The Reliability of Performance of Healthy Adults on Three Visual Perception Tests
Brown, Ted, Mullins, Erin, Stagnitti, Karen, British Journal of Occupational Therapy
Problems with visual perceptual skills have been shown to have a negative impact on the daily living skills of individuals and are, therefore, commonly assessed by occupational therapists. The purpose of this study was to examine two types of reliability (internal consistency and test-retest reliability) of three newly revised or developed adult visual perception tests. The participants were 50 healthy adults, aged 18 to 55 years, from Melbourne, Victoria, Australia. The participants completed the Developmental Test of Visual Perception--Adolescent and Adult (DTVP-A), the Motor-Free Visual Perception Test--Third Edition (MVPT-3) and the Test of Visual Perceptual Skills (non-motor)--Third Edition (TVPS-3). Internal consistency was examined using Cronbach's alpha calculations and test-retest
reliability was analysed using Spearman rho non-parametric correlation coefficients. The results indicated that the DTVP-A, the MVPT-3 and the TVPS-3 had total scale internal consistency correlation scores of 0.60 or higher (0.60, 0.69 and 0.63 respectively). The majority of the subscales of each test had lower correlation coefficients than the overall scores (ranging from 0.22 to 0.49). For the DTVP-A, MVPT-3 and TVPS-3 total scale scores, the test-retest reliability correlation coefficients were statistically significant (rho = 0.46, p<0.05; rho = 0.62, p<0.01; and rho = 0.59, p<0.01, respectively). Overall, the three visual perceptual tests exhibited low to moderate levels of internal consistency and test-retest reliability.
Key words: Visual perception, assessment, occupational therapy, internal consistency, test-retest reliability.
Occupational therapists frequently assess the visual perceptual abilities of adult clients since problems with visual perception have been shown to have a negative impact on the daily living skills of individuals (Cockburn et al 1990, Edmans et al 1991, Connor and Padula 2005). Visual perceptual dysfunction is commonly associated with clinical conditions involving a neurological disorder or an acquired injury, such as a cerebrovascular accident (Barer et al 1990, Jesshope et al 1991, Cherney et al 2001, Mercier et al 2001, Donnelly 2002), acquired brain injury (Neistadt 1990), dementia (Hill et al 1995, Glosser et al 2002), cerebral palsy (Bouska et al 1990), Parkinson's disease (Bouska et al 1990) or multiple sclerosis (Unsworth 1999). Therefore, occupational therapists often assess the visual perceptual skills of adults presenting with a neurological impairment.
Accuracy in the assessment of visual perception is dependent on the tests used by professionals possessing sound measurement properties, such as reliability. If an instrument has well established levels of reliability, professionals can use the test with confidence because it will provide a consistent and stable measure of clients' abilities, with little random error or influence from external factors (Benson and Schell 1997, Harris 2004, Richardson 2005, Kielhofner and Fossey 2006).
Three visual perceptual tests used with adults are the Developmental Test of Visual Perception--Adolescent and Adult (DTVP-A) (Reynolds et al 2002); the Motor-Free Visual Perception Test--Third Edition (MVPT-3) (Colarusso and Hammill 2003); and the Test of Visual Perceptual Skills (non-motor)--Third Edition (TVPS-3) (Martin 2006). The DTVP-A, the MVPT-3 and the TVPS-3 are all newly revised or developed motor-free tests of visual perception, with limited data published about their reliability (Busch-Rossnagel 1985, Denison 1985, Ryan 1988, Tindal 1995, Burtner et al 1997, Van Deusen and Brunt 1997, Volpe-Johnstone 2001, Asher 2007).
All three visual perceptual tests were originally developed for use with children and were subsequently standardised for use with adults. The DTVP-A is an adolescent and adult version of the Developmental Test of Visual Perception, 2nd edition (Hammill et al 1993). …