title: Repeated Assessment and Practice Effects of the Written Symbol Digit Modalities Test Using a Short Inter-Test Interval.
abstract: The Symbol Digit Modalities Test (SDMT) is a widely used instrument to assess information processing speed, attention, visual scanning, and tracking. Considering that repeated evaluations are a common need in neuropsychological assessment routines, we explored test-retest reliability and practice effects of two alternate SDMT forms with a short inter-assessment interval. A total of 123 university students completed the written SDMT version in two different time points separated by a 150-min interval. Half of the participants accomplished the same form in both occasions, while the other half filled different forms. Overall, reasonable test-retest reliabilities were found (r = .70), and the subjects that completed the same form revealed significant practice effects (p < .001, dz = 1.61), which were almost non-existent in those filling different forms. These forms were found to be moderately reliable and to elicit a similar performance across participants, suggesting their utility in repeated cognitive assessments when brief inter-assessment intervals are required.
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal.
authors.forename: Diana R
authors.initials: DR
authors.lastname: Pereira
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal.
authors.forename: Patrício
authors.initials: P
authors.lastname: Costa
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal jcerqueira@ecsaude.uminho.pt.
authors.forename: João J
authors.initials: JJ
authors.lastname: Cerqueira
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests / Q000592:standards*; D011214:Practice, Psychological; D011597:Psychomotor Performance / Q000502:physiology*; D015203:Reproducibility of Results; D013997:Time Factors; D055815:Young Adult
keywords: Alternate forms; Practice effects; Repeated assessment; SDMT; Test–retest reliability