Visual perception is an essential aspect of one's ability to mentally manipulate visual information in order to solve and respond to problems (Kurtz, 2006). Visual perception, therefore, facilitates one's overall performance capacity in regards to safely and independently performing self care tasks and participating in work/leisure related activities (Cooke, McKenna, Fleming, & Darnell, 2006; Erhardt & Duckman, 1997; Scheiman, 1997a). Unfortunately the complexity of the human visual system renders it "vulnerable to many dysfunctional skills which can severly impact its effectiveness as an information processing tool" (Su, Chein, Chen, & Lin, 1995, p. 3).
Consequently, occupational therapists routinely assess visual perception, particularly when working with clients who present with pre-existing clinical conditions commonly associated with visual perceptual dysfunction (American Occupational Therapy Association, 1991, 2008; Canadian Association of Occupational Therapists, 1990). Diagnoses that are often associated with visual perceptual dysfunction include: multiple sclerosis, dementia, cerebral palsy, Parkinson's disease, cerebrovascular accident, and aquired brain injury (Bouska et al., 1990; Edmans, Towle, & Lincoln, 1991; Glosser, Gallo, Duda, de Vries, Clark et al., 2002; Kozeis, Anogeianaki, Mitova, Anogianakis, Mitov, et al. 2007; Lezak, 1995; Mercier, Audet, Hebert, Rochette, & Dubois, 2001; Neistadt, 1990; Ogden, 1990; Unsworth, 1999; York & Cermak, 1995).
Three tests that are commonly used by American healthcare professionals to assess adult visual perception are the Developmental Test of Visual Perception -Adolescent and Adult (DTVP-A; Reynolds, Pearson, & Voress, 2002), the Motor-Free Visual Perceptual Test--3rd edition (MVPT-3; Colarusso & Hammill, 2003), and the Test of Visual Perceptual Skills (non-motor) 3rd edition (TVPS-3; Martin, 2006). Each of these tests was developed in the United States (US) and emerged from revisions made to pre-existing, paediatric test editions (Colarusso & Hammill, 1972, 1996, 2003; Gardner, 1982, 1992; Hammill et al., 1993; Martin, 2006; Reynolds et al., 2002).
As the DTVP-A, MVPT-3, and TVPS-3 are commonly used outside the US, it is essential to assess their psychometric properties in other cultural contexts (Bishop & Curtin, 2001; Burtner, Whilhite, Bordegaray, Moedl et al., 1997; Grieve & Gnanasekaran, 2008; Rodger, 1994). Consequently, the authors of this study deemed it important to investigate whether tests developed and standardised within one country operate in a similar manner in other countries. For example, if a test contains certain items that are meaningful and relevant within one cultural environment but not in another, then respondents answering test items might be disadvantaged by answering the test items incorrectly. In other words, the test scores of respondents from cultural environments other than the one in which the test was originally developed might not be truly reflective of their abilities and skills. Hence the aim of this study is to investigate the discriminative validity of these three visual perceptual tests.
Very few peer-reviewed studies have adopted this focus (Canivez, 2005; Hodgson, 2005; King, 2005). Therefore this study investigated the DTVP-A, MVPT-3, and TVPS-3 in an Australian context by comparing the performance of two groups, one group of individuals diagnosed with a neurological impairment and one group with no known impairment, according to these three tests. This study also investigated the ability of the DTVP-A, MVPT-3, and the TVPS-3 to successfully discriminate between two groups of participants with a known difference, those being with and without a diagnosed neurological impairment.
The literature review provides an overview of visual perception, the subtypes of visual perception that have been identified in the empirical literature, and the impact of visual perception dysfunction on the occupational performance of individuals. …