Fig. 1.

Experimental methods, stimuli, and data analysis. A: the experiment involved 7 perceptual tests. Baseline perceptual tests (PT1 and PT2) were followed by perceptual training (PT3 to PT5), a transfer test (PT6), and an aftereffect test (PT7). The order of the baseline tests was balanced across participants. B: the perceptual continua used in the experiment are depicted by their first formant (F1) and second formant (F2) values. One continua spanned the distinction between “head” and “had” (black dots), and one spanned the distinction between head and “hid” (gray dots). C: perceptual change was assessed by measuring the proportion of had and hid responses for each stimulus in each perceptual test (top). Perceptual change was also examined by measuring the time it took participants to respond to the stimuli (bottom). Reaction times were log normalized and displayed as z-scores.