9615988 IRWIN People make rapid eye movements called saccades in order to examine the world around them. The still periods between saccades are called fixations. It is well known that vision is suppressed during saccades; therefore, visual information about the world is acquired only during fixations. This research will investigate whether saccades also interfere with particular cognitive processes. Preliminary findings suggest that this may be true, but the evidence is not convincing; this research will provide some steps toward a definitive answer. The experiments will examine whether cognitive processes that are set into motion during one eye fixation continue to operate while the eyes are moving to a new position in space or whether these processes pause during the eye movement. People will be presented with a simple mental task that they will begin to perform while they are fixating one position in space and will then make either a short or a long saccade to a different position in space while attempting to continue performing the task. If cognitive processing is suppressed during eye movements, then long saccades (which take longer to execute) should disrupt performance more than short saccades (which take less time to execute). Performance will also be measured in another condition, in which the eyes do not move. Performance in the eye-movement conditions should be equivalent to performance in the no-eye-movement condition if eye movements do not interfere with cognition. The average person makes about three saccades per second (hence, about 172,800 saccades per 16-hour working day), and the average saccade lasts about 30 ms; thus, if suppression occurs during saccades, it would mean that cognition is disrupted for approximately ninety minutes each day. If this happens, it is truly remarkable. Thus, determining whether this occurs is of fundamental importance to the understanding of human cognition, particularly for activities such as reading and scene perception that require many eye movements. ***
