Attention alters the appearance of spatial frequency and gap size.

Transient attention is the automatic and short-lasting preferential processing of an area in visual space initiated by sudden stimulation in the same vicinity. Transient attention enhances early visual processing in a variety of dimensions, increasing contrast sensitivity, spatial resolution, and acuity. A recent study established that the increase in contrast sensitivity is accompanied by an increase in apparent contrast. In the present study, we investigated whether the effects of transient attention on spatial resolution and acuity are accompanied by corresponding phenomenological changes in these dimensions. The data indicate that transient attention increases the apparent spatial frequency of Gabor stimuli (Experiment 1) and increases apparent gap size in a Landolt-square acuity task (Experiment 2). Transient attention not only affects basic visual processing-it changes what one experiences.