Conditioning human observers with an “artificial
scotoma”—a small retinal area deprived of patterned
stimulation within a larger area of dynamically textured
noise—results in contractions and expansions of perceived space
that are thought to reflect receptive-field changes among cells in the
primary visual cortex (Kapadia et al., 1994).
Here we show that one-dimensional counter-phase flickering grating
patterns are also potent stimuli for producing artificial scotomata
capable of altering three-element bisection ability analogous to those
results reported earlier. Moreover, we found that the magnitude of the
induced spatial distortions depends critically on the relative
orientations of peri-scotomatous and test-stimulus spatial contrast. In
addition, the perceptual distortions are found to be relatively short
lived, decaying within 660 ms. The results support the hypothesis that
artificial scotoma-induced perceptual distortions are generated by
dynamic alteration of connection efficacy within a network linking
cortical areas of similar orientation specificity, consistent with
established anatomical and physiological results.