Linda Wheeldon

The Locus of Repetition Priming of Spoken Word Production

Naming of a pictured object is substantially facilitated when the name has recently been produced in response to a definition or read aloud. The first experiment shows this to be so when over one hundred trials have intervened, and when the subjects can name the pictures quickly and accurately in the absence of priming. The locus of the effect must be in lexicalization processes subsequent to picture identification and is unlikely to be mediated by recovery of an episodic trace. Two further experiments show that prior production of a homophone of the objects name is not an effective prime, (although slower responses are somewhat facilitated when the homophones are spelled the same). Hence the facilitation observed for repeated production of the same word cannot be associated with the repetition of the phonological form per se. We conclude that the facilitation must be associated with retrieval of the semantic specification or the process of mapping of that specification to its associated phonological representation.

High level processing scope in spoken sentence production.

Five experiments investigate the scope of conceptual and grammatical encoding during spoken sentence production. An online picture description task is employed in which participants generate a variety of sentences in response to an array of moving pictured objects. Experiment 1, demonstrates longer onset latencies for single clause sentences beginning with a complex phrase (e.g. The dog and the kite move above the house) than for matched single clause sentences beginning with a simple phrase (e.g. The dog moves above the kite and the house). This finding suggests that more time is dedicated to the processing of the first phrase of an utterance than the remainder prior to speech onset. Experiments 2 and 3, compare the production of single and double clause sentences. The main effect of Experiment 1 is replicated. However, the data also suggest that some time is dedicated to the processing of elements within the second clause prior to speech onset. In Experiment 4, when participants are allowed to preview pictures prior to movement and timer onset the effect of initial phrase complexity is significantly reduced indicating that the latency effects observed previously primarily reflect lemma access. Finally, Experiment 5 demonstrates that this reduction is greater for nouns within the first phrase than for nouns beyond it. We conclude from these experiments that, prior to speech onset, lemma access is completed for the first phrase of an utterance and that high level processing is initiated but not completed for the remainder of a sentence beyond the first phrase.

Syntactic priming in spoken sentence production – an online study

Six experiments investigate syntactic priming online via a picture description task in which participants produce target sentences whose initial phrase is syntactically similar or dissimilar to that of the prime sentence produced on the previous trial. In the first experiment it is shown that a syntactically related prime sentence speeds onset latencies to a subsequent target sentence by approximately 50 ms relative to a syntactically unrelated prime sentence. In the second experiment, the cost of the process of lemma access is factored out via a picture previewing technique but a priming effect is still obtained demonstrating that the effect is not a product of the priming of lemma access processes. In Experiment 3, the related and unrelated prime trials feature the same picture display but the 50 ms facilitation effect is still observed indicating that the effect does not result from the priming of visual perception of the picture movements. This is further strengthened in Experiment 4 which uses written prime sentences rather than a picture description task on the prime trial and still obtains a facilitation effect. In Experiment 5, the effect disappears when the participants are instructed to name the movements but not the objects depicted in the array and this is interpreted as evidence against the view that the effect results from the conceptualization of the events depicted by the array. In the final experiment, the scope of the syntactic persistence effect is investigated by priming sentences with initial phrases of varying syntactic complexity. Significant priming is only observed for an initial phrase featuring two nouns - a finding consistent with the view that the syntactic persistence effect applies only to the generation of the first phrase of an utterance prior to speech onset. The implications of these results are analyzed in the final discussion section.

Horizontal information flow in spoken sentence production

In 4 experiments the authors used a variant of the picture-word interference paradigm to investigate whether there is a temporal overlap in the activation of words during sentence production and whether there is a flow of semantic and phonological information between them. Experiments 1 and 2 demonstrate that 2 semantically related nouns produce interference effects either when they are in the same or different phrases of a sentence. Experiments 3 and 4 demonstrate that 2 phonologically related nouns produce facilitation effects but only when they are within the same phrase of a sentence. The results argue against strictly serial models of multiple-word access and provide evidence of a flow of semantic and phonological information between words during sentence production.

Phoneme monitoring in internal and external speech

Four experiments examine the time course of phoneme monitoring in internally and externally generated speech. The aim of this research was to replicate and extend previous findings of Wheeldon and Levelt (1995), who required their Dutch participants to monitor their own prearticulatory speech in order to investigate the generation of an abstract phonological code. Experiment 1 required British participants to silently generate English words with a CVCCVC structure and to monitor these words for the four constituent consonants. Similar to the Dutch study, a clear left-to-right monitoring effect was observed and a significant difference was seen between latencies for the consonants separated by the initial vowel and for the consecutive word medial consonants. Internal speech monitoring was also found to speed up across the word. A perception version of the task (Experiment 2) yielded a different pattern of monitoring latencies. In Experiments 3 and 4, all phonemes in the initial CVC syllable of bisyllabic words were monitored in internal and external speech respectively. A significant left-to-right pattern of monitoring latencies was again observed in the internal speech task. However, in the external speech task, monitoring latencies for the vowel and final consonant of the syllable did not differ. The conclusions of Wheeldon and Levelt are discussed and refined in light of the present results.

