Auditory stroop and absolute pitch: an fMRI study

Abstract

To date, the underlying cognitive and neural mechanisms of absolute pitch (AP) have remained elusive. In the present fMRI study, we investigated verbal and tonal perception and working memory in musicians with and without absolute pitch. Stimuli were sine wave tones and syllables (names of the scale tones) presented simultaneously. Participants listened to sequences of five stimuli, and then rehearsed internally either the syllables or the tones. Finally participants indicated whether a test stimulus had been presented during the sequence. For an auditory stroop task, half of the tonal sequences were congruent (frequencies of tones corresponded to syllables which were the names of the scale tones) and half were incongruent (frequencies of tones did not correspond to syllables). Results indicate that first, verbal and tonal perception overlap strongly in the left superior temporal gyrus/sulcus (STG/STS) in AP musicians only. Second, AP is associated with the categorical perception of tones. Third, the left STG/STS is activated in AP musicians only for the detection of verbal-tonal incongruencies in the auditory stroop task. Finally, verbal labelling of tones in AP musicians seems to be automatic. Overall, a unique feature of AP appears to be the similarity between verbal and tonal perception.

Figure 1

Performance in two AP test for AP and non‐AP musicians. Chance level was 25% (answers within one semitone of the presented pitch were regarded as a correct answer; see Materials and Methods).

Figure 2

Experimental conditions. Verbal and tonal condition: Each auditory stimulus comprised of a spoken syllable and a simultaneously presented sine wave tone. The frequencies of the sine wave tones corresponded to the frequencies of the tones of the Western chromatic scale. The syllables were the spoken German names of the scale tones (e.g., gis [g‐sharp], c, etc.). Congruent and incongruent condition: In 50% of the sequences the frequency of the sine wave tones corresponded to the simultaneously presented syllables (congruent sequences) and in the remaining 50% of sequences, the frequency of the sine wave tones did not correspond to the syllables (incongruent sequences). Congruent and incongruent conditions were only compared during the tonal condition.

Figure 3

WM performance (in % correct responses) for AP and non‐AP musicians presented as a function of sequence type (congruent/incongruent)—error bars indicate the standard error of mean (SEM).

Figure 4

Significant differences are shown with blue (A) or red/yellow (B–D) color‐coding using a cluster threshold of P < 0.05, corrected. A – Interaction contrast: difference verbal—tonal was compared between AP and non‐AP musicians. B – Stronger activation of left STG/STS during verbal compared to tonal perception in non‐AP musicians. C – Interaction contrast: difference incongruent – congruent perception has been compared between AP and non‐AP musicians. D – Stronger activation of left STG/STS during incongruent compared to congruent perception in AP musicians.