Going on with optimised feet: Evidence for the interaction between segmental and metrical structure in phonological encoding from a case of primary progressive aphasia

Abstract

Background: Our knowledge about the interaction between segmental and metrical levels of representation in word production is still largely underspecified. In particular, there is only sparse evidence of how syllables are hierarchically organised into higher‐level prosodic structures such as prosodic feet and words. Furthermore, the question whether stress assignment in German is sensitive to syllable weight is unresolved so far. While quantity‐insensitive accounts state that stress is predominantly assigned to a default position (i.e., to the penultimate syllable) and other stress patterns are exceptional, quantity‐sensitive accounts assume that stress assignment is determined by the weight of the final two syllables.

The present investigation was supported by the German Science Foundation (project WI 853/7‐1) and by the START programme of the faculty of Medicine at the RWTH Aachen University (AZ 37/07). We would like to thank patient HT for participating in our studies, Anna‐Lisa Schelwies for her assistance in transcribing some of the data, and Ingrid Aichert for kindly providing us with syllable frequency counts.

Aims: Impaired lexical retrieval may lead to regularisations of stress assignment. Such an error pattern will be examined to gain insights into the interrelation between different tiers of prosodic representations (e.g., syllable, foot, prosodic word).

Methods & Procedures: A reading and a repetition task were conducted with German‐speaking patient HT, suffering from primary progressive aphasia, which especially affected her retrieval of lexical information. The material consisted of polysyllabic words with varying stress patterns and syllable structures.

Outcomes & Results: In reading, HT produced hardly any segmental errors, but a substantial amount of stress errors. Importantly, the patient not only over‐generalised the “default” penultimate stress as would have been predicted by quantity‐insensitive approaches. Instead, she over‐applied different stress patterns depending on the weight of the last two syllables. In repetition, HT's output can be characterised as phonological jargon. Crucially, however, she hardly produced any stress errors. Rather, thorough analyses revealed that segmental deviations in her output led to optimised prosodic structures. For instance, insertions of rhyme segments could be observed mainly in strong syllables, i.e., syllables bearing main or secondary stress, whereas deletions occurred predominantly in weak, unstressed syllables.

Conclusions: The present data provide evidence for specific forms of interaction between segmental and metrical knowledge: On the one hand, segmental information influenced the patient's stress assignment errors in reading. On the other hand, prosodic information modified segmental errors even in severe jargon observed in repetition. With respect to the prosodic system of German, the observed error patterns show that the structure of the final syllable determines how syllables of a word are parsed into prosodic feet and, accordingly, which syllable has to be prominent. Thus, our results support quantity‐sensitive approaches of stress assignment.

Keywords:

• Word stress
• Prosody
• Regularisation
• Reading
• Repetition

Notes

The present investigation was supported by the German Science Foundation (project WI 853/7‐1) and by the START programme of the faculty of Medicine at the RWTH Aachen University (AZ 37/07). We would like to thank patient HT for participating in our studies, Anna‐Lisa Schelwies for her assistance in transcribing some of the data, and Ingrid Aichert for kindly providing us with syllable frequency counts.

1. The reading task has been outlined very briefly in Janßen (2003b).

2. A pseudoword reading task also performed by HT revealed the same correlation between the structure of the final syllable and stress pattern: Pseudowords with a closed final syllable were stressed on the final syllable and pseudowords with an open final syllable on the prefinal syllable. Due to space limitations the pseudoword reading task will not be reported in more detail.

3. In the metrical theory of German it remains unresolved so far whether a stray initial syllable creates a foot on its own or is left unparsed. The assumption that such syllables form monosyllabic feet poses a problem for the avoidance of stress clash, whereas an unparsed syllable violates the constraint that demands exhaustive parsing of syllables. Further research is necessary to validate the status of the two constraints involved.