ERIC Number: ED223248
Record Type: Non-Journal
Publication Date: 1980
Reference Count: N/A
Effects of Spatial Position and Density on Visual Acuity. Umea Psychological Reports No. 153.
Visual acuity as a function of target position and density was measured in a letter recognition task. A homogeneous pattern of equally-spaced elements was tachistoscopically exposed, where the target was never located at the boundaries of the pattern. The target was marked with a spatial cue to control attentional processes. With such a spatial arrangement, acuity should decrease with the increased distance of the acuity of the target from the fovea. The experiment involved the presentation of multi-letter displays varying in density, using a two-channel tachistoscope. The subjects' task was to identify an encircled target letter whose spatial position was varied across the displays. By controlling the subjects' attention and positional preferences and by avoiding end-effects for the dense displays, it was shown that acuity declined linearly with target distance for the densities 0, 5, and 10 elements per square degree. Density affected the acuity function's slope by making it steeper, while increasing density from 5 to 10 elements did not affect the slope further, suggesting that density only affects general visual load. Confidence ratings collected in the same experiment confirmed the recognition data. This report includes 12 references. (Author)
Publication Type: Reports - Research
Education Level: N/A
Sponsor: Swedish Council for Social Science Research, Stockholm.
Authoring Institution: Umea Univ. (Sweden).