Cognition test battery: Adjusting for practice and stimulus set effects for varying administration intervals in high performing individuals

Abstract

Introduction: Practice effects associated with the repeated administration of cognitive tests often confound true therapeutic or experimental effects. Alternate test forms help reduce practice effects, but generating stimulus sets with identical properties can be difficult. The main objective of this study was to disentangle practice and stimulus set effects for Cognition, a battery of 10 brief cognitive tests specifically designed for high-performing populations with 15 unique versions for repeated testing. A secondary objective was to investigate the effects of test-retest interval on practice effects.

Methods: The 15 versions of Cognition were administered in three groups of 15-16 subjects (total N = 46, mean±SD age 32.5 ± 7.2 years, range 25-54 years, 23 male) in a randomized but balanced fashion with administration intervals of ≥10 days, ≤5 days, or 4 times per day. Mixed effect models were used to investigate linear and logarithmic trends across repeated administrations in key speed and accuracy outcomes, whether these trends differed significantly between administration interval groups, and whether stimulus sets differed significantly in difficulty.

Results: Protracted, non-linear practice effects well beyond the second administration were observed for most of the 10 Cognition tests both in accuracy and speed, but test-retest administration interval significantly affected practice effects only for 3 out of the 10 tests and only in the speed domain. Stimulus set effects were observed for the 6 Cognition tests that use unique sets of stimuli. Factors were established that allow for correcting for both practice and stimulus set effects.

Conclusions: Practice effects are pronounced and probably under-appreciated in cognitive testing. The correction factors established in this study are a unique feature of the Cognition battery that can help avoid masking practice effects, address noise generated by differences in stimulus set difficulty, and facilitate interpretation of results from studies with repeated assessments.

Keywords: Cognition; learning; practice; test difficulty; testing interval.

Figures

Figure 1:. Changes in Cognition speed outcomes with repeated test administration.

Each subject performed the Cognition battery 15 times. A significant logarithmic trend was found for all tests but the Psychomotor Vigilance Test (PVT). Black dots represent estimated means relative to the overall mean across test administrations. Error bars reflect standard errors. The red line reflects a logarithmic trend line fitted to the estimated means. MP: Motor Praxis; VOLT: Visual Object Learning Test; F2B: Fractal 2-Back; AM: Abstract Matching; LOT: Line Orientation Test; ERT: Emotion Recognition Test; MRT: Matrix Reasoning Test; DSST: Digit Symbol Substitution Test; BART: Balloon Analog Risk Test; PVT: Psychomotor Vigilance Test

Figure 2:. Changes in Cognition accuracy outcomes with repeated test administration.

Each subject performed the Cognition battery 15 times. A significant logarithmic trend was found for 6 out of the 10 tests. Black dots represent estimated means relative to the overall mean across test administrations. Error bars reflect standard errors. The red line reflects a logarithmic trend line fitted to the estimated means. MP: Motor Praxis; VOLT: Visual Object Learning Test; F2B: Fractal 2-Back; AM: Abstract Matching; LOT: Line Orientation Test; ERT: Emotion Recognition Test; MRT: Matrix Reasoning Test; DSST: Digit Symbol Substitution Test; BART: Balloon Analog Risk Test; PVT: Psychomotor Vigilance Test

Figure 3:. Effect of test-retest administration interval on practice effects in the speed domain.

Each subject performed the Cognition battery 15 times with different test-retest intervals (Long (blue): ≥10 days; Short (black): ≤5 days; Ultrashort (red): four times per day with 15 minute breaks between tests). MP: Motor Praxis; VOLT: Visual Object Learning Test; F2B: Fractal 2-Back; AM: Abstract Matching; LOT: Line Orientation Test; ERT: Emotion Recognition Test; MRT: Matrix Reasoning Test; DSST: Digit Symbol Substitution Test; BART: Balloon Analog Risk Test; PVT: Psychomotor Vigilance Test

Figure 4:. Effect of test-retest administration interval on practice effects in the accuracy domain.

Each subject performed the Cognition battery 15 times with different test-retest intervals (Long (blue): ≥10 days; Short (black): ≤5 days; Ultrashort (red): four times per day with 15 minute breaks between tests). MP: Motor Praxis; VOLT: Visual Object Learning Test; F2B: Fractal 2-Back; AM: Abstract Matching; LOT: Line Orientation Test; ERT: Emotion Recognition Test; MRT: Matrix Reasoning Test; DSST: Digit Symbol Substitution Test; BART: Balloon Analog Risk Test; PVT: Psychomotor Vigilance Test

Figure 5:. Differences between stimulus sets in the speed domain.

Significant differences in Cognition speed performance across the 15 test versions were found for four out of the 10 Cognition tests. Black dots represent estimated means relative to the overall mean across test administrations. Error bars reflect standard errors. MP: Motor Praxis; VOLT: Visual Object Learning Test; F2B: Fractal 2-Back; AM: Abstract Matching; LOT: Line Orientation Test; ERT: Emotion Recognition Test; MRT: Matrix Reasoning Test; DSST: Digit Symbol Substitution Test; BART: Balloon Analog Risk Test; PVT: Psychomotor Vigilance Test

Figure 6:. Differences between stimulus sets in the accuracy domain.

Significant differences in Cognition accuracy performance across the 15 test versions were found for those six out of the 10 Cognition tests that have unique stimulus sets. Black dots represent estimated means relative to the overall mean across test administrations. Error bars reflect standard errors. MP: Motor Praxis; VOLT: Visual Object Learning Test; F2B: Fractal 2-Back; AM: Abstract Matching; LOT: Line Orientation Test; ERT: Emotion Recognition Test; MRT: Matrix Reasoning Test; DSST: Digit Symbol Substitution Test; BART: Balloon Analog Risk Test; PVT: Psychomotor Vigilance Test