Alan Gilchrist
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780195187168
- eISBN:
- 9780199786725
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195187168.003.0010
- Subject:
- Psychology, Clinical Psychology
This chapter argues that the overall pattern of errors in human lightness perception offers a powerful method for identifying the kind of software used by the lightness system. In a systematic survey ...
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This chapter argues that the overall pattern of errors in human lightness perception offers a powerful method for identifying the kind of software used by the lightness system. In a systematic survey of lightness errors, it is demonstrated that many of the errors predicted by lightness theories do not occur, and many of the errors that do occur are not predicted by the theories. The computational models fail to account for errors, and error-driven models are proposed here.Less
This chapter argues that the overall pattern of errors in human lightness perception offers a powerful method for identifying the kind of software used by the lightness system. In a systematic survey of lightness errors, it is demonstrated that many of the errors predicted by lightness theories do not occur, and many of the errors that do occur are not predicted by the theories. The computational models fail to account for errors, and error-driven models are proposed here.
Alan Gilchrist
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780195187168
- eISBN:
- 9780199786725
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195187168.003.0012
- Subject:
- Psychology, Clinical Psychology
This chapter outlines and critiques all the main theories of lightness, laying out the strengths and weaknesses of each. These include the past experience theories, contrast theories, brightness ...
More
This chapter outlines and critiques all the main theories of lightness, laying out the strengths and weaknesses of each. These include the past experience theories, contrast theories, brightness models, decomposition models, and anchoring theory.Less
This chapter outlines and critiques all the main theories of lightness, laying out the strengths and weaknesses of each. These include the past experience theories, contrast theories, brightness models, decomposition models, and anchoring theory.
Alan Gilchrist
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780195187168
- eISBN:
- 9780199786725
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195187168.003.0011
- Subject:
- Psychology, Clinical Psychology
This chapter offers a specific error-driven theory of lightness framed in terms of the rules of anchoring. The lightness model described in Gilchrist et al. (1999) is presented in more detail in this ...
More
This chapter offers a specific error-driven theory of lightness framed in terms of the rules of anchoring. The lightness model described in Gilchrist et al. (1999) is presented in more detail in this chapter. Its principal strength is the wide range of lightness errors it can accommodate. Central to the model is its construction of the relationship between simple and complex images. The discussion starts with a consideration of lightness in simple images. At the heart of the anchoring model lies a critical assumption about the relationship between simple and complex images: the rules of anchoring found in simple images are applicable to frames of reference embedded within complex images. The same anchoring rules are held to apply to both.Less
This chapter offers a specific error-driven theory of lightness framed in terms of the rules of anchoring. The lightness model described in Gilchrist et al. (1999) is presented in more detail in this chapter. Its principal strength is the wide range of lightness errors it can accommodate. Central to the model is its construction of the relationship between simple and complex images. The discussion starts with a consideration of lightness in simple images. At the heart of the anchoring model lies a critical assumption about the relationship between simple and complex images: the rules of anchoring found in simple images are applicable to frames of reference embedded within complex images. The same anchoring rules are held to apply to both.
Alan Gilchrist
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780195187168
- eISBN:
- 9780199786725
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195187168.001.0001
- Subject:
- Psychology, Clinical Psychology
How the human visual system determines the lightness of a surface, that is, its whiteness, blackness, or grayness, remains, like vision in general, a mystery. In fact, we have not been able to create ...
