DOES OCULOMOTOR READINESS MEDIATE COGNITIVE CONTROL OF VISUAL-ATTENTION - REVISITED

At Attention and Performance VIII, Klein proposed that endogenous covert orienting of attention might be accomplished by preparing to move the eyes to the to-be-attended location (Klein 1980). This ''oculomotor readiness hypothesis'' made two distinct predictions, each of which was tested in a dual-task situation. First, if the subject is attending to a location, eye movements to that location should be facilitated. Second, if the subject is preparing to move his or her eyes to a particular location, the detection of events presented there should be facilitated. Neither prediction was confirmed, and it was concluded that endogenous covert orienting if generated independently of the oculomotor system. The oculomotor readiness hypothesis has experienced something of a revival recently (cf. Rizzolatti et al. 1987; Shepard, Findlay, and Hockey 1986). This revival encouraged us to conduct two new tests of the predictions described above - tests not subject to alternative explanations that might apply to Klein's (1980) earlier experiments. The oculomotor readiness hypothesis was again disconfirmed. Our findings, together with the recent literature, suggest the following conclusions: (1) There is a tight linkage between attention and saccade execution; shifts of attention precede shifts in gaze; (2) attention is strongly activated by stimulus events that normally elicit eye movements even when they are suppressed; and (3) attention is not linked to endogenously generated saccadic programming when these programs are not executed.