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S I Shih

Publications and source records attributed to S I Shih.

2 recordsLinked to original sources

Recall of two visual targets embedded in RSVP streams of distractors depends on their temporal and spatial relationship.

In the present study, I examined how the temporal and spatial relationship between two visual targets (T1 and T2) affects the recall of both targets when they are embedded in rapidly displayed distractors. Presented on a trial were two synchronized streams of characters, one to the left and the other to the right of the fixation. Independent of their spatial relationship, a U-shaped curve described the recall of the second target (T2) as a function of stimulus onset asynchrony (SOA) between T1 and T2. It indicated the presence of the attentional blink with a T2 deficit sparing up to about 150- to 200-msec SOA. However, T2 deficit was greater at short SOAs (up to about 250 msec) when T1 and T2 occurred at different locations than when they occurred at a common location. When SOA was short (100 msec or so), recall of T1 was impaired when T1 and T2 occurred at a common location, but not when they were at different locations. The present findings can be reconciled with existing models (e.g., the interference model and the two-stage model) by distinguishing automatic and controlled attention gating processes at the transfer of perceptual representations to a more durable storage (e.g., visual short-term memory).

Adult↗

Is there feature-based attentional selection in visual search?

A new paradigm combines attentional cuing and rapid serial visual presentation to disentangle the effects of perceptual filtering and location selection. Observers search successive, superimposed arrays, in which feature values are alternated for a target numeral among letters. Two dimensions, size (small, large) and color (red, green) are tested. Selective attention to feature values is jointly manipulated by instructions, presentation probabilities, and payoffs. In Experiment 1, the attended feature provides temporal, not spatial, information; observers show no attentional costs or benefits in response accuracy. In Experiment 2, the attended feature indicates a unique location; observers show consistent attentional costs and benefits. Selective attention to a particular size or color does not cause perceptual exclusion or admission of items containing that feature; it acts by guiding search processes to spatial locations that contain the to-be-attended feature.

Attention↗