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People/Faculty
Mary C. Potter, Ph.D.
Professor of Psychology

Department of Brain and Cognitive Sciences
Building: 46-4125
Lab: Mollylab
Email: mpotter@mit.edu

Cognitive Processes: Attention, Perception, Comprehension and Memory
The overall goal of research in the Potter laboratory is to understand the very rapid processes involved in perceiving, comprehending, and remembering meaningful material such as words, sentences, or pictures. In contemporary theories of human information processing, such material passes through several stages of analysis as it is perceived and understood, and it is these stages and their interactions that we investigate.

A key discovery is that understanding the meaning of a pictured scene or written word happens in a fraction of a second, much faster than the time required for stabilizing even a brief memory of that stimulus. The viewer may not even become conscious of the stimulus unless it fits in with the context. For example, the lab has shown that a sentence can be understood and remembered when presented as rapidly as 12 words per second (using RSVP, rapid serial visual presentation). In contrast, a sequence of unrelated words (even if no longer than 4 or 5 words) is much more difficult to process and few are remembered. Similarly, viewers can pick out a target picture from a rapid sequence when given a title such as "a picnic," although they cannot remember most of the pictures they have just seen. In recent work we have found, however, that memory for the pictures persists briefly, consistent with the idea that there is a conceptual short term memory (CSTM) for meaningful material. A question we are currently studying is whether this brief memory is primarily visual or primarily conceptual.

We also study competition for attention using words and other visual stimuli. When the viewer is looking for two targets in a stream of nontargets presented at 10/s, detection of the second target is markedly impaired when it arrives 200-500 ms of the first target, an attentional blink. We have shown that that at very short intervals it is the first target that is more likely to be missed. In contrast, when the task is to report all the items on a short list, there is no evidence of an attentional blink. The lab's work also encompasses other questions about perception, attention, memory, and language processing, including repetition blindness, the creative misperception of a nonword as influenced by semantic context, cross-modal (visual-auditory) processing of sentences, and the conceptual basis of "verbatim" recall of sentences. These studies contribute to our understanding of how a stimulus such as a word, sentence, or picture generates an interpretation and a fleeting or stable memory.

Potter, M. C. (2006). Competition for attention in space and time: The first 200 ms. In H. Ogmen & B. G. Breitmeyer (Eds.) The first half second: The microgenesis and temporal dynamics of unconscious and conscious visual processes. Cambridge , MA : MIT Press.

Nieuwenstein, M. R., & Potter, M. C. (2006). Temporal limits of selection and memory encoding: A comparison of whole versus partial report in rapid serial visual presentation. Psychological Science, 17 , 471-475.

Davenport , J. L., & Potter, M. C. (2004). Scene consistency in object and background perception. Psychological Science, 15 , 559-564.

Potter, M. C., Staub, A., & O'Connor, D. H. (2004). Pictorial and conceptual representation of glimpse pictures. Journal of Experimental Psychology: Human Perception and Performance, 30 , 478-489.

Potter, M. C., Dell'Acqua, R., Pesciarelli, F., Job, R., Peressotti, F., & O'Connor, D. H. (2005). Bidirectional semantic priming in the attentional blink. Psychonomic Bulletin & Review, 12 , 460-465.

Potter, M. C. (1999). Understanding sentences and scenes: The role of conceptual short term memory. In V. Coltheart (Ed), Fleeting memories: Cognition of brief visual stimuli . Cambridge : MIT Press.