What limits simultaneous discrimination accuracy?
Discrimination accuracy decreases when viewers simultaneously monitor two perceptually distinct stimulus components for changes in a common property, e.g. contrast [Magnussen & Greenlee (1997). Journal of Experimental Psychology: Human Perception and Performance, 23, 1603-1616; Olzak & Wickens (1997). Perception, 26, 1101-1120]. We ask whether the limitation is in monitoring two components or in making dual decisions about a single property. Using the same uncertainty paradigm as Magnussen and Greenlee, we find no evidence of a processing limitation when viewers simultaneously monitor one component (1.25 c/d) for a possible change in contrast and a second component (5 c/d) for a possible change in spatial frequency, regardless of whether the components are spatially separated or superimposed. The limitation is in making dual decisions about a single property.
Thomas
J P
JP
Psychology Department, UCLA, Box 951563, CA 90095-1563, Los Angeles, USA. thomas@psych.ucla.edu
Magnussen
S
S
Greenlee
M W
MW
D001288:Attention / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology; D003657:Decision Making / Q000502:physiology*; D006801:Humans; D013028:Space Perception; D014796:Visual Perception / Q000502:physiology*