Abstract
The present study consisted of two experiments. The goal of the first
experiment was to establish the just noticeable differences for the
fundamental frequency of the vowel /u/ by using the 2AFC method. We
obtained the threshold value for 27 cents. This value is larger than the
motor reaction values which had been observed in previous experiments
(e.g. 9 or 19 cents). The second experiment was intended to provide
neurophysiological confirmation of the detection of shifts in a frequency,
using event-related potentials (ERPs). We concentrated on the mismatch
negativity (MMN) - the component elicited by the change in the pattern of
stimuli. Its occurrence is correlated with the discrimination threshold.
In our study, MMN was observed for changes greater than 27 cents - shifts
of ±50 and 100 cents (effect size - Cohen’s d = 2.259). MMN did not appear
for changes of ±10 and 20 cents. The results showed that the values for
which motor responses can be observed are indeed lower than those for
perceptual thresholds.
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