A growth curve model of learning acquisition among cognitively normal older adults

Abstract

The objective of this study was to model recall and learning on the Auditory Verbal Learning Test using latent growth curve techniques. Participants were older adults recruited for the ACTIVE cognitive intervention pilot. A series of nested models revealed that an approximately logarithmic growth curve model provided optimal fit to the data. Although recall and learning factors were statistically uncorrelated, a fitted multivariate model suggested that initial recall was significantly associated with demographic characteristics but unrelated to health factors and cognitive abilities. Individual differences in learning were related to race/ethnicity, speed of processing, verbal knowledge, and global cognitive function level. These results suggest that failing to recognize initial recall and learning as distinct constructs clouds the interpretation of supraspan memory tasks.

Figure 1

Path diagrams and parameterization details for different learning curve–fitting models. Observed variables (words recalled at successive AVLT trials) shown in rectangles, latent variables capturing random growth model parameters shown as ovals. Free parameters indicated with asterisks (*), fixed parameters shown to their numerical value. Parameters not illustrated are fixed to 0. Mean structures for growth model parameters shown in square brackets. See text for additional detail on model building.