Attention during pauses between successive saccades: Task interference vs. modulation of contrast-gain

Perceptual performance is better at the target of a saccade than other locations (Gersch et al., 2009). To better understand pre-saccadic attention shifts, four experiments were carried out that measured perceptual discrimination and detection across different stimulus contrasts during pauses between successive saccades.;In Experiment 1, displays contained 4 squares located at the corners of an imaginary square. Subjects made saccades along a V-shaped path from one corner to another. Oriented T's appeared in each square when the eye reached the center. The orientation of a randomly-selected T was reported after scanning was completed. Orientation discrimination was poor at non-saccadic-goal locations, even at the highest contrast. These performance losses could be due to selective decay of visual memory (Gersch et. al., 2008).;Experiment 2 presented a single oriented Gabor in either the saccadic goal or the opposite location to decrease the memory load. Perceptual reports were required at different rate. A small perceptual enhancement at the saccadic goal location was observed regardless the external noise levels or the report rate. Saccadic pause durations were prolonged when the Gabor was detected at the opposite location, reflecting an attempt to improve perceptual discrimination by delaying the saccade.;Experiment 3 presented two Gabors simultaneously, prevented subjects from knowing the report location and adjusting strategy. Saccadic pause durations were prolonged when report frequently, showing that emphasizing a perceptual task could affect saccadic performance even without location cue. Perceptual enhancement was larger when report infrequently. Experiment 4 shows that the perceptual enhancement still existed with a detection task, which reduced the memory load.;These results show that fixation pause durations were increased by attention to a non-saccadic-goal location, and that perceptual performance was better at the saccadic goal location, supporting that perception and saccades use a common attentional filter. In contrast to attention shifts controlled by cues during maintained fixation, the pre-saccadic attention shifts were found both with and without the external noise, across the whole range of the stimuli contrasts, and regardless of memory load. This shows that multiple mechanisms of visual attention must be involved in pre-saccadic attention shifts.