Is the increased spatial uncertainty in the normal periphery due to spatial undersampling or uncalibrated disarray?

There are two possible causes for the elevated positional uncertainty of the peripheral field; undersampling by post receptoral arrays or uncalibrated disarray within post receptoral arrays. In order to assess the relative influences of these two factors to peripheral spatial uncertainty, we apply an approach which has enjoyed much success in the field of colour vision to examine the trade-off between position and contrast errors for spatial vision. We show that, if our positional uncertainty in the periphery is due to spatial undersampling, a correlated contrast inaccuracy should be present. We find no evidence for this expected linkage in the peripheral field at any spatial scale. We conclude that uncalibrated neural disarray rather than undersampling is the cause of peripheral positional uncertainty.