He served on the US National Research Council's Committee on Vision.
Among Shapley's findings were his discoveries about the X and Y retinal ganglion cells in the cat retina.
He discovered that the Y cell collected excitatory signals from many small spatial mechanisms called "nonlinear subunits"[3] and that there was a contrast gain control, a nonlinear feedback within the retina that adjusted the signal-transfer properties of the retina contingent on the space-averaged stimulus contrast.
[8] Other findings that have elucidated the workings of V1 include the following: V1 cells are tuned for color and for spatial pattern;[9][10][11] fluctuations in the local field potential in V1 appear to be caused by noise and have no autocoherence or phase-memory over time;[12][13] and there is not a single fixed cortical receptive field for each neuron.
[14] More recently, he has been studying how color is represented in the visual cortex, as a follow-up to his earlier work on parallel pathways for color and brightness contrast in the retina.