An account of the Speech-to-Song Illusion using Node Structure Theory

Abstract

In the Speech-to-Song Illusion, repetition of a spoken phrase results in it being perceived as if it were sung. Although a number of previous studies have examined which characteristics of the stimulus will produce the illusion, there is, until now, no description of the cognitive mechanism that underlies the illusion. We suggest that the processes found in Node Structure Theory that are used to explain normal language processing as well as other auditory illusions might also account for the Speech-to-Song Illusion. In six experiments we tested whether the satiation of lexical nodes, but continued priming of syllable nodes may lead to the Speech-to-Song Illusion. The results of these experiments provide evidence for the role of priming, activation, and satiation as described in Node Structure Theory as an explanation of the Speech-to-Song Illusion.

Fig 1. Depiction of the word frisbee according to Node Structure Theory.

Adapted from Fig 1 in [17]. A simplified depiction of the network connections for the word frisbee, including higher-level sentential connections and lower-level phonological connections.

Fig 2. Speech-to-Song ratings of dense and sparse word-lists dependent on repetition condition.

Ratings were made on a scale from 1 (sounds like speech) to 5 (sounds like song) for dense and sparse word-lists in three repetition conditions (no repetition, repetition with pauses, and repetition without pauses). Mean ratings for each condition are listed above each column, with whiskers representing standard error of the mean.

Fig 3. Speech-to-Song ratings of low and high phonotactic probability word-lists dependent on repetition condition.

Ratings were made on a scale from 1 (sounds like speech) to 5 (sounds like song) for low and high phonotactic probability word-lists with and without repetition. Mean ratings for each condition are listed above each column, with whiskers representing standard error of the mean.

Fig 4. Plot of Speech-to-Song ratings dependent on the number of words per list.

Spaghetti plot highlights the quadratic effect of the number of words on Speech-to-Song ratings for each participant. Blue lines represent each individual’s trajectory with the black line representing the average of all individuals.

Fig 5. Plot of Speech-to-Song ratings dependent on the number of syllables per list.

Spaghetti plot highlights the linear effect of the number of syllables on Speech-to-Song ratings for each participant. Blue lines represent each individual’s trajectory with the black line representing the average of all individuals.