Vernier acuity: interactions between length effects and gaps when orientation cues are eliminated.

It is shown that Vernier acuity is nearly proportional to line length (in the range 5-20 arc min), provided that the orientation of the target is randomized from trial to trial and provided that no gap interrupts the line. The effect of a pair of gaps, one in each of the Vernier bars leads to the conclusion that line terminations dissect the target into independent parts prior to the visual analysis of shape and orientation cues, which are only assessed between such features.

RCT Entities:   Population Interventions Outcomes