Fig 1.
Half the melodies were in-tune, 25% were out-of-tune and 25% were out-of-key. The out-of-tune and out-of-key melodies were created by altering the last note of the in–tune melodies, by shifting them by either 50 cents (out-of-tune) or 100 cents (out-of-key). In the melodic task, participants judged whether a melody contained an incongruous note. Their judgment as well as their level of confidence were recorded for each trial on a four point scale (1-congruous, sure; 2-congruous, not sure; 3-incongruous, not sure; 4-incongruous, sure).
Fig 2.
The non-melodic task consisted of four-tone sequences. The 4th tone was either: identical to the preceding ones (25% of the trials); shifted by 6.25 cents (25% of the trials); shifted by 12.50 cents (25% of the trials); or shifted by 50 cents (25% of the trials). Participants judged whether the 4th tone was higher or lower in pitch than the preceding tones. Judgment and confidence level were recorded on a four-point scale (1-higher, sure; 2-higher, not sure; 3-lower, not sure; 4-lower, sure).
Fig 3.
Behavioral results for the melodic task.
Participants’ (A) accuracy (% correct), (B) confidence (% sure) and (C) reaction time (ms) for the melodic task. Results are presented as a function of experimental condition (i.e. in-tune, out-of-key, out-of-tune).
Fig 4.
Behavioral results for the non-melodic task.
Participants’ (A) accuracy (% correct), (B) confidence (% sure) and (C) reaction time (ms) for the non-melodic task. Results are presented as a function of experimental condition (i.e. Identical, 6.25, 12.50 and 50 cents). For the Identical condition in panel (A), accuracy reflects the proportion of “higher in pitch” responses, and thus accuracy of 50% is indicative of non-biased responses.
Fig 5.
Activation maps to deviants in non-melodic and melodic contexts.
(A) Activation map for the 50 cents > Identical contrast from the non-melodic task. A mask was applied to highlight activation in the superior temporal gyrus (STG) for visualization purposes. (B) Activation map for the Out-of-tune > In-tune from the melodic task. In the top image, a mask was applied to highlight activation in the STG, and in the bottom image, a mask was applied to highlight activity in supramarginal gyrus/inferior parietal lobule (IPL). Scale represents t-values.
Fig 6.
Brain regions responding more strongly to the melodic task compared to the non-melodic task.
Activation map for the (Non-melodic: 50 cents > identical) > (Melodic: Out-of-tune > In-tune). A mask was applied to highlight activation in the supramarginal gyrus/inferior parietal lobule (IPL) for visualization purposes. Scale represents t-value.
Table 1.
Melodic task: Out-of-tune > In-tune.
Table 2.
Non-melodic task: 50 cents > Identical.
Table 3.
Non-melodic task: 12.5 cents > Identical.
Table 4.
Melodic pitch discrimination (Melodic [Out-of-tune > In-tune] > Non-melodic [50 cents > Identical]).