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Barbara Nordhjem, Constanza I. Kurman Petrozzelli, Nicolás Gravel, Remco J. Renken, Frans W. Cornelissen; Eyes on emergence: Fast detection yet slow recognition of emerging images. Journal of Vision 2015;15(9):8. doi: 10.1167/15.9.8.
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© ARVO (1962-2015); The Authors (2016-present)
Visual object recognition occurs at the intersection of visual perception and visual cognition. It typically occurs very fast and it has therefore been difficult to disentangle its constituent processes. Recognition time can be extended when using images with emergent properties, suggesting they may help examining how visual recognition unfolds over time. Until now, their use has been constrained by limited availability. We used a set of stimuli with emergent properties—akin to the famous Gestalt image of a Dalmatian—in combination with eye tracking to examine the processes underlying object recognition. To test whether cognitive processes influenced eye movement behavior during recognition, an unprimed and three primed groups were included. Recognition times were relatively long (median ∼ 5s for the unprimed group), confirming the object's emergent properties. Surprisingly, within the first 500 ms, the majority of fixations were already aimed at the object. Computational models of saliency could not explain these initial fixations. This suggests that observers relied on image statistics not captured by saliency models. For the primed groups, recognition times were reduced. However, threshold-free cluster enhancement-based analysis of the time courses indicated that viewing behavior did not differ between the groups, neither during the initial viewing nor around the moment of recognition. This implies that eye movements are mainly driven by perceptual processes and not affected by cognition. It further suggests that priming mainly boosts the observer's confidence in the decision reached. We conclude that emerging images can be a useful tool to dissociate the perceptual and cognitive contributions to visual object recognition.
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