Abstract

We have previously measured the detectability of pairs of briefly flashed lines as a function of their separation in space and time. Such lines show strong facilitation over a region of space/time which is diagonally elongated and has a slope of ~1.5 deg/s. This suggests a mechanism sensitive to moving stimuli. Here we attempt to relate this finding to the actual perception of motion. We test two hypotheses: (1) We are dealing with classical motion detectors which produce the sensation of motion. (2) We are dealing with a system for resolving spatial detail in moving stimuli. To test the first hypothesis, we produced a motion aftereffect and looked for a direction-specific effect on the detection of line pairs. There was none, leading us to reject that hypothesis. To test the second hypothesis we measured the acuity for a single moving line as a function of its velocity. Acuity is sharpest in the vicinity of 2-deg/s, generally consistent with the earlier two-line detection results. This finding strengthens the second hypothesis.

© 1986 Optical Society of America