Unconscious and conscious priming by forms and their parts

Using metacontrast masking techniques, in two experiments we compare unconscious and conscious response priming by targets consisting of either whole forms or else their parts. In Experiment I we investigate the contribution of whole forms and their figural primitives, viz., edges and corners, to the unconscious priming effect. As expected, choice RTs were fast when the invisible target and visible mask shape pairings were congruent and slower when they were incongruent. This trend, while strongest for whole-targets, also held for the target primes composed only of corners but did not hold for target primes composed only of sides. Experiment 2 showed, replicating the results of Experiment 1, that while invisible corner targets produced weaker priming effects than invisible whole targets, paradoxically visible corner target produced stronger priming effects than visible whole targets. Taken together the results of the two experiments indicate (a) that unconscious target representations and, thus, unconscious priming effects are strongest when the target is a complete rather than a partial configuration, (b) that conjunctions of line or edge orientations forming corners produce stronger unconscious target representations and priming effects than do unconscious target representations formed from nonconjoined edge or line primitives, (c) that metacontrast masking of form occurs at or beyond levels of visual processing at which feature integration of visual form primitives occurs, and (d) that, when consciously perceived, partial forms can act as stronger primes than whole forms.