Abstract

To investigate the processing of triangle and arrow under tachistoscopic condition, detection rates of post-cued targets were compared between the repetitive condition that the two simultaneously presented forms were the same and the alternative condition that they were different. Triangle and arrow were made by adding left or right diagonal to the context of L- shaped angle. With the two diagonal lines as possible targets positive repetition effect (that is, higher detection rate in the repetitive condition) was observed. On the contrary, with triangle and arrow as target candidates negative repetition effect (that is, higher detection rate in the alternative condition) was observed. Subsequent experiments were to study how the above repetition effects varied by using global (to form) or local (to diagonal or angle) attention task, making either diagonal or angle thick, or setting them disconnected. The results of five experiments showed that emergent features like closure and vertex were processed out of the briefly presented triangles and arrows, and the processing was affected by selective attention, other elementary features, and form compositions. Emergent features and angles were likely to be processed better than diagonals.