New perspectives on iconic memory

The early stages of the human memory system for visual information are most commonly postulated to consist of iconic memory (a short-lived store with a high capacity) and visual short-term memory (a longer lasting store with a limited capacity). In addition to rapid registration of visual information, it has also been suggested that there is rapid registration of higher-level or semantic information about visual stimuli. However, the relationship between rapid registration of visual and semantic information across the early stages of memory requires further investigation. This thesis reports three empirical studies that investigated the nature of visual and semantic representations in the early stages of memory. The first study used a partial-report task with pictures of objects to investigate the nature of visual and semantic information accessible in the early stages of memory and how this information persists over time. The second study explored the effects of visual interference on access to early visual and semantic representations. The third study investigated the nature of memory representations across several early stages of memory in a change detection task. Memory performance indicated that visual and semantic representations could be accessed rapidly. Visual representations were initially more accessible than semantic representations but they were also more susceptible to decay. Visual representations were more susceptible than semantic representations to interference from subsequent visual information. Change detection was facilitated by visual and semantic cues and it deteriorated gradually as cues were delayed. The findings from these studies were used to evaluate existing accounts of iconic memory and the role of early stages of visual memory in rapid registration of new information.