Uncertainty explains many aspects of visual contrast detection and discrimination

Abstract

More than 20 years ago, Tanner [Ann. N.Y. Acad. Sci. 89, 752 (1961)] noted that observers asked to detect a signal act as though they are uncertain about the physical characteristics of the signal to be detected. The popular assumptions of probability summation and decision variable, taken together, imply this uncertainty. This paper defines and uncertainty model of visual detection that assumes that the observer is uncertain among many signals and chooses the likeliest. With only four parameters, the uncertainty model explains why d' is approximately a power function of contrast ("nonlinear transduction") and accurately predicts effects of summation, facilitation, noise, subjective criterion, and task for near-threshold contrast. Thus the uncertainty model offers a synthesis of much of our current understanding of visual contrast detection and discrimination.

Auditory discrimination in female adolescents varying in schizotypal features: Preliminary findings

“…This result suggests that the impairment in auditory discrimination in subjects with schizotypal traits could involve a mechanism different from that implicated in schizophrenia -a mechanism that may not be directly related to perceptual attention, at least not as have been conceived by the theories of perceptual signal detection. 23,24 A recent study shows that the anxiety component of schizotypy, more than the perceptual disorganization component, accounts for the attentional dysfunction in high schizotypals, as measured by the magnitude of disruption in a latent inhibition task. 45 Although mostly speculative at this point, we are also tempted to propose that the impairment in auditory discrimination observed for the subjects with high SPQ (and PAS, as well as CHQ) score in the current study may to a certain extent be attributed to a non-psychotic factor such as anxiety.…”

“…12 While these studies explore attention and auditory information processing as independent functional modules, a psychophysical model based on theories of signal detection provides a unified perspective where the two functions can be examined together. 23,24 Indeed, a more recent study shows that patients with schizophrenia have shallower psychometric functions in auditory detection and discrimination, which in turn can result from a deficit in auditory attention. 25 Following up on this earlier experiment, the present study investigates whether adolescents varying in schizotypal features differ in their performance in auditory discrimination.…”

On the relation between summation and facilitation

“…determines the log-log steepness; and y is the "guessing" rate W(0) = y. For 2afc experiments y is 0.5, so the threshold criterion P(a) is 0.816. where c,-,,~ is the contrast at which d' is 1 (and the proportion correct is 0.76), and b is the log-log steepness (Nachmias and Sansbury, 1974;Foley and Legge, 1981;Pelli, 1985), d' is defined by…”

“…A quantitative relationship between summation and facilitation has already been deduced for a particular model of visual detection by Pelli (1985). There it was argued that the popular assumptions of probability summation and that the observer uses a decision variable together imply that the observer acts as though uncertain of the physical parameters of the signal.…”

Verification of DICOM GSDF in Complex Backgrounds

“…Testing by Barten and others [7][8][9][10] used a sinusoidal grating pattern on a uniform background to cover the luminance range of the visual system. While a uniform background is necessary for model development, it does not represent clinical images.…”