This contribution deals with two major issues on visual/spatial attention. One is the issue of facilitation and inhibition; that is, under what conditions facilitatory modulation occurs, and under what other conditions inhibitory modulation occurs. The other issue is that of spatial representation; in what type of spatial representation do these modulations occur, retinotopic or environmental? In the first half of this article, we review the latest studies employing various psychophysical measures to assess spatially-selective modulation of visual information processing. We also summarize our latest results on reaction time, indicating a dissociation of two visual functions, detection/orientation and feature discrimination. Based on these chunks of knowledge, we raise a question about the spatial coordinate system in which the facilitatory and/or inhibitory modulations occur. We then provide results of two reaction-time experiments which partly answer the question.
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