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Natural extinction: A criterion shift phenomenon

Presents 3 experiments where identical targets are displayed (1) at the same eccentricity but in opposite hemifields, (2) at different eccentricities, and (3) where different spatial frequency targets of equal contrasts are displayed at the same eccentricity. Hemifield, eccentricity, and spatial frequency manipulations were intended to entail sensitivity differences for identical contrast stimuli. Some observers showed up to 3 and 1.5 d'-units differences between their left and right and between their upper and lower hemifields, respectively. Although observers (N = 5; aged 18-22 yrs and 48 yrs) may show response biases even for isolated stimuli as well as for equally visible ones presented together, it is always the case that they use higher response criteria for the less visible targets and lower response criteria for the more visible ones when these stimuli are mixed in 1 experimental block. The observed criterion shifts translate into as much as 3 times more "'Not seen" responses for the less visible targets and into about 1.3 times more "'Seen" responses for the more visible ones. Data support the notion that some forms of extinction are contingent on relative sensory/perceptual impairments and that they reflect more or less drastic forms of criterion/decision shifts. (PsycINFO Database Record (c) 2005 APA, all rights reserved)



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