Consequences of schwa alternation for word recognition

In this work, we will mostly be interested in the representations and mechanisms underlying the production of schwa words. However, given the assumption that recognition and production systems are neither drastically different nor completely unrelated, the way the recognition system copes with this type of variation is likely to provide us with useful information about the production process as well.

The consequences of French schwa alternation for the recognition process have been investigated in several studies. Racine and Grosjean (2000, see also Matter, 1989) examined the recognition of bisyllabic words with an optional schwa in their first syllable (e.g., pelouse ‘lawn’) by means of a repetition and a lexical decision task. Schwa and non-schwa variants were preceded by the possessive determiner son or sa ‘his/her’ depending on the noun’s grammatical gender. In both tasks, they find that the recognition is delayed for non-schwa variants.

In a subsequent study, Racine and Grosjean (2005) compared the recognition of three different types of schwa words: words with an optional schwa, words with an obligatory schwa (i.e., schwa is always realized, as in tournesol ‘sun flower’) and words with a forbidden schwa (i.e., graphic “e” never realized in standard French, e.g., casserole ‘pot’).

They again find an advantage for schwa variants for words with an optional schwa and show that the same advantage holds for words with an obligatory schwa. In contrast, words with a forbidden schwa show no difference in reaction times between schwa and non-schwa variants. Hence, even though speakers never use the schwa variant for these words, its recognition does not take longer than the recognition of the non-schwa variant. According to Racine and Grosjean (2005), an influence of the orthographic representation could explain this result, since the schwa is present in the spelling of these words.

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Spinelli and Gros-Balthazard (2007) further showed that phonotactic knowledge could be used to facilitate the recognition of non-schwa variants in French. They compared the recognition of schwa words’ variants with a legal onset cluster (as in semaine ‘week’) with that of schwa words with an illegal onset cluster (i.e., non-existing cluster in non-schwa words, as in genou ‘knee’) by means of a cross-modal priming experiment. Visual target words (e.g., SEMAINE, ‘week’) were preceded by an auditory presentation of either the schwa (e.g., [smn]) or the non-schwa variant (e.g., [smn]) of the target word. Spinelli and Gros-Balthazard observed a processing cost when the target word was primed by the non-schwa variant compared to the non-schwa variant, but only when the initial cluster of the target word’s non-schwa variant is legal in French. According to these authors, this result suggests that phonotactic constraints help listeners to restore the canonical variant (i.e., the schwa variant).

In sum, all existing French studies lead to the conclusion that schwa words are represented lexically with one entry, corresponding to the schwa variant. A mechanism of inference is stipulated to account for the recognition of schwa variants. Upon presentation of a non-schwa variant, the canonical form is inferred or restored. Before such an interpretation can be confirmed, we believe that the role of two additional variables should be investigated:

variant frequency and context. Variant frequency has been shown to influence reaction times in the recognition of schwa words in English (Connine, Ranbom & Patterson, 2008) as well as in that of several other phonological variation processes (e.g., nasal flap in American English, Ranbom & Connine, 2007). The influence of variant frequency on the recognition of French schwa words has not yet been investigated. In her discussion of Racine and Grosjean’s (2005) results, Racine (2008) suggests that this variable could well play a role.

Unfortunately, Racine and Grosjean’s experimental design does not allow us to draw conclusions on this specific matter.

Concerning the role of contextual factors, we know from descriptive linguistic studies that the properties of the context in which the schwa words are produced have a great impact on the alternation process. For instance, schwa variants are more frequent at slow speech rates (Racine & Grosjean, 2002; Hansen, 1994; Delattre, 1966), in formal situations (e.g., Léon, 1971) or in isolation (Fouché, 1956). So far, existing experimental studies have all provided contexts in which the schwa variant is more appropriate than the non-schwa variant. We thus cannot be certain that the systematic advantage for schwa variants obtained in these studies is not at least partly due to this contextual bias.

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The recognition of schwa and non-schwa variants has also been investigated in other languages. In Dutch, Kuijpers, van Donselaar and Cutler (1996) investigated the recognition of phonological variants derived from two different processes; schwa epenthesis and schwa deletion, by means of a lexical decision task. They found that in schwa epenthesis, the phonological variant is processed faster and more accurately than the canonical form (i.e., the non-schwa variant). In contrast and similarly to French, phonological variants resulting from schwa deletion are processed with more time and less accurately than canonical forms (i.e., schwa variants). According to the authors, these results suggest that recognition is sensitive to the CV structure of the items⁴. They do not however question the fact that the lexical representation corresponds to the non-schwa variant in schwa epenthesis and to the schwa variant in schwa deletion.

