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Tessa C J Wit, Rob J Lier; Investigating visual completion: the visual search paradigm versus the change detection paradigm. Journal of Vision 2003;3(9):759. doi: 10.1167/3.9.759.
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© ARVO (1962-2015); The Authors (2016-present)
For some partly-occluded shapes various visual completions can be predicted. We tested the applicability of the visual search paradigm and the change detection paradigm to investigate the plausibility of different completions and also compared both methods. In the visual search task participants had to search for a completed shape (i.e., the target) amongst partly occluded shapes (i.e., the distractors). The change detection task was similar, only now the aforementioned display was alternated with a display containing only distractors; in this distractor display (500 ms) the completed shape was now a partly-occluded shape. Between these displays a white screen (120 ms) appeared. The targets were either a global or a local completed form of the partly occluded shape. From our earlier research we knew that the global completions were more plausible for the particular shapes we used (De Wit & Van Lier, 2002). It takes less time for participants to detect targets in the visual search task than in the change detection paradigm. For both the visual search paradigm and the change detection paradigm, the time it took participants to detect the target was longer for global completions than for local completions, indicating that global completions were less striking and therefore more plausible completions. However, the difference in search time between global and local targets is significantly greater in the change detection paradigm. Both paradigms are suited to investigate the plausibility of different completions, but the change detection paradigm seems to be the most sensitive tool of the two. Results will be discussed in the light of processing differences between the paradigms.
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