There is ample neurophysiological evidence that vision establishes different frames of reference, gaze centered, head centered, body centered, and possibly others, combining them probabilistically for different tasks. It has been argued on computational grounds that to perform different tasks it must have access to multiple representations of space and the capacity to combine them (Andersen & Buneo,
2002; Andersen, Snyder, Li, & Stricanne,
1993; Bremmer, Pouget, & Hoffmann,
1998; Boussaoud & Bremmer,
1999; Buneo, Jarvis, Batista, & Andersen,
2002; Cohen & Andersen,
2002). It is generally agreed that a weighted combination of proprioceptive and visual information is used to make a goal directed point and to correct a trajectory online (e.g., Saunders & Knill,
2004; Sober & Sabes,
2003). Visual information is weighted more heavily than proprioceptive information to localize the target in space, most likely in a viewer centered framework (e.g., van Beers, Baraduc, & Wolpert,
2002). This visual information then undergoes a transformation to be used to guide the hand. There is evidence to suggest that this final representation may be hand centered rather than gaze/viewer centered (e.g., McIntyre, Strata, & Lacquaniti,
1998) and that these maps evolve over time (e.g., Ilg, Schumann, & Thier,
2004). These models emphasize the necessity to weight the different sources of sensory feedback used in this position estimate, and accordingly to calculate uncertainty for a given position. We suggest that conscious perception, the basis for verbal report, always favors a gaze-centered representation (not to be confused with merely retinotopic excitation). When a saccade is being prepared, receptive fields shift in anticipation of a shift in position of the direction of gaze (Duhamel, Colby, & Goldberg,
1992). These shifts cause changes in the apparent directions of stimuli flashed, and so they are seen erroneously, shortly before and early in saccades, when the eye has not yet made the anticipated movement.