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CCN Brown Bag Series

Wednesday, November 29, 2017,
  • Location: Wilson Hall • 111 21St Ave S • Nashville, TN 37240
  • Room: 115

Joe Lappin, PhD

Department of Psychology

Vanderbilt University

The Channel Capacity of Visual Awareness

We know less than meets the eye.  Observers often fail to notice salient information even when it is entirely visible in the field of view.  Such failures of awareness are caused chiefly by attention to competing information.  Limited capacity is an essentially axiomatic correlate of visual attention, but the nature of that capacity is often unspecified and unquantified.  

Analyses of response times for visual target detection recently identified and quantified a channel capacity for visual awareness— measurable in bits/s.  Shannon’s (1948) Fundamental Theorem states that any given communication channel has a maximum rate of transmission, which is imposed by the maximum rate of variation in its physical states.  Thus, the brain mechanism of conscious visual awareness may operate at a similarly limited rate.  In support of this idea, Lappin, Morse, & Seiffert (2016) discovered that conscious awareness and detection of visual target motions occurred at a rate that was invariant with both the quantity of input information and the speed of output responses.  Moreover, the process of awareness operated in parallel with visual integration of motion signals, concurrently and independently. 

Recent experiments have expanded this investigation with more predictable spatiotemporal patterns, sudden changes in visual information, and more difficult detection tasks.  The methods and results point to a general theory of visual awareness