The effect of interference and time on forgetting in visual short-term memory

Abstract

‘Memory’ is a flexible cognitive system, adapting to suit the specific needs of the individual. Creating and losing memories helps to maintain the harmony of a complex set of neurological processes. However, the reason for losing memories has led to a contentious debate, especially in short-term memory. Theories based on temporal decay, temporal distinctiveness, interference or consolidation offer the main explanations for the phenomenon of forgetting, but the debate concerning these theories is fiercely argued. This project designed and developed a new methodological approach to understand the effects of time on very short-term memory and test the four major forgetting theories. The method was developed over six experiments and the main task was built around encoding visual stimuli presented in two or three blocks. After all stimuli had been displayed, there was a recognition task, but primary interest was in the second block. The delay between blocks was varied, to assess the effect of a pre-learning break (the delay separating blocks 1 and 2) and a post-learning break (the delay separating blocks 2 and 3, or block 2 from recognition). Stimuli were either unfamiliar, abstract shapes (Experiments 1-3) or photos of meaningful items (Experiments 4-6), Overall findings showed the effect of time on visual memory to be complex. However, generally there was evidence for longer delays leading to better performance, although this did depend on specific methodological parameters. The findings did still challenge traditional interference-based theories and temporal distinctiveness models emerged as the best account for the current findings.