Investigating the Neural Basis of the Loud-first Principle of the Iambic–Trochaic Law

Journal of Cognitive Neuroscience · 2024

• Artificial Intelligence
• Computer Science
• Psychology

The perception of rhythmic patterns is crucial for the recognition of words in spoken languages, yet it remains unclear how these patterns are represented in the brain. Here, we tested the hypothesis that rhythmic patterns are encoded by neural activity phase-locked to the temporal modulation of these patterns in the speech signal. To test this hypothesis, we analyzed EEGs evoked with long sequences of alternating syllables acoustically manipulated to be perceived as a series of different rhythmic groupings in English. We found that the magnitude of the EEG at the syllable and grouping rates of each sequence was significantly higher than the noise baseline, indicating that the neural parsing of syllables and rhythmic groupings operates at different timescales. Distributional differences between the scalp topographies associated with each timescale suggests a further mechanistic dissociation between the neural segmentation of syllables and groupings. In addition, we observed that the neural tracking of louder syllables, which in trochaic languages like English are associated with the beginning of rhythmic groupings, was more robust than the neural tracking of softer syllables. The results of further bootstrapping and brain-behavior analyses indicate that the perception of rhythmic patterns is modulated by the magnitude of grouping alternations in the neural signal. These findings suggest that the temporal coding of rhythmic patterns in stress-based languages like English is supported by temporal regularities that are linguistically relevant in the speech signal.

Investigating the neural basis of the iambic/trochaic law

The Journal of the Acoustical Society of America · 2023

• Computer Science
• Artificial Intelligence
• Psychology

The iambic/trochaic law predicts that listeners perceive loud sounds as rhythmic group onsets. While this law provides a solid framework to investigate the perception of foot inventories across languages, its neural underpinnings are currently unknown. Here, we test the hypothesis that the segmentation of rhythmic speech patterns is driven by neural oscillations that entrain in frequency and phase to the onset of rhythmic groups and units. We recorded EEGs evoked with a sequence of “ba” and “ga” units with their intensity manipulated to be perceived as a series of “BA ga” or “GA ba” groupings. We also manipulated the duration of rhythmic groups and units to achieve a rate of 3 units and 1.5 groups per second. Participants (N = 12) were instructed to segment each sequence (“BA ga BA ga …” and “ba GA ba GA …”) multiple times while wearing an EEG cap with 32 scalpelectrodes. Individual EEG spectra exhibited group and unit peaks at 1.5 Hz and 3Hz, respectively (ps < 0.001). Additionally, individual EEGs entrained to each rhythmic group with a different phase (ps < 0.01). These results support the hypothesis that the segmentation of rhythmic speech patterns in the cortex is mediated by a temporal code driven by entrainment.

“Natural” stress patterns and dependencies between edge alignment and quantity sensitivity

Phonological Data and Analysis · 2022

• Artificial Intelligence
• Computer Science
• Cognitive psychology

We conducted an artificial language learning experiment to study learning asymmetries that might reveal latent preferences relating to, and any dependencies between, the edge aligmnent and quantity sensitivity (QS) parameters in stress patterning. We used a poverty of the stimulus approach to teach American English speakers an unbounded QS stress rule (stress a single CV: syllable) and either a left- or right-aligning QI rule if only light syllables were present. Forms with two CV: syllables were withheld in the learning phase and added in the test phase, forcing participants to choose between left- and right-aligning options for the QS rule. Participants learned the left- and right-edge QI rules equally well, and also the basic QS rule. Response patterns for words with two CV: syllables suggest biases favoring a left-aligning QS rule with a left-edge QI default. Our results also suggest that a left-aligning QS pattern with a right-edge QI default was least favored. We argue that stress patterns shown to be preferred based on evidence from ease-of-learning and participants’ untrained generalizations can be considered more natural than less favored opposing patterns. We suggest that cognitive biases revealed by artificial stress learning studies may have contributed to shaping stress typology.

The iambic/trochaic law: Nature or nurture?

Language and Linguistics Compass · 2019-12-18 · 42 citations

Abstract The iambic/trochaic law (ITL) asserts that listeners associate louder sounds with group onsets and longer sounds with group endings. The ITL has interested theoretical phonologists since Hayes' (1995) proposal that it may describe the perceptual underpinnings of the Foot Inventory (Hayes, 1995; McCarthy and Prince, 1986, 1996). This article surveys the growing experimental literature exploring perceptual ITL effects. The experimental findings to date suggest that ITL effects have both a “nature” and a “nurture” component, are documented for a variety of species, and are cross‐modal in humans. Questions are raised as to whether there is likely to be a natural connection between ITL effects and the foot inventory.

