Construct validity and reliability of working memory tasks for people with aphasia

Abstract

Background: Although several studies have examined working memory in people with aphasia, there is little information about the psychometric properties of tasks used to measure working memory in this population.

Aims: The aims of this study were (1) to examine the construct validity, internal consistency, and test-retest reliability of several working memory tasks and (2) to determine which tasks were feasible to use with people with a wide range of aphasia severities.

Methods & Procedures: In experiment one, non-brain-damaged adults (n = 47) completed a set of working memory tasks that were designed for use with people with aphasia. The tasks included 1-back, 2-back, listening span and forward and backward versions of picture span and square span. Construct validity was assessed by correlating performance on the new tasks with a composite score based on three well-established working memory tasks with known psychometric properties. Ten older adults completed the testing battery twice to measure test-retest reliability. Internal consistency was estimated using split-half reliability. In experiment two, people with aphasia (n = 12) completed the new working memory tasks.

Outcomes & Results: The picture span tasks demonstrated acceptable test-retest reliability, internal consistency, and construct validity. Controls showed ceiling effects on 1-back and people with aphasia showed floor effects on listening span. Both the square span tasks and n-back showed poor internal consistency for people with aphasia and age-matched controls.

Conclusions: A composite score based on the forward and backward versions of picture span provides a measure of verbal working memory with acceptable construct validity, internal consistency and test-retest reliability and can be completed by non-brain-damaged adults and people with aphasia.

Keywords:

• Aphasia
• Working memory
• Construct validity
• Test-retest reliability
• Split-half reliability

We would like to thank the research participants and their families and the students who helped with data collection. We also thank Heather Wright and Stephanie Christensen for kindly providing their n-back task for use in this study, and Cindy Thompson for sharing her version of listening span with us.