Parham, Ecker, Miller-Kuhananeck, Henry, & Glennon, 2007). These scales are all standardized parent-report, teacher-report, judgment-based questionnaires that require the respondent to complete a rating scale based on how frequently certain behaviours occur. For any standardized test, it important that a body of psychometric evidence is established, particularly studies completed by independent investigators, in addition to the studies completed by the original test authors (Anastasi & Urbina, 1997; Downing, 2003; Streiner & Norman, 1995). Since the scales under investigation are all relatively new, additional empirical studies documenting their reliability and validity are needed (Baranek, 2002; Goodwin, 2002; Kielhofner, 2006).
The purpose of this study is to examine the convergent validity of the Sensory Profile, the SPSC, and the Home and Main Classroom Forms of the SPM. The specific research questions are: i) what is the convergent validity of the SPM--Home Form and the Sensory Profile?; ii) what is the convergent validity of the SPM--Main Classroom Form and the SPSC?; and iii) what is the association between the ratings of mothers of children who complete the Sensory Profile and the SPM--Home Form and the ratings of teachers of the same children who complete the SPSC and the SPM--Main Classroom Form?
The Sensory Profile, the SPSC, and the SPM were all developed in the United States, but are used by therapists in New Zealand and Australia as well as other Western countries (Rodger, Brown, & Brown, 2006; Rodger, Brown, Brown, & Roever, 2006). Completing studies in a cross cultural context provides valuable data about the relevance, usability, and applicability of the scales (Brown, Leo, & Austin, 2008; Streiner & Norman, 1995). Information regarding convergent validity is currently lacking with the Sensory Profile, SPSC, and the SPM (Fairbank, 2005; Miller-Kuhaneck et al., 2007).
Sensory processing is a neurological process that occurs in all of us. Sensory input from the environment and from the body itself provides information to the brain (Dunn, 2007). The brain organizes, integrates, synthesizes, and uses this information to understand experiences and organize appropriate responses. The processing of information allows individuals to respond automatically, efficiently, and comfortably in response to the specific sensory inputs received (Dunn, 2007; Yack, Aquilla, & Sutton, 2002). Sensory processing skills influence a child's ability to perform everyday tasks and activities (occupations), and therefore they are used by occupational therapists for specific assessment, intervention, monitoring, and follow-up evaluation (Case-Smith, Richardson, & Schultz-Krohn, 2005; Yack et al., 2002).
Sensory processing disorder
Sometimes a child's response to the sensory environment can have a negative impact on the successful engagement with and completion of his/her daily life occupations. Sensory processing disorders (SPD) "affects the way the brain interprets the information that comes in and the response that follows, causing emotional, motor, and other reactions that are inappropriate and extreme" (Bowyer & Cahill, 2009, p. 331). Reduced ability to play successfully with other children can be related to poor participation in sensory and motor play, from which cognitive and social skills emerge and develop (Bundy, 2002). The fear, anxiety, or discomfort experienced in everyday situations by children with sensory processing impairments can disrupt daily routines in the home environment (Parham & Mailloux, 2005). Furthermore, school environments may contain social and physical stimuli that cause these children distress (Burleigh, McIntosh, & Thompson, 2002). Challenges stemming from sensory processing disorders sometimes only become apparent once a child enters a day-care or school environment (Burleigh et al.). Sensory processing problems may even persist into adulthood, with related social, behavioural, and emotional difficulties (Kinnealey, Oliver, & Wilbarger, 1995).
Parham and Mailloux (2005) outlined five functional impairments associated with SPD. These include, decreased social participation and occupational engagement; decreased length, frequency, or complexity of adaptive responses (successful response to an environmental challenge); impaired self-confidence and or self-esteem; poor daily life skills and reduced family life; and diminished fine-, gross-, and sensory-motor skill development. SPD can negatively affect development and functional abilities in behavior, emotional, motor, and cognitive domains (Ahn et al., 2004). Children diagnosed with various conditions including Autism Spectrum Disorder, Asperger Syndrome, Attention Deficit Hyperactivity Disorder, Sensory Modulation Disorder, Developmental Coordination Disorder to name a few, are prone to SPD (Ahn et al.; Baranek, 2002; Dunn, 2006; Kern et al., 2007; Reebye & Stalker, 2008; Rogers, Hepburn, & Wehner, 2003). Occupational therapists working with children in these diagnostic groups, aim to promote and optimize their occupational performance and occupational development, therefore they need to assess and understand sensory processing.
Estimated rates of sensory processing disorders for children with developmental disabilities have been derived from reliable and valid survey results and are reported to be as high as 40% to 88% (Tomchek & Dunn, 2007). Among children without disabilities, estimates of the prevalence of sensory processing disorders based on clinical experience have ranged from 5% to 10% (Ahn et al., 2004). However, no prospective published data exists on the rate of sensory processing disorders in a typically developing population. Ahn et al. conducted one such study, to estimate sensory processing disorders in a typically developing population, using a parent-report survey screening instrument. This study found that 5.3% of their sample met criteria for SPD. These figures clearly indicate the importance of having instruments and scales that are valid and reliable when screening and assessing sensory processing issues.
The validity of a test or scale is gauged by comparing it to tests of the same concept or construct developed through other methods (Streiner & Norman, 1995). The convergent validity of an instrument or scale indicates the degree of consistency between measurements obtained by different approaches measuring the same trait (Anastasi & Urbina, 1997). For instance, to demonstrate the convergent validity of a test of reading skills, two sets of scores from different tests measuring the same reading ability would be compared. High correlations between the test scores would be evidence of a convergent validity between the two instruments. To estimate the degree to which any two scales are related to each other, a correlation coefficient is typically used (Anastasi & Urbina). That is, the patterns of inter correlations among the test scores …