On visual sensory memory for natural scenes

What high-level representations of natural scenes (e.g. object identity and scene categorization, or gist) are stored in visual sensory (iconic) memory? Previous studies have demonstrated a high-capacity but fleeting memory for low-level features, such as color, orientation and motion as well as overlearned alphanumeric characters and isolated objects. The studies reported here investigated whether such a rich memory exists for semantic aspects of a briefly presented natural or real-world scene. The first study looked at whether iconic memory exists for objects contained in natural scenes. Using a modified change detection task, we found that, indeed, iconic memory does support object identification in such scenes even as long as 1000 msec after stimulus offset. In a second study, we explored the role of the gist or the category of the scene on reporting gist-related and gist-unrelated objects from an iconic memory of the stimulus. Here, we found no evidence that the gist of the scene facilitated report of objects from iconic memory. In a final study, we asked whether the gist of multiple scenes is contained in iconic memory. The results of this experiment suggest that iconic memory contains more information about scene gist than is contained in visual short-term memory. The combined results of this research suggest that more high-level semantic information (specifically, object identity and scene gist) is contained in iconic memory than has previously been demonstrated. Implications for consciousness and visual perception are discussed.