More
How the human visual system determines the lightness of a surface, that is, its whiteness, blackness, or grayness, remains, like vision in general, a mystery. In fact, we have not been able to create a machine that can determine, through an artificial vision system, whether an object is white, black, or gray. Although the photoreceptors in the eye are driven by light, the light reflected by a surface does not reveal its shade of gray. Depending upon the level of illumination, a surface of any shade of gray can reflect any amount of light. This book ties together over thirty years of the author's own research on lightness, and presents an historical review of empirical work on lightness, covering the past 150 years of research on images ranging from the simple to the complex. The book also describes and analyzes the many theories of lightness — including the author's own — showing what each can and cannot explain. The book highlights the forgotten work conducted in the first third of the 20th century, describing several crucial experiments and examining the nearly unknown work of the Hungarian gestalt theorist, Lajos Kardos. The book's review also includes a survey of the pattern of lightness errors made by humans, many of which result in delightful illusions. It argues that because these errors are not random, but systematic, they are the signature of our visual software, and so provide a powerful tool that can reveal how lightness is computed. Based on this argument and the concepts of anchoring, grouping, and frames of reference, the book presents a new theoretical framework that explains an unprecedented array of lightness errors.Less
How the human visual system determines the lightness of a surface, that is, its whiteness, blackness, or grayness, remains, like vision in general, a mystery. In fact, we have not been able to create a machine that can determine, through an artificial vision system, whether an object is white, black, or gray. Although the photoreceptors in the eye are driven by light, the light reflected by a surface does not reveal its shade of gray. Depending upon the level of illumination, a surface of any shade of gray can reflect any amount of light. This book ties together over thirty years of the author's own research on lightness, and presents an historical review of empirical work on lightness, covering the past 150 years of research on images ranging from the simple to the complex. The book also describes and analyzes the many theories of lightness — including the author's own — showing what each can and cannot explain. The book highlights the forgotten work conducted in the first third of the 20th century, describing several crucial experiments and examining the nearly unknown work of the Hungarian gestalt theorist, Lajos Kardos. The book's review also includes a survey of the pattern of lightness errors made by humans, many of which result in delightful illusions. It argues that because these errors are not random, but systematic, they are the signature of our visual software, and so provide a powerful tool that can reveal how lightness is computed. Based on this argument and the concepts of anchoring, grouping, and frames of reference, the book presents a new theoretical framework that explains an unprecedented array of lightness errors.
Alan Gilchrist
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780195187168
- eISBN:
- 9780199786725
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195187168.003.0013
- Subject:
- Psychology, Clinical Psychology
This chapter draws conclusions from the current evidence regarding lightness perception. It is argued that the twin assumptions of raw sensations and their cognitive interpretation have undermined ...
More
This chapter draws conclusions from the current evidence regarding lightness perception. It is argued that the twin assumptions of raw sensations and their cognitive interpretation have undermined progress and should be discarded. Three sources of motivation for theories of lightness are described: physiology, veridicality, and error. The strengths and weaknesses of each are analyzed, and the current challenges for lightness theory are addressed.Less
This chapter draws conclusions from the current evidence regarding lightness perception. It is argued that the twin assumptions of raw sensations and their cognitive interpretation have undermined progress and should be discarded. Three sources of motivation for theories of lightness are described: physiology, veridicality, and error. The strengths and weaknesses of each are analyzed, and the current challenges for lightness theory are addressed.
Robert Schwartz
- Published in print:
- 2003
- Published Online:
- March 2012
- ISBN:
- 9780198505006
- eISBN:
- 9780191686764
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198505006.003.0015
- Subject:
- Psychology, Vision
This chapter explores the structure and complexity of claims about error in the perception of achromatic colours, that is, the perception of white, black, and the greys. These colours are said to ...
More
This chapter explores the structure and complexity of claims about error in the perception of achromatic colours, that is, the perception of white, black, and the greys. These colours are said to lack hue; they constitute what is known as the ‘grey-scale’. The most straightforward notion of ‘error’ found in lightness constancy studies is specified with respect to reflectance. This lightness error is defined as any difference between the physical reflectance of the target surface and the physical reflectance of the perceptually matching surface.Less
This chapter explores the structure and complexity of claims about error in the perception of achromatic colours, that is, the perception of white, black, and the greys. These colours are said to lack hue; they constitute what is known as the ‘grey-scale’. The most straightforward notion of ‘error’ found in lightness constancy studies is specified with respect to reflectance. This lightness error is defined as any difference between the physical reflectance of the target surface and the physical reflectance of the perceptually matching surface.
