During pre- and post-tests participants performed a 3-dot Vernier task and a 3-dot bisection task. During training participants performed a luminance
discrimination task on the same 3-dot stimulus. The task-irrelevant feature of the stimulus manipulated during training was the position of the middle dot. Our results suggest that perceptual learning can occur as a result of mere exposure to a subthreshold and task-irrelevant feature of the stimulus. The present findings add new evidence in support of task-irrelevant PL, which seems to occur not only when two different stimuli are used during test and training, but also when the same stimulus is used in both stages.