Inhibitory form priming of spoken word production

Three experiments were designed to examine the effect on picture naming of the prior production of a word related in phonological form. In Experiment 1, the latency to produce Dutch words in response to pictures (e.g., hoed, hat) was longer following the production of a form-related word (e.g., hond, dog) in response to a definition on a preceding trial, than when the preceding definition elicited an unrelated word (e.g., kerk, church). Experiment 2 demonstrated that the inhibitory effect disappears when one unrelated word is produced intervening prime and target productions (e.g., hond-kerk-hoed). The size of the inhibitory effect was not significantly affected by the frequency of the prime words or the target picture names. In Experiment 3, facilitation was observed for word pairs that shared offset segments (e.g., kurk-jurk, cork-dress), whereas inhibition was observed for shared onset segments (e.g., bloed-bloem, blood-flower). However, no priming was observed for prime and target words with shared phonemes but no mismatching segments (e.g., oom-boom, uncle-tree; hex-hexs, fence-witch). These findings are consistent with a process of phoneme competition during phonological encoding.

Phrase structure priming: A short-lived effect

Two experiments investigate the effect of phrase structure priming on sentence production latencies. Repetition priming of sentence initial noun phrase structure has been demonstrated in an on-line picture description task. Experiments 1 and 2 demonstrate this priming effect to be short lived. No priming survives the addition of one intervening unrelated trial. This finding contrasts with the more persistent effects recently demonstrated in off-line picture description tasks. This contrast is attributed to different loci for the two effects.

Phonological Underspecification and Mapping Mechanisms in the Speech Recognition Lexicon.

The problem of recognizing phonological variations in the speech input has triggered numerous treatments in speech processing models. Two areas of current controversy are the possibility of phonological underspecification in the mental lexicon and the nature of the mapping mechanism from the speech signal to the abstract lexical entry. We present data from cross-modal repetition priming experiments in English designed to test the differing predictions of speech recognition models regarding tolerance of phonological mismatch in speech. The results show effects of underspecification, supporting models using underspecified lexical entries (e.g. Lahiri & Marslen-Wilson, 1991; Reetz & Lahiri, 2001) over those using fully specified lexical entries (e.g., McClelland & Elman, 1986). The results also show no effects of context, thus favoring context-independent mapping, such as that in the three-way matching mechanism of the Lahiri and Reetz FUL model ( Lahiri, 1999; Reetz, 1998 and Reetz, 1999; Reetz & Lahiri, 2001) over context-dependent mapping used in phonological inference rules ( Gaskell and Marslen-Wilson, 1996 and Gaskell and Marslen-Wilson, 1998).

Scope of Lexical Access in Spoken Sentence Production: Implications for the Conceptual-Syntactic Interface.

Building on P. H. Allum and L. Wheeldon (2007), the authors conducted 5 experiments to investigate the scope of lexical access during spoken sentence production in Japanese and English. Speakers described pairs of pictured objects, and on critical trials, 1 object was previewed. In Japanese, sentence onset is speeded by the preview of each of the 2 pictures used to elicit a sentence initial coordinated noun phrase (Experiment 1). When the same displays are used to elicit an alternative Japanese listing structure, onset latencies are speeded only by the preview of the first picture to be named (Experiment 2). The findings of Experiment 1 were therefore not the result of stimulus design. Experiment 3 replicated the findings of Experiment 1 in English. Experiments 4 and 5 tested a subject phrase consisting of a noun phrase modified by a prepositional phrase in English and Japanese. In both languages, only preview of the first picture to be named speeds responses, irrespective of whether it occurs in the head phrase (English) or not (Japanese). These results suggest that prior to utterance onset, only access to the nouns for the first phrase to be produced is required, even if this is not the head phrase. The implications for speech production models are discussed.

Lexical availability and grammatical encoding scope during spoken sentence production

Three sentence production experiments investigate the relationship between lexical and structural processing scope. Speakers generated sentences with varying phrase structures in response to visual displays (e.g., The dog and the hat move above the fork and the tree/The dog moves above the hat and the fork and the tree). On half of the trials, one of the pictures in the arrays was previewed. Filler sentences varied preview position and sentence structure from trial to trial. When speakers could not anticipate the position of the previewed picture in the upcoming sentence (Experiment 1), preview benefit for pictures corresponding to the second noun to be produced was limited to pictures that fell within the sentence-initial phrase. When the linear position of the previewed picture was predictable, preview benefits were observed for the second noun to be produced, irrespective of phrase position (Experiment 2). However, no preview benefits were observed for the third noun to be produced (Experiment 3). In contrast, significant effects of initial phrase structure were observed in all experiments, with latencies increasing with initial phrase length. The results are consistent with speakers operating a phrasal scope for structural planning within which the scope of lexical access can vary.