THE RELATIONSHIP BETWEEN CENTRAL CUES AND PERIPHERAL CUES IN COVERT VISUAL ORIENTATION

Four experiments were conducted to compare valid and invalid cue condi tions for peripheral and central cues. Experiments 1, 3, and 4 used re action time (RT) as the dependent variable. Experiment 2 used a thresh old measure. Peripheral and central cues were presented on each trial. The peripheral cue was uninformative in all experiments. The central cue was informative in Experiments 1 and 2, where it predicted stimulu s side on 70% of the trials. Experiment 3 included 50% and 100% centra l-cue prediction conditions as well as the 70% treatment. Experiment 4 included 60%, 75%, and 90% central-cue prediction conditions. The eff ects of the central and peripheral cues were independent and additive in all four experiments, indicating that: (1) both cue types can act s imultaneously and that the relationship between them is additive under the conditions used in these experiments, (2) informativeness is not a necessary condition for attentional effects with peripheral cues, an d (3) covert visual orientation influences sensory thresholds and RT i n similar ways. The results of Experiments 3 and 4 demonstrated that t he facilitation associated with peripheral cues was insensitive to man ipulations which demonstrate that subjects use the informational value of the central cue to direct voluntary attention. The results are dis cussed with reference to two issues; first, the proposition that centr al and peripheral cues exert their influence on performance in indepen dent information-processing stages, following the additive factor meth od, and, second, the problems raised for additive factors method when cues elicit both an ''explicit'' response-regarding the presence or ab sence of a specified letter-and an ''implicit response''-involving the planning and possible execution of eye and hand movements.