Wednesday, October 23, 2013, 10:00am – 11:00am, in 489 Minor Hall

Visual Working Memory: From Limited Resources to Neural Codes

presented by

Paul Bays, Ph.D.
Wellcome-Beit & Career Development Fellow
University College London Institute of Neurology

 

Visual short-term memory works in harmony with shifts of attention and eye movements to produce the illusion of a seamless representation of our visual environment. However, visual memory capacity is extremely limited. This limit has classically been thought of as 3 or 4 independent memory ‘slots’ each holding a single visual object. Contrary to this conventional model, I will argue that storage in visual memory is a highly flexible process, in which a unitary working memory resource is continuously and dynamically distributed between objects in the environment. Each eye movement is accompanied by a re-allocation of resources and an updating of memory contents, in which visual information from the preceding fixation is integrated with the new input. A possible biological basis for the limited resource can be found in neural population coding, and I will show that errors associated with decreasing signal strength in probabilistically spiking neurons reproduce the pattern of failures in human recall under increasing memory load. Observers prioritize accurate storage of behaviorally-relevant information, at a cost to lower priority stimuli, and I will show that this trade-off is achieved in a near-optimal manner under the constraints of neural noise.

 

Host: Michael Silver

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