Detection of noisy visual targets: Models for the effects of spatial uncertainty and signal-to-noise ratio

Brigham and Women’s Hospital, Boston, Massachusetts 02115 An “extreme-detector” model for detecting spatially uncertain targets in noisy backgrounds predicts how both detection and localization abilities are degraded by increasing the number of possible target locations. Experiments 1 and 2 show that the model accurately predicts detection and localization performance in tasks with two, four, and eight locations from d’ estimates of the observer’s ability to detect the target in a known spatial location. These predictions can be linked to the physical stimuli by combining the extreme-detector model with a “psychophysical” model that specifies how stimulus measures determine the target’s detectability in a given location. Single-parameter fits of four such combined models were compared with estimates of detection and localization performance in Experiment 3, which manipulated the target’s physical signal-to-noise ratio across various conditions of an eightlocation task.