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Joseph L. Sanguinetti, Logan T. Trujillo, David M. Schnyer, John J. B. Allen, Mary A. Peterson; Increased alpha band activity indexes inhibitory competition across a border during figure assignment. Journal of Vision 2014;14(10):49. doi: 10.1167/14.10.49.
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© ARVO (1962-2015); The Authors (2016-present)
Prior research shows that increased activity in the alpha band of the EEG may index inhibition of competing information when covert attention is directed to one hemifield and the distracting stimulus is in the other. Here we tested whether increased alpha activity indexes inhibitory competition for figural status. Across 3 experiments, participants viewed real world or novel silhouettes and made "real-world/novel" judgments. Real world silhouettes (n = 40) depicted namable objects. There were two types of novel silhouettes; both depicted novel objects on the inside of their borders. Low competition silhouettes (n = 40) suggested novel objects on the outside of their borders as well. High competition silhouettes (n = 40) suggested portions of real-world objects on their outside, groundside; critically, participants saw the inside as figure and were unaware of the suggested real-world objects on the groundside. Nevertheless there is more cross-border competition for figural status in high- versus low-competition silhouettes. With more competition there should be more inhibition of the object suggested on the groundside. Therefore we predicted an increase in alpha power for high- versus low-competition silhouettes. In Experiment 1, each silhouette was presented once within a single block (4 blocks total). In Experiment 2 single repetitions occurred within 18-21 intervening items within a single block. In these experiments we found increased alpha power in the predicted direction (p <.05) collapsing across repetitions. Experiment 3 used shorter lags (4-7 intervening items). Here alpha power was reduced for second versus first presentation of high competition silhouettes only (p <.05), suggesting that inhibition of the object suggested on the groundside persists for a short time and reduces competition on the second presentation. These results demonstrate for the first time that increases in alpha activity can be used to measure inhibitory competition across a border during figure assignment.
Meeting abstract presented at VSS 2014
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