Interpolation during apparent motion

A simple experiment was performed to demonstrate a spatiotemporal filling-in process in apparent motion. A vertical column consisting of seven closely spaced dots was presented in a sequence of eight discrete positions, except for the fifth position in which only part of the column (upper two dots) was shown. At an appropriate timing of this repeated sequence no partial gap could be discerned. A sequence of at least two complete columns on either side of the partial column is necessary for this filling-in to occur. This implies that the visual system must be integrating information over several frames and that the result of this computation influences the perception of subsequent spatially adjacent frames.