Detection of Dotted Forms in a Structured Visual Noise Environment.

Five experiments are described which explore the human observer's ability to detect single dotted lines masked by other dotted lines. Stimuli are presented tachistoscopically on a computer controlled cathode ray tube. Results indicate that: Rotations of the stimuli, relative to the orientation of the noise lines, improve detection performance only if the rotations are made around the Z axis. Rotations around the Y axis fail to improve detection performance. The mechanism involved in the detection of dotted forms uses different strategies or algorithms depending upon the density of the noise mask. Orienting the stimulus and masking lines to other than the horizontal decreases detection performance. The results are discussed in the context of model incorporating a variable aperture attentional process. (Author)