PERCEPTUAL-LEARNING IN VERNIER ACUITY - WHAT IS LEARNED

It has been suggested that the improvement of vernier acuity in the co urse of practice reflects ''fine tuning'' of the visual mechanisms und erlying vernier acuity. Masking studies suggest that an important sour ce of information by which the visual system may accomplish fine verni er acuity is the activity in orientation tuned channels. Therefore, we investigated whether improvement in vernier acuity after training was accompanied by systematic changes in the orientation tuning character istics of vernier acuity (as revealed by simultaneous spatial noise ma sking). The results show large interindividual variation in learning v ernier acuity. However, they reveal a close correspondence between the improvement in vernier acuity and the narrowing of the orientation tu ning function. Thus, the results provide some support for the notion o f narrowing of the orientation characteristics of vernier acuity in th e course of learning.