The Effects of Acquisition and Test Conditions on Declarative and Motor-Procedural Memory for Complex Tools

Previous research revealed that the acquisition and retention of various tool properties (e.g., recalling information about a tools attributes, performing tool-related motor actions, demonstrating a tools correct use) requires complex cognitive processes, including declarative and motor-procedural memory. Though certain properties may rely more heavily on one type of memory than another, evidence indicates that various aspects of tool use may be mediated by an interaction between both memory systems. Given the possibility of flexible interactions between declarative and motor-procedural memory, this dissertation examined the effects of acquisition and test conditions on learning and retention of different tool properties, and the relative contributions of underlying memory processes. In Experiment 1, participants with Parkinsons disease (PD) (who had impaired striatal processing and motor-procedural memory but intact declarative memory), as well as healthy controls, demonstrated that completing additional, massed practice trials enhanced motor acquisition performance and overall learning across sessions. However, retention differed between the two groups: healthy controls, but not PD participants, retained their motor performance across 1-day and 3-week delays. Additional practice also resulted in superior recall of tool attributes across participants, indicating enhanced declarative memory with a greater number of training trials. In Experiment 2, the effects of practice schedules were examined in a sample of healthy adults. Findings demonstrated support for the spacing effect, such that compared to massed practice (i.e., consecutive trials), spaced practice improved test performance on all tool properties after a 3-week delay, indicating enhanced declarative and motor-procedural memory. The interaction between spacing and learning type (i.e., observation vs. practice) was examined in Experiment 3. Results showed that for tool properties mediated primarily by declarative memory, spacing effects were observed after a 3-week delay at test, regardless of whether participants observed or physically practiced the task during acquisition. However, for properties that were heavily mediated by motor-procedural memory, there were no spacing effects with observational learning. These findings demonstrated that underlying memory system must be considered when assessing spacing effects, such that the learning method must successfully engage the underlying memory system in order for spacing to be effective. Taken together, my pattern of results across studies revealed that both declarative and motor-procedural memory likely contributed to performance across various tool properties. However, the manipulation of key acquisition parameters affected how these two memory systems facilitated performance, which ultimately impacted performance after a 3-week delay. Retention findings also demonstrated that test conditions may influence the contributions of declarative and motor-procedural memory. Together these experiments provide further insights about cognitive processes underlying tool use, as well as about flexible interactions between memory systems.