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Yaffa Yeshurun; Motion perception is differentially effected by the transient and sustained components of spatial attention. Journal of Vision 2005;5(8):141. doi: 10.1167/5.8.141.
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© ARVO (1962-2015); The Authors (2016-present)
Many have suggested that spatial attention has 2 components: The slower, voluntary Sustained Attention (SA), and the faster, involuntary Transient Attention (TA). Whether these two components are separate mechanisms operating in a different manner, or just different instantiations of the same mechanism is still unclear.
To study the effects of TA on motion perception observers in one task had to rate the quality of motion perception elicited by an apparently moving line, and to indicate in another task the motion direction of an apparently moving rectangle. A peripheral cue (a bar) known to attract TA to the target location, or a neutral cue (6 bars) specifying that the target could appear in any one of the 6 possible locations, preceded the target. The results indicate that TA degrades motion perception. Motion rates and direction discrimination were lower with the peripheral than the neutral cues. This degradation was found even with a color-singleton cue, identical in all aspects to the neutral cue apart for the color of the bar above the target location, ruling out any ‘interference’ interpretations of the results. These results are consistent with other findings regarding TA and temporal processes and support the hypothesis that TA favors parvocellular over magnocellular activity.
This attentional degradation disappears, however, with SA cues. In two additional experiments, centrally presented cues preceded the apparently moving rectangle. One cue was an arrow pointing at the target location. The other was a face gazing at the target location. In both cases, no attentional degradation of motion perception was found, and a small facilitation was evident with spatial displacement larger than 1°. This is consistent with previous studies showing that SA either improves motion perception or does not affect it (especially with small displacements). The differential effects of the two components of spatial attention support the view that TA and SA are indeed two different mechanisms.
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