Selective Search for the Target Properties Color and Form (Selectief Zoeken naar Kleur en Vorm)

Three search experiments tested whether the preattentive parallel stage of visual processing can selectively guide the attentive stage to a particular known-to-be-relevant-target feature. Subjects searched multi-element displays for a salient green circle which had a unique form when surrounded by green nontarget squares or had a unique color when surrounded by red nontarget circles. In the distractor conditions, a salient item in the other dimension was present as well. As an extension of earlier findings Theeuwes, 1991, the results showed that top-down selectivity towards a particular feature was not possible, not even after extended and consistent practice. The results reveal that selectivity depends on the relative discriminability of the form and color dimension. In an additional analysis the effect of the distance between target and distractor is examined.