The VideoToolbox software for visual psychophysics: transforming numbers into movies.
- D. Pelli
- Computer ScienceSpatial Vision
The VideoToolbox is a free collection of two hundred C subroutines for Macintosh computers that calibrates and controls the computer-display interface to create accurately specified visual stimuli.…
What's new in Psychtoolbox-3?
Quest: A Bayesian adaptive psychometric method
An adaptive psychometric procedure that places each trial at the current most probable Bayesian estimate of threshold is described. The procedure takes advantage of the common finding that the human…
Crowding is unlike ordinary masking: distinguishing feature integration from detection.
The results suggest that ordinary masking blocks feature detection, so the signal disappears, while crowding (like "illusory conjunction") is excessive feature integration - detected features are integrated over an inappropriately large area because there are no smaller integration fields - so the integrated signal is ambiguous, jumbled with the mask.
Uncertainty explains many aspects of visual contrast detection and discrimination.
- D. Pelli
- PhysicsJournal of the Optical Society of America. A…
- 1 September 1985
The uncertainty model offers a synthesis of much of the current understanding of visual contrast detection and discrimination and accurately predicts effects of summation, facilitation, noise, subjective criterion, and task for near-threshold contrast.
The uncrowded window of object recognition
The explosion of studies on crowding is reviewed—in grating discrimination, letter and face recognition, visual search, selective attention, and reading—and a universal principle, the Bouma law is found, which is equal for all objects, although the effect is weaker between dissimilar objects.
THE DESIGN OF A NEW LETTER CHART FOR MEASURING CONTRAST SENSITIVITY
It is concluded that, for a clinical test, letters are more suitable than gratings, and a mathematical model of the observer and the chart-testing procedure has been used to predict how the accuracy and repeatability of the test score depend on the parameters of the chart and observer.
Feature detection and letter identification
Pixel independence: measuring spatial interactions on a CRT display.
- D. Pelli
- PhysicsSpatial Vision
Two tests are recommended for assessing a CRT's deviation from the pixel-independence model, because most monitors have inadequate video bandwidth, DC restoration, and high-voltage regulation to live up to this ideal model.