  Visuospatial attention and gaze control depend on the interaction of foveal
and peripheral processing. The foveal and peripheral regions of the visual
field are differentially sensitive to parts of the spatial-frequency spectrum.
In two experiments, we investigated how the selective attenuation of spatial
frequencies in the central or the peripheral visual field affects eye-movement
behavior during real-world scene viewing. Gaze-contingent low-pass or high-pass
filters with varying filter levels (i.e., cutoff frequencies; Experiment 1) or
filter sizes (Experiment 2) were applied. Compared to unfiltered control
conditions, mean fixation durations increased most with central high-pass and
peripheral low-pass filtering. Increasing filter size prolonged fixation
durations with peripheral filtering, but not with central filtering. Increasing
filter level prolonged fixation durations with low-pass filtering, but not with
high-pass filtering. These effects indicate that fixation durations are not
always longer under conditions of increased processing difficulty. Saccade
amplitudes largely adapted to processing difficulty: amplitudes increased with
central filtering and decreased with peripheral filtering; the effects
strengthened with increasing filter size and filter level. In addition, we
observed a trade-off between saccade timing and saccadic selection, since
saccade amplitudes were modulated when fixation durations were unaffected by
the experimental manipulations. We conclude that interactions of perception and
gaze control are highly sensitive to experimental manipulations of input images
as long as the residual information can still be accessed for gaze control.