In another study on schwa epenthesis, van Donselaar, Kuijpers and Cutler (1999) showed that in a word-reversal task (i.e., participants are asked to inverse the syllables of the items), participants treat both variants (i.e., with and without schwa) as if they were non-schwa variants. In contrast, in a word spotting task (i.e., participants hear pseudowords, some of which containing embedded words that they have to detect) and a lexical decision task, they found an advantage for schwa variants (i.e., words with an epenthesis). The authors conclude that both variants activate the same canonical representation, i.e., the form without epenthesis, but that the presence of schwa leads to a better perception of the first member of the cluster in epenthetic forms. The perception of liquid consonants, otherwise hard to perceive, is made easier, which explains the advantage for schwa variants over non-schwa variants.

LoCasto and Connine (2002) examined the recognition of schwa words in English. They first showed that non-schwa variants of bi- and trisyllabic words are rated as less acceptable than schwa-reduced variants. The differences in the ratings for the two variants are even greater for bisyllabic words. They further showed different patterns for bi and trisyllabic words in a phonological priming experiment. Participants were presented with productions of schwa and non-schwa variants, primed either by themselves (repetition prime), the alternative variant (variant prime) or an unrelated word. Lexical decisions for schwa and non-schwa variants of trisyllabic words showed greater priming when the target was

4 It must be noted that statistical evidence is not fully convincing in these experiments. Analyses of variance in a given experiment are only significant per word or per participant, never both.

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preceded by itself than by the alternative variant. For bisyllabic words, schwa variants also showed greater priming when preceded by themselves but non-schwa variants were equally primed by both variant types. According to the authors, these results suggest that the lexical representation of both types of words (i.e., bi and trisyllabic words) includes the schwa. In order to account for the differences in the results for bi and trisyllabic words, they assume that the amount of redundant information is sufficient in trisyllabic words to trigger correct word recognition, but is insufficient in bisyllabic words. A process of phonological inference is thus needed for these words in order to facilitate the recognition process.

In their study of the recognition of English bisyllabic schwa words (i.e., words with a schwa in their first syllable), Utman, Blumstein and Burton (2000) find different results. Using an auditory priming paradigm, they find that lexical decisions to schwa variants primed by non-schwa variants are faster than lexical decisions to the same variants primed by themselves.

Utman et al. suggest that this increase in priming might be due to differences in the frequencies of the variants, non-schwa variants being more frequent than schwa variants in casual speech.

Connine et al. (2008) further investigated the influence of variant frequency, which they define as “the experienced production frequency of a particular phonological variant relative to an alternative”, on schwa word recognition. Their investigation concerned English words with a schwa in the second syllable (i.e., trisyllabic words, such as corporate).

Based on corpus statistics, they formed two groups of schwa words depending on the non-schwa variants’ frequencies (high versus low deletion-rate words). They then recorded these words and manipulated the duration of the schwa vowel in order to create continua of stimuli with increasing vowel length for each schwa word. In a syllable counting task, they first showed that listeners tend to provide more three-syllable judgments for low deletion-rate words. In addition they found an effect of variant frequency for schwa and non-schwa variants in lexical decision tasks. For schwa variants, however, the influence of variant frequency was weaker. Connine et al. (2008) conclude that the way a word is lexically represented is influenced by the speaker’s experience. According to these authors, this finding can be accounted for in a model where both variants are lexically represented. As for the smaller effect of variant frequency for schwa variants, the authors provide two alternative explanations. According to the first explanation, the processing of schwa variant benefits from richer acoustic information. As a consequence, it may decrease the influence of other

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factors. According to the second explanation, the processing of schwa variants benefits from their consistency with orthography.

To summarize, studies on the recognition of French schwa words show that schwa variants are processed faster than non-schwa variants. This advantage for schwa variants is however restricted to schwa words whose non-schwa variants have a legal onset cluster. On the basis of these results, it is assumed that French schwa words are represented in the lexicon with one representation which contains the schwa, the alternative variant being derived through a process of phonological inference. Similar conclusions are reached for Dutch schwa. Be it for schwa deletion or epenthesis, one abstract representation only per schwa word is assumed, the other variant being derived during the recognition process. On the other hand, studies on English schwa words underline the role of variant frequency in the recognition process. This finding leads some authors to suggest that English schwa words could be represented in the mental lexicon with two abstract representations, one per variant. Whereas no study has yet investigated the role of variant frequency in the recognition of French schwa words, some authors suggest that this variable could play a role. This issue will be further examined in Chapter V. The role of variant frequency will however first be examined in the production of schwa words (Chapter III).

Before we start examining how the language production system handles phonological variation, we need to understand its general features and how they apply to the production of canonical word forms. The following section was designed for this purpose.