Three main hypotheses exist concerning the most informative local features of contour for binding processes, allowing visual object identification: vertices and 3D features (Biederman, 1987 ; Boucart et al, 1995), midsegments elements (Kennedy R& Domander, 1985, Singh & Fulvio, 2005), and the interaction betweenfragmentation type and complexity of the global form (Panis & Wagemans, 2009). The aim of this work is to confront these hypotheses, while trying to determine the level (conscious or unconscious) at which the detection and the processing of these features occur. Conscious and unconscious priming paradigms are employed. Drawings of fragmented objects contain either vertices and 3D features or midsegment elements. They are used as primes, preceding a fragmented target image of the same object containing identical or complementary contour features. None of these four experiments highlight a qualitative effect of fragmentation types. However, a quantitative priming effect can be observed under certain timing conditions. Our results confirm the ambiguity emerging from literature concerning the most informative contour features and the necessity of a high degree of automatism of the processes involved in order to highlight perceptual priming effects
