Modeling learning and memory using verbal learning tests: results from ACTIVE

Abstract

Objective: To investigate the influence of memory training on initial recall and learning.

Method: The Advanced Cognitive Training for Independent and Vital Elderly study of community-dwelling adults older than age 65 (n = 1,401). We decomposed trial-level recall in the Auditory Verbal Learning Test (AVLT) and Hopkins Verbal Learning Test (HVLT) into initial recall and learning across trials using latent growth models.

Results: Trial-level increases in words recalled in the AVLT and HVLT at each follow-up visit followed an approximately logarithmic shape. Over the 5-year study period, memory training was associated with slower decline in Trial 1 AVLT recall (Cohen's d = 0.35, p = .03) and steep pre- and posttraining acceleration in learning (d = 1.56, p < .001). Findings were replicated using the HVLT (decline in initial recall, d = 0.60, p = .01; pre- and posttraining acceleration in learning, d = 3.10, p < .001). Because of the immediate training boost, the memory-trained group had a higher level of recall than the control group through the end of the 5-year study period despite faster decline in learning.

Discussion: This study contributes to the understanding of the mechanisms by which training benefits memory and expands current knowledge by reporting long-term changes in initial recall and learning, as measured from growth models and by characterization of the impact of memory training on these components. Results reveal that memory training delays the worsening of memory span and boosts learning.

Figures

Figure 1.

Structural equation model diagram for a second-order latent growth model. Observed trial-level word-recall sums (T1–T5) are shown in squares and latent variables are shown in circles. Initial recall captures recall on the first trial at each study visit. The learning curve captures the number of words recalled between the first and fifth trials, and follows the same approximately logarithmic shape at each study visit. Intercepts for each of these parameters capture baseline values. Pre-and posttraining parameters capture the immediate effects of training and loading at posttraining to fifth-year time points with unit weight. Learning curves capture the annual change in the trial growth parameters, loading with fixed time steps reflecting years from baseline. The structural equation model for the HVLT is identical to this one, except there are only three trials per administration (T1–T3). Latent variable intercepts and slopes capturing change over time were regressed on covariates, which included age, sex, ethnicity, self-rated health, and education. Residual error variances are shown by smaller arrows going toward the observed (boxed) variables. Numbers on arrows going from latent growth parameters to observed time points are factor loadings.

Figure 2.

Longitudinal trajectories of AVLT recall and learning: Results from ACTIVE (n = 1,401). Graphic results from a multiple-group second-order latent growth model of trial-specific AVLT recall over time. Trial-specific growth was modeled as an approximately logarithmic trajectory. Dashed line: control group; solid line: memory-trained group; dotted lines: reference lines (estimated mean recall for controls on the first and final trials at the baseline study visit).

Figure 3.

Longitudinal trajectories of HVLT recall and learning: Results from ACTIVE (n = 1,401). Graphic results from a multiple-group second-order latent growth model of trial-specific AVLT recall over time. Trial-specific growth was modeled as an approximately logarithmic trajectory. Dashed line: control group; solid line: memory-trained group; dotted lines: reference lines (estimated mean recall for controls on the first and final trials at the baseline study visit).