The joint influence of vowel duration and creak on the perception of internal phrase boundaries

The Journal of the Acoustical Society of America · 2018-03-01 · 8 citations

Lengthening and creaky voice are associated with prosodic finality in English. Listeners can use lengthening to identify both utterance-internal and final prosodic phrase boundaries and can use creak to locate utterance endings. Less is known about listeners' use of creak to locate internal prosodic boundaries and the relative importance assigned to duration and creak when both are present. Participants in two experiments segmented structurally ambiguous sentences in which duration and creak were manipulated to signal prosodic boundaries. When duration- and creak-based cues provided redundant information, their effects were additive. When these cues conflicted, the effect of creak was subtractive.

The influence of varying vowel phonation and duration on rhythmic grouping biases among Spanish and English speakers

Journal of Phonetics · 2017-10-20 · 19 citations

The influence of vowel laryngealisation and duration on the rhythmic grouping preferences of Zapotec speakers

Journal of Phonetics · 2016-07-05 · 9 citations

Iambic-Trochaic Law Effects among Native Speakers of Spanish and English

Laboratory Phonology Journal of the Association for Laboratory Phonology · 2016-10-07 · 15 citations

The Iambic-Trochaic Law (Bolton, 1894; Hayes, 1995; Woodrow, 1909) asserts that listeners associate greater intensity with group beginnings (a loud-first preference) and greater duration with group endings (a long-last preference). Hayes (1987; 1995) posits a natural connection between the prominences referred to in the ITL and the locations of stressed syllables in feet. However, not all lengthening in final positions originates with stressed syllables, and greater duration may also be associated with stress in nonfinal (trochaic) positions. The research described here challenged the notion that presumptive long-last effects necessarily reflect stress-related duration patterns, and investigated the general hypothesis that the robustness of long-last effects should vary depending on the strength of the association between final positions and increased duration, whatever its source. Two ITL studies were conducted in which native speakers of Spanish and of English grouped streams of rhythmically alternating syllables in which vowel intensity and/or duration levels were varied. These languages were chosen because while they are prosodically similar, increased duration on constituent-final syllables is both more common and more salient in English than Spanish. Outcomes revealed robust loud-first effects in both language groups. Long-last effects were significantly weaker in the Spanish group when vowel duration was varied singly. However, long-last effects were present and comparable in both language groups when intensity and duration were covaried. Intensity was a more robust predictor of responses than duration. A primary conclusion was that whether or not humans’ rhythmic grouping preferences have an innate component, duration-based grouping preferences, at least, and the magnitude of intensity-based effects are shaped by listeners’ backgrounds.

Beyond the Iambic-Trochaic Law: the joint influence of duration and intensity on the perception of rhythmic speech

Phonology · 2014-05-01 · 31 citations

The Iambic-Trochaic Law (ITL) asserts that listeners associate greater acoustic intensity with group beginnings and greater duration with group endings. Some researchers have assumed a natural connection between these perceptual tendencies and universal principles underlying linguistic categories of rhythm. The experimental literature on ITL effects is limited in three ways. Few studies of listeners' perceptions of alternating sound sequences have used speech-like stimuli, cross-linguistic testing has been inadequate and existing studies have manipulated intensity and duration singly, whereas these features vary together in natural speech. This paper reports the results of three experiments conducted with native Zapotec speakers and one with native English speakers. We tested listeners' grouping biases using streams of alternating syllables in which intensity and duration were varied separately, and sequences in which they were covaried. The findings suggest that care should be taken in assuming a natural connection between the ITL and universal principles of prosodic organisation.

Vowel-Rhotic Metathesis in Guarayu

International Journal of American Linguistics · 2014-03-20 · 5 citations

Guarayu (Tupí-Guaraní, Bolivia) has undergone a diachronic process of metathesis in which a word-final tap /ɾ/ exchanged positions with a preceding high nonfront vowel /ɨ/ or /u/. We propose a scenario for how such an exchange could occur, using Guarayu as a case study. A tap/vowel metathesis is presented as a timing readjustment that led to an exchange of phonemic status between a phonemic vowel on one side of the tap and an automatic intrusive vowel on the other. We suggest that, in Guarayu, this realignment may have been facilitated by an insufficiency of phonetic cues that a listener might routinely use to accurately perceive and locate the transition between the vowel and tap involved in the exchange. We propose that phonological factors also played a role and that metathesis was perception optimizing, and we report the results of a speech perception experiment that supports this interpretation. Connections are drawn between the Guarayu metathesis and patterns of vowel epenthesis and deletion known to occur as alternatives to metathesis in other languages.