Attention switching in depth using random-dot autostereograms: Attention gradient asymmetries

Random-dot autostereograms (RDASs) were used to investigate attention shift s along the sagittal plane in distractor;free tasks of high perceptual load . In three experiments using a same/different comparison task, the shape of the gradient over five different depths was examined and the conditions un der which the gradient is and is not observed were compared. When the targe t set consisted of five similar objects, a robust asymmetric depth gradient was observed. When the target set consisted of two dissimilar objects, no gradient was observed. The results support a hypothesis of a viewer-centere d asymmetric attention gradient in the depth plane that is dependent on per ceptual or attentional load defined by target-set discriminability.