Hyperacuities

The common model of hyper acuities that I am familiar with talk about interpolation of the blur circle across several receptive fields (Westheimer, 1979).  However, with spatial summation across several receptors even in the fovea, is this still possible to be reconstructed.  the interactive chart is the results of a test of our ability to perceive hyperacuities after the spatial summation of the LGN.  The chart shows the differences between two ganglion cell outputs when the input is identical but outset by about 1/5th of a cone, which is roughly the size of our vernier threshold in the fovea relative to the cone size (Westheimer, 1979).  Notice that the differences in the two outputs seem to be of substantial size.  The two sets of bars represent situations where the either the optical blur due to spherical aberration and diffraction are simulated at the edges (burgundy bars) or not (blue bars).  Notice that the outputs are nearly identical showing that the summation at the ganglion cells is one way that can act to minimize the effects of spherical aberration on our perceptions.. 

You can change the size of the receptive fields above as in the other charts.  Notice that as you increase the size of the central and surround regions the ability to detect the difference in position.  However, it seems clear that great positional sensitivity is maintained through the receptive fields.  In other words, this type of spatial summation lets us know where something is.  The filtering is much more on the size of what can be perceived than on where it is.