Browsing CAS/CNS Technical Reports by Author "Pessoa, Luiz"

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Browsing CAS/CNS Technical Reports by Author "Pessoa, Luiz"

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  • Pessoa, Luiz; Mingolla, Ennio; Neumann, Heiko (Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems, 1994-05)
    A neural network model of brightness perception is developed to account for a wide variety of data, including the classical phenomenon of Mach bands, low- and high-contrast missing fundamental, luminance staircases, and ...
  • Pessoa, Luiz; Ross, William D. (Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems, 1995-08)
    Wallach's ratio hypothesis states that local luminance ratios clr!termine lightness perception under variable illumination. While local luminance ratios successfully discount gradual variations in illumination (illumination ...
  • Pessoa, Luiz (Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems, 1995-06)
    Mach bands are illusory bright and dark bands seen where a luminance plateau meets a ramp, as in half-shadows or penumbras. Ratliff, Milkman, and Kaufman (1983) showed that Mach bands are attenuated by placing stimuli, ...
  • Pessoa, Luiz (Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems, 1995-03)
    Mach bands are illusory bright and dark bands seen where a luminance plateau meets a ramp, as in half-shadows or penumbras. A tremendous amount of work has been devoted to studying the psychophysics and the potential ...
  • Mingolla, Ennio; Neumann, Heiko; Pessoa, Luiz (Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems, 1994-02)
    A neural network model of brightness perception is developed to account for a wide variety of difficult data, including the classical phenomenon of Mach bands and nonlinear contrast effects associated with sinusoidal ...
  • Pessoa, Luiz; Ross, William (Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems, 1995-05)
    A neural network model of 3-D lightness perception is presented which builds upon the FACADE Theory Boundary Contour System/Feature Contour System of Grossberg and colleagues. Early ratio encoding by retinal ganglion neurons ...
  • Pessoa, Luiz; Beck, Jacob; Mingolla, Ennio (Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems, 1995-03)
    An element-arrangement pattern is composed of two types of elements that differ in the ways in which they are arranged in different regions of the pattern. We report experiments on the perceived segregation of chromatic ...
  • Pessoa, Luiz; Mingolla, Ennio; Arend, Larry (Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems, 1995-08)
    Lightness constancy requires the visual system to somehow "parse" the input scene into illumination and reflectance components. Experiments on the perception of lightness for 3-D curved objects show that human observers ...
  • Neumann, Heiko; Pessoa, Luiz (Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems, 1994-02)
    A model is described for cortical simple cells. Simple cells are selective for local contrast polarity, signaling light-dark and dark-light transitions. The proposed new architecture exhibits both linear and non-linear ...
  • Grossberg, Stephen; Pessoa, Luiz (Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems, 1996-08)
    A widespread view is that most of texture segregation can be accounted for by differences in the spatial frequency content of texture regions. Evidence from both psychophysical and physiological studies indicate, however, ...

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