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Joetta Gobell, Marisa Carrasco; Transient attention alters the appearance of spatial frequency.. Journal of Vision 2004;4(8):629. doi: 10.1167/4.8.629.
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Transient attention affects early visual processing, e.g., increasing spatial resolution (Yeshurun & Carrasco, 1998) by shifting sensitivity to higher spatial frequencies (SFs; Ho, Loula & Carrasco, 2002). However, it is not clear whether this is accompanied by a change in appearance of the stimulus. Here, we investigated whether transient attention changes the appearance of SF. On each trial, observers viewed a display of two gabors, one to the left and one to the right of fixation, and were required to “report the orientation of the gabor of higher SF.” One gabor was the “standard” (one of two fixed SFs) and the other was the “test” (whose SF varies in a range about the standard). The presentation of the gabors was preceded by a cue, either peripheral or neutral. The peripheral cue appeared above one of the gabors, drawing attention to that location, while the neutral cue appeared at fixation, drawing attention to neither location. The cue was not predictive of any aspect of the response-location, orientation, or SF. Results indicate that transient attention changes the appearance of SF; it increases between .2 and .3 cpd for gabors ranging from 2–8 cpd. To rule out a bias account of the results, observers completed a condition in which the cue appeared after the gabors, preventing any effect of transient attention and leaving all other aspects of the task identical. The post cue did not alter the appearance of SF. We then presented the two gabors sequentially, with a 500 ms gap between them, keeping the rest of the task unchanged. When the comparison of SF was based on encoded representations, the change in appearance was no longer present. This series of experiments demonstrates a clear change in the appearance of SF due to transient attention-transient attention creates the appearance of increased SF. This effect is not due to a cue bias, and it is not preserved in memory representations that last 500 ms or longer.
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