Visual information transfer across eye movements in the monkey

During normal viewing, the eyes move from one location to another in order to sample the visual environment. Information acquired before the eye movement facilitates post-saccadic processing. This "preview effect" indicates that some information is maintained in transsaccadic memory and combined with information acquired at the next fixation. However, the nature of transsaccadic memory remains a subject of debate. Here, we investigate preview effects in monkeys that carry out a contour-grouping (curve-tracing) task, by manipulating the consistency between pre- and post-saccadic information. The results show that consistent information causes a preview benefit, whereas inconsistent information causes a preview cost. These preview effects are relatively independent of the pre-saccadic viewing duration, and they occur even when the stimulus is exposed for only approximately 10 ms. The results further demonstrate that an entire relevant curve is stored in transsaccadic memory, instead of just the items at the saccade goal. They suggest that preview effects are caused by a mechanism that stores attended sensory information to make it available at the next fixation. The results are discussed within a theoretical framework that establishes an intimate relationship between attention, short-term memory and transsaccadic memory.