JUST-NOTICEABLE DIFFERENCE IN THE SPEED OF CYCLOPEAN MOTION IN-DEPTH AND THE SPEED OF CYCLOPEAN MOTION WITHIN A FRONTOPARALLEL PLANE

Weber fractions for discriminating the speed and displacement of a cyc lopean target moving in depth ranged, respectively, from .07-.17 and . 06-.13 over 6 observers. Corresponding data for a noncyclopean target were .07-.20 and .06-.12. For motion parallel to the frontal plane, co rresponding data were .09-.20, .06-.16, .07-.16, and .05-.13. All Webe r fractions were independent of the direction of motion and of near ve rsus far disparity. All observers based their judgments entirely on th e task-relevant variable and ignored task-irrelevant variables in all cases. We conclude that speed and displacement are encoded independent ly and in parallel for motion in depth and for motion within a frontop arallel plane.