D. Kersten - Academia.edu (original) (raw)

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Papers by D. Kersten

How do observers recognize faces despite dramatic image variations that arise from changes in ill... more How do observers recognize faces despite dramatic image variations that arise from changes in illumination? This paper examines 1) whether face recognition is sensitive to illumination direction, and 2) whether cast shadows improve performance by providing information about illumination, or hinder performance by introducing spurious edges. In Experiment 1, observers judged whether 2 sequentially-presented faces, illuminated from the same or different directions, were the same or different individuals. Cast shadows were present for half of the observers. Performance was impaired by a change in the illumination direction and by the presence of shadows. In Experiment 2, observers learned to name 8 faces under one illumination direction (left/right) and one cast-shadow condition (present/absent); they were later tested under novel illumination and shadow conditions. Performance declined for unfamiliar illumination directions, but not for unfamiliar shadow conditions. The finding that fa...

Advances in neural information …, 2004

Workshop on Statistical and …, 1999

PLoS Computational Biology, 2010

Pattern Recognition, 2011

Perception, 1997

Phenomenally strong visual illusions are described in which the motion of an object‘s cast shadow... more Phenomenally strong visual illusions are described in which the motion of an object‘s cast shadow determines the perceived 3-D trajectory of the object. Simply adjusting the motion of a shadow is sufficient to induce dramatically different apparent trajectories of the object casting the shadow. Psychophysical results obtained with the use of 3-D graphics are reported which show that: (i) the information provided by the motion of an object's shadow overrides other strong sources of information and perceptual biases, such as the assumption of constant object size and a general viewpoint; (ii) the natural constraint of shadow darkness plays a role in the interpretation of a moving image patch as a shadow, but under some conditions even unnatural light shadows can induce apparent motion in depth of an object; (iii) when shadow motion is caused by a moving light source, the visual system incorrectly interprets the shadow motion as consistent with a moving object, rather than a moving...

Philosophical Transactions of the Royal Society B: Biological Sciences, 1997

The central problems of vision are often divided into object identification and localization. Obj... more The central problems of vision are often divided into object identification and localization. Object identification, at least at fine levels of discrimination, may require the application of top–down knowledge to resolve ambiguous image information. Utilizing top–down knowledge, however, may require the initial rapid access of abstract object categories based on low–level image cues. Does object localization require a different set of operating principles than object identification or is category determination also part of the perception of depth and spatial layout? Three–dimensional graphics movies of objects and their cast shadows are used to argue that identifying perceptual categories is important for determining the relative depths of objects. Processes that can identify the causal class (e.g. the kind of material) that generates the image data can provide information to determine the spatial relationships between surfaces. Changes in the blurriness of an edge may be characteri...

Poster presented at the Annual Meeting of The Association for Research in Vision and Ophthalmology, Jun 2, 2006

Purpose: How do observers recognize objects despite dramatic image variations that arise from cha... more Purpose: How do observers recognize objects despite dramatic image variations that arise from changes in illumination? Some evidence suggests that changes in illumination direction influence object recognition (Kersten et al., ARVO 1995). We examine whether illumination dependency extends to face recognition. A corollary issue is whether cast shadows improve performance by providing information about light source direction, or hinder performance by introducing spurious edges that must be discounted prior to ...

The light reaching the eye confounds the proportion of light reflected from surfaces in the envir... more The light reaching the eye confounds the proportion of light reflected from surfaces in the environment with their illumination. To achieve constancy in perceived surface reflectance (lightness) across variations in illumination, the visual system must infer the relative contribution of reflectance to the incoming luminance signals. Previous studies have shown that contour and stereo cues to surface shape can affect the lightness of sawtooth luminance profiles. Here, we investigated whether cues to surface shape provided solely by motion (via the kinetic depth effect) can similarly influence lightness. Human observers judged the relative brightness of patches contained within abutting surfaces with identical luminance ramps. We found that the reported brightness differences were significantly lower when the kinetic depth effect supported the impression of curved surfaces, compared to similar conditions without the kinetic depth effect. This demonstrates the capacity of the visual sy...