Imagined lines fail to induce contour masking

Twelve Ss proficient in visual imagery were tested in a study to compare contour masking by real and imaginary lines. Detection of a vertical line was impaired following inspection of a vertical grating but was unaffected by exposure to a horizontal grating. When Ss were required to imagine a dot pattern as either a vertical or horizontal grating prior to judging whether a vertical line was present or absent in the display, the orientation that S was instructed to imagine did not influence detection of the target. This evidence that specific visual imagery does not mask a dimensionally similar visual target is contrasted with other data indicating that isomodal masking occurs when complex visual and auditory imagery and target stimuli are used.