The Limited Role of Attention in the Production Effect: Converging Evidence from Behavioural and Computational Methods

Abstract

Encoding techniques can enhance memory and may serve as a means of protection from the negative effects of multitasking on memory. The production effect refers to the reliable memory advantage observed when words are spoken aloud rather than silently during the encoding phase for a list of words. This thesis examined the effectiveness of production in boosting memory, even when encoding is performed under divided attention (DA) conditions. In so doing, I expand its potential benefit into a different context, while also specifying whether the availability of attention influences the magnitude of the effect. In Experiment 1, conducted online using the recruitment platform Prolific, participants were visually presented, in counterbalanced order, with two 20-item lists of words: one under full attention (FA) and another under DA with a concurrently performed auditory digit-monitoring task. Within lists, half of the words were prompted to be read aloud, and half were read silently. Memory was subsequently assessed based on the number of correctly recalled words, retrieved via free recall. As expected, memory was lower overall following DA than FA, but importantly, the relative benefit to memory for words read aloud at encoding was maintained. Experiment 2 replicated this pattern using an in-person sample. These results suggest a limited role of attention on the production effect. In Chapter 3, I aimed to develop a computational model that could mimic existing human data of the production effect and findings from Experiment 1. I employed Nengo, a Python package for building, testing, and deploying spiking neural networks. I used this computational tool to simulate human performance. Two sets of words were presented to the model, one under FA and the other under DA: “read aloud” words (half within each list) were reinforced during initial encoding via increasing item strength by 90%, while words “read silently” were not reinforced. We simulated DA during the encoding phase by destabilizing the model’s memory representation of each word through a reduction in the signal-to-noise ratio. Subsequently, recall was simulated using a competitive accumulation process, and output was measured separately by condition. Recall output from 50 unique simulations was compared to that of 50 human participants randomly selected from Experiment 1. In both human and model data, recall was higher for words read aloud than silently, with the general pattern preserved even under DA conditions; however, the magnitude of the production effect in the modelled data was reduced, likely due to floor effects as overall output was quite low following DA. The results of my thesis suggest that attention plays a limited role in accounting for production’s benefit to memory, with converging evidence provided from two methodologies.