Rhythmic grouping in English, Greek and Korean: testing the iambic-trochaic law

The iambic-trochaic law (ITL) states that repeating sounds with an intensity contrast are perceived as binary groups with initial prominence (trochees) and those with a durational contrast with final prominence (iambs). Although the ITL has been empirically supported, it is not clear whether it is due to universal cognitive mechanisms or whether language-specific prosodic properties affect listeners’ grouping preferences. We tested the law with speakers of English, Greek and Korean who heard strings of tones varied in duration and/or intensity. The results revealed neither significant differences among languages nor a strong bias shared by speakers of all languages. Significantly, listeners’ grouping preferences were influenced by the duration of the inter-tone interval (ITI), with long ITI (200 ms) resulting in stronger trochaic preferences than short ITI (20 ms), indicating that specific experimental conditions may be responsible for cross-linguistic differences in listener responses across experiments testing the ITL.