Abstract
Purpose: :
Perceptual learning improves positional acuity. The present experiment was aimed at investigating the effect of perceptual learning on bisection acuity and specifically, whether the learning, if any, transfers from static to moving stimuli and to different configural orientations.
Methods: :
The bisection stimulus comprised of 3 briefly presented (300ms) adjacent square dots (2x2 arcmin, black dots on a gray background 70cd/m2) separated by 5 arcmin. The observer’s task was to localize the position of the central dot relative to the adjacent dots. The experiment was conducted in 6 phases. On day 1, the pre-training session consisted of 6 stimulus conditions: [1] static horizontal orientation, [2] static oblique (45 deg) orientation, [3] oblique stimulus moving in an orthogonal direction (135 deg) at 2 deg/s, and [4-6] oblique stimulus moving along 45 degree at three different speeds (1.33, 2.00, 2.66 deg/s). Observers practiced the task with the static oblique stimulus from day 2 to 8, subsequently with the moving oblique stimulus (2.00 deg/sec) from day 10 to 16, and finally with the static horizontal stimulus from day 18 to 24. Performance for all six conditions was re-evaluated in two post-training sessions on days 9 and 17. Each training session consisted of 420 responses (11340 trials in total).
Results: :
Bisection acuity improved significantly (≈ 40%) after practicing with the static oblique stimulus. Learning transferred substantially to the untrained static horizontal stimulus (27% improvement) and the four untrained moving oblique stimuli (37-45% improvement). Subsequent practice with the oblique stimulus in motion (2 deg/s) resulted in a further 18% improvement in dynamic bisection acuity (a total of 55% from day 1), and the performance for both lower and higher speed stimuli improved as well. Further practice with the static horizontal stimulus resulted in an additional 16% improvement in bisection acuity (a total of 43% from day 1).
Conclusions: :
Our findings characterize the specificity of learning a bisection acuity task and show that the learning generalizes substantially, but not completely, from static to moving stimuli, and across different stimulus speeds and configural orientations.
Keywords: plasticity • pattern vision • motion-2D