ORIENTATION ASYMMETRY IN THE FLANKER TASK

Experiments 1 and 2 of this study show that when the target is either a vertical or a horizontal line, diagonal-line flankers tilted 45-degr ees either to the right or to the left have the same effect as do inco ngruent flankers. When the target is a diagonal line tilted either to the right or to the left, vertical- or horizontal-line flankers do not have the same effect as do incongruent flankers. Experiment 3 demonst rates that this asymmetry is not caused by the temporal-dynamic aspect s of the processing. Together, these experiments suggest that there is an asymmetrical relation between diagonal lines and either vertical o r horizontal lines outside of the central focus of attention. Experime nt 4 shows that despite this asymmetry in the flanker task, visual sea rch for a vertical- or a horizontal-line target among diagonal-line di stractors is not affected by the number of distractors. Possible expla nations of this phenomenon are discussed.