Figure 1.

Phase-Dependent Suppression of Contrast Sensitivity at the Leading Edge of a Moving Stimulus

(A) Stimulus configuration. Observers were required to indicate whether a small target pattern was presented to the left or right of fixation. Two high-contrast inducer gratings were positioned adjacent to the potential target locations. Each drifted in the same direction and at the same speed as the target. Manipulation of the stimulus configuration allowed comparison of performance when the target was positioned at either the trailing (red box) or leading (black box) edge of the inducer.

(B) Space-time plots depicting different phase relationships between inducing (high-contrast region) and target (low-contrast region) stimuli. Note that in-phase(0 or 2π) targets are consistent with a continuation of the inducer waveform in space and time, albeit at a lower contrast.

(C) Detection thresholds for trailing-edge (red symbols) and leading-edge (black symbols) conditions, plotted as a function of the relative phase of target and inducer stimuli. Open symbols indicate thresholds for a baseline condition with no inducers present. The mean performance of five observers is displayed in the upper left panel, with the remaining panels showing individual data. Error bars indicate ± 1 standard error, calculated either across observers (mean plots) or via bootstrapping (individual thresholds).

See also Figure S1.