ORCID Profile
0000-0003-1486-9834
Current Organisation
UNSW Sydney
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Publisher: Elsevier BV
Date: 11-2023
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 26-10-2023
DOI: 10.1167/JOV.23.12.9
Publisher: Center for Open Science
Date: 15-11-2022
Abstract: To recover the reflectance and shape of an object in a scene, the human visual system must account for the properties of the light (such as the direction) illuminating the object. Here, we examine the extent to which multiple objects within a scene are utilised to estimate the direction of lighting in a scene. In Experiment 1, we presented participants with rendered scenes that contained 1, 9, or 25 unfamiliar blob-like objects and measured their capacity to discriminate whether a directional light source was left or right of the participants' vantage point. Trends reported for ensemble perception suggest that the number of utilised objects---and, consequently, discrimination sensitivity---would increase with set size. However, we find little indication that increasing the number of objects in a scene increased discrimination sensitivity. In Experiment 2, an equivalent noise analysis was used to measure participants' internal noise and the number of objects used to judge the average light source direction in a scene, finding that participants relied on 1 or 2 objects to make their judgement regardless of whether 9 or 25 objects were present. In Experiment 3, participants completed a shape identification task that required an implicit judgement of light source direction, rather than an explicit judgement as in Experiment 1 and 2. We find that sensitivity for identifying surface shape was comparable for scenes containing 1, 9, and 25 objects. Our results suggest that the visual system relied on a small number of objects to estimate the direction of lighting in our rendered scenes.
Publisher: Springer Science and Business Media LLC
Date: 08-2023
DOI: 10.3758/S13414-023-02718-0
Abstract: To recover the reflectance and shape of an object in a scene, the human visual system must account for the properties of the light illuminating the object. Here, we examine the extent to which multiple objects within a scene are utilised to estimate the direction of lighting in a scene. In Experiment 1, we presented participants with rendered scenes that contained 1, 9, or 25 unfamiliar blob-like objects and measured their capacity to discriminate whether a directional light source was left or right of the participants’ vantage point. Trends reported for ensemble perception suggest that the number of utilised objects—and, consequently, discrimination sensitivity—would increase with set size. However, we find little indication that increasing the number of objects in a scene increased discrimination sensitivity. In Experiment 2, an equivalent noise analysis was used to measure participants’ internal noise and the number of objects used to judge the average light source direction in a scene, finding that participants relied on 1 or 2 objects to make their judgement regardless of whether 9 or 25 objects were present. In Experiment 3, participants completed a shape identification task that required an implicit judgement of light source direction, rather than an explicit judgement as in Experiments 1 and 2. We find that sensitivity for identifying surface shape was comparable for scenes containing 1, 9, and 25 objects. Our results suggest that the visual system relied on a small number of objects to estimate the direction of lighting in our rendered scenes.
Publisher: American Psychological Association (APA)
Date: 12-2018
DOI: 10.1037/XHP0000575
Abstract: 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 r s. 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 system to use shape from motion to "explain away" alternative interpretations of luminance gradients, and supports the cue-invariance of the interaction between shape and lightness. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
No related grants have been discovered for Lindsay Peterson.