is shininess a basic feature in visual search? f111 · is shininess a basic feature in visual...
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Is Shininess A Basic Feature In Visual Search?Randall S. Birnkrant Jeremy M. Wolfe Melina A. Kunar Matthew Sng
Brigham & Women's Hospital Brigham & Women's Hospital & Harvard Medical School Research Science Institute studentA limited set of attributes (e.g. color, size, and a varietyof depth cues) can guide the deployment of attention invisual search. Do monocular cues to shininess serveas guiding attributes?
INTRODUCTION
Rensink & Cavanagh (1994) found rapid search for acylinder with a top highlight, suggesting information aboutspecular reflectance is available at early levels of vision.
CONCLUSIONS
General MethodObservers (Os) were told to respond quickly and accurately. They were alsoinstructed to minimize eye movements. Stimuli remained on-screen until aresponse was made. Targets were present in approximately 50% of trials.Searches were blocked by target.
Does shininess guide attention? Static Stimuli
Experiment 2
Experiment 3
Experiment 5
Subjective ratings ofshininess by aseparate group ofparticipants (n=11).
Experiment 4
Stimuli:Shiny spheres rendered using photographicallycaptured real-world illuminations were takenfrom the work of Fleming, Dror, & Adelson(2003). Matte spheres were created by carvingup the specular reflections and replotting them.Clearly, the latter distorts global shapeinformation. However, this is only a potentialconfound if these searches proved to beefficient.
Results:Both searches provedinefficient. Shiny target #1did produce a noticeablyshallow search slope (7ms/item, shininess rating:8) and deserves furtherinvestigation.
Stimuli:Os searched for targets defined byconjunctions of shape (spherical orrectangular) and shininess. Thus, a searchtarget could either be a plain sphere, a shinysphere, or a rectangle cropped from thesame spherical specular reflection. Ifshininess is a feature, shininess-shapeconjunctions should yield efficient searches.
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Results: SEARCH FOR THE CONJUNCTIONOF SHININESS AND SHAPE WAS NOTEFFICIENT. Its not that these stimuli are toocomplex or noisy to support efficient search.Shiny rectangles among shiny and mattespheres popped out, as did matte spheresamong two types of shiny objects. However,observers could not use the combination ofshininess and shape to guide attention.
Stimuli:Similar to Experiment 1, shiny and matte sphereswere distinguished by either a white highlight ordark patch. The spheres were now textured(rotating uniform spheres are pretty dull) and oscil-lated through an angle of ~ 70 deg at 3 Hz. Again,disks containing the opposite dot polarity wereplaced just above the spheres to thwart searchstrategies dependent on locating a particular dotpolarity in the display. Control conditions were runin which Os searched for a specific configuration oflight and dark patches on a flat surface.
Results:Although target present RT x Set size slopes werequite shallow, SEARCHES WERE NOT FEATURE-LIKE. Again, it does not appear that Os weresearching for a particular configuration of light anddark patches.
Stimuli:Hartung & Kersten (2002) created compelling shiny andmatte “kettles” where surface appearance was defined bythe motion of specular reflections. Shiny kettles haddynamic specular reflections, whereas matte kettles hada “sticky” reflection - a single instance of specular reflec-tion that rotated with the kettle. Stimuli oscillated throughan angle of ~ 30 deg at 0.6 Hz. Rotational phase was ran-domly chosen for each stimulus to avoid grouping effects.The kettles did oscillate about different axes, but this isonly a potential confound if the searches proved to be effi-cient.
1. Although monocular information regarding specularreflectance may be available at early levels of vision, arange of compelling shiny and matte stimuli fail toproduce efficient search. Therefore, presentinformation suggests that shininess does not act as abasic feature.
2. Perhaps the necessary range of perceptual distancebetween stimuli wasn’t achieved with our stimuli (inspite of the fact that we used a variety of stimulustypes). We remain on the lookout for better distractorsets that continue to control for confounding factors(e.g., motion, spatial frequency, color).
3. While generalized “shininess” does not seem toguide attention, it may be that more specific stimulusconfigurations like binocular luster can support efficientsearch.
References
Comments
This project was funded by a grant from NEI
Background: Wolfe & Franzel (1988) reported efficientsearch performance for stimuli defined by binocular luster...
Monocular cues produce robust shininess percepts, evenwhen contextual information is removed or replaced(Fleming, Dror, & Adelson, 2003; Hartung & Kersten, 2002).
Back to the monocular world...
from Fleming, R. W., Dror, R. O. and E. H. Adelson (2003)
Does shininess guide attention? Moving Stimuli
Our thanks to Roland Fleming, Ron Dror, Ted Adelson, Bruce Hartung, andDan Kersten for allowing us to use their stimuli.
Fleming, R. W., Dror, R. O. and E. H. Adelson (2003). Real world illumination and the perception of surface reflectance properties.Journal of Vision 3(5), 347-368.
Hartung, B., and Kersten, D. (2002). Distinguishing shiny from matte [Abstract]. Journal of Vision, 2(7), 551a,http://www.journalofvision.org/2/7/551/, DOI 10.1167/2.7.551.
Rensink, R.A. and Cavanagh P. (1994). Identification of Highlights in Early Vision. Investigative Ophthalmology & VisualScience,35:1623. [ARVO 1994; Sarasota, FL.]
Wolfe, J. M. and Franzel, S. L. (1988). Binocularity and Visual Search. Perception & Psychophysics 44, 81-93.
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Stimuli:Spheres (4.5 dva) with either a white highlight(shiny) or dark patch (matte) were used. Disks(1 dva) containing the opposite dot polarity wereplaced just above the spheres to thwart searchstrategies dependent on locating a specific dotpolarity in the display. A control condition wasrun in which observers searched for a specificconfiguration of light and dark patches on a flatsurface.
Experiment 1TARGET PRESENT TRIALS
Results:All searches were inefficient. It does notappear Os were searching for a particularconfiguration of light and dark patches.
TARGET PRESENT TRIALS TARGET ABSENT TRIALS
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Os searched for the presence of a member of their target set.
Subjective ratingsof shininess by aseparate group ofparticipants (n=11).
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by fusing these images, observers would perceive a salient lustrous patch where indicated in red.
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matte vs. shinyy = 44x + 515
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Subjective ratings ofshininess by aseparate group ofparticipants (n = 11).
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shiny vs. mattey = 22x + 451
matte vs. shinyy = 38x + 427
dot configurationy = 79x + 432
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y= 67x + 484shiny vs. matte
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plain spherey = 6x + 389
rect angley = -x + 455
shiny spherey = 27x + 492
plain spherey = -2x + 501
rect angley = 4x + 476
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dot configuration 1y = 45x + 628
dot configuration 2y = 42x + 647
matte vs. shinyy = 10x + 573
shiny vs. mattey = 18x + 553
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dot configuration 1y = 94x + 606
dot configuration 2y = 107x + 567
shiny vs. mattey = 41x + 609
matte vs. shinyy = 28x + 612
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shiny vs. mattey = 41x + 808
matte vs. shinyy = 26x + 790
Results:Both searches were inefficient.
shiny vs. mattey = 107x + 867
matte vs. shinyy = 94x + 881
TARGET ABSENT TRIALS
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green = the crit ical condit ion
Vision Sciences Society2004
a sample search display(2/3rds original size)
a sample search display(1/2 original size)
shiny sphere
rectangle
plain sphere
search for: among:
a sample search display
a sample search display(1/2 original size)
search for: among:
control
search for: among:
a sample search display
a sample search display(1/2 original size)
search for: among:
a sample search display(1/2 original size)
search for: among:
control