Detection of displacement during saccades: spatial and functional differences allied to preprogramming

An experimental group of subjects was required to make two saccades to a series of defined points; during the first, either the target for the second, or a point irrelevant to the second, was displaced A control group saw identical displays and displacements but made only one saccade; for them, all displaced points were irrelevant to the saccade. No differences in detection between the groups were found for an irrelevant point, but for the target point clearly lower detection rates and higher rates of misattribution occurred in the experimental group. Displacements of the point next to the target were also harder to detect for the experimental group but were less likely to be misattributed. These results can be interpreted as a perceptual stabilisation of the target for a second saccade (its adoption as a frame of reference) even during a prior saccade, and they are compatible with the preprogramming of the second saccade.