Avoiding the recent past: Which stimulus dimensions influence proactive interference?

Abstract

Proactive interference occurs when information from the past disrupts current information processing, leading to confusion and forgetting in short-term memory. Popular theories of proactive interference include activation strength and similarity-based competition; however, these theories may not provide a comprehensive explanation of interference. This dissertation examines the possibility that additional factors may be involved in the creation of interference within the context of short-term memory (STM). Specifically, it investigates the hypothesis that recent information will interfere with current processing if it is similar to the current item along a task-relevant dimension. Chapter 2 investigates this possibility by manipulating the task being performed (using the recent probes task (a short-term memory recognition task) and a semantic- or perceptual-judgment categorization task, Experiments 1, 2, and 3) and dimensions of similarity irrelevant to the current task (perceptual similarity within the recent probes task, Experiments 4 and 5). Chapter 3 further investigates the possibility that the level of difficulty of the task may influence whether task-irrelevant similarity will create proactive interference; specifically, training is used to reduce the difficulty of perceptual-judgments found in Chapter 2, Experiment 2. Finally, Chapter 4 expands on the findings of the previous chapters, establishing a double dissociation between task-relevance and dimension of similarity by manipulating color and number-identity information within a 1-back short-term memory task. Results suggest that activation strength and similarity-based competition theories, though attractive, are not comprehensive explanations of proactive interference: instead, interference occurs within STM when items are similar to one another along a task-relevant dimension.