Newly learned spoken words show long-term lexical competition effects

Newly learned spoken words (e.g., “cathedruke”) become fully engaged in the mental lexicon, as measured via lexical competition with their pre-existing phonological neighbours (e.g., “cathedral”), over the course of several hours or days, and this lexical restructuring is associated with sleep (Dumay & Gaskell, 2007). Here, we investigated the longer-term effects of word learning for three sets of novel words learned at different times using phoneme monitoring and repetition tasks. The effects of these exposure sessions on lexical memory were assessed in a battery of tests. Lexical decision latencies to pre-existing neighbouring words showed that lexical competition effects for the novel words remained observable 8 months after initial exposure. Furthermore, the order-of-acquisition of the novel words affected their production speed (but not recognition speed), with an advantage for earlier acquired words. The results suggest that the consolidation of novel words results in a long-term and stable change in the lexical competition process.     

Effects of lexical competition on immediate memory span for spoken words

Current theories and models of the structural organization of verbal short-term memory are primarily based on evidence obtained from manipulations of features inherent in the short-term traces of the presented stimuli, such as phonological similarity. In the present study, we investigated whether properties of the stimuli that are not inherent in the short-term traces of spoken words would affect performance in an immediate memory span task. We studied the lexical neighbourhood properties of the stimulus items, which are based on the structure and organization of words in the mental lexicon. The experiments manipulated lexical competition by varying the phonological neighbourhood structure (i.e., neighbourhood density and neighbourhood frequency) of the words on a test list while controlling for word frequency and intra-set phonological similarity (family size). Immediate memory span for spoken words was measured under repeated and nonrepeated sampling procedures. The results demonstrated that lexical competition only emerged when a nonrepeated sampling procedure was used and the participants had to access new words from their lexicons. These findings were not dependent on individual differences in short-term memory capacity. Additional results showed that the lexical competition effects did not interact with proactive interference. Analyses of error patterns indicated that item-type errors, but not positional errors, were influenced by the lexical attributes of the stimulus items. These results complement and extend previous findings that have argued for separate contributions of long-term knowledge and short-term memory rehearsal processes in immediate verbal serial recall tasks.     

The dynamics of lexical competition during spoken word recognition

The sounds that make up spoken words are heard in a series and must be mapped rapidly onto words in memory because their elements, unlike those of visual words, cannot simultaneously exist or persist in time. Although theories agree that the dynamics of spoken word recognition are important, they differ in how they treat the nature of the competitor set-precisely which words are activated as an auditory word form unfolds in real time. This study used eye tracking to measure the impact over time of word frequency and 2 partially overlapping competitor set definitions: onset density and neighborhood density. Time course measures revealed early and continuous effects of frequency (facilitatory) and on set based similarity (inhibitory). Neighborhood density appears to have early facilitatory effects and late inhibitory effects. The late inhibitory effects are due to differences in the temporal distribution of similarity within neighborhoods. The early facilitatory effects are due to subphonemic cues that inform the listener about word length before the entire word is heard. The results support a new conception of lexical competition neighborhoods in which recognition occurs against a background of activated competitors that changes over time based on fine-grained goodness-of-fit and competition dynamics.     

Grammatical context constrains lexical competition in spoken word recognition

When perceiving spoken language, listeners must match the incoming acoustic phonetic input to lexical representations in memory. Models that quantify this process propose that the input activates multiple lexical representations in parallel and that these activated representations compete for recognition (Weber & Scharenborg, 2012). In two experiments, we assessed how grammatically constraining contexts alter the process of lexical competition. The results suggest that grammatical context constrains the lexical candidates that are activated to grammatically appropriate competitors. Stimulus words with little competition from items of the same grammatical class benefit more from the addition of grammatical context than do words with more within-class competition. The results provide evidence that top-down contextual information is integrated in the early stages of word recognition. We propose adding a grammatical class level of analysis to existing models of word recognition to account for these findings.     

Lexical competition effects in aphasia: deactivation of lexical candidates in spoken word processing

Research has shown that Broca's and Wernicke's aphasic patients show different impairments in auditory lexical processing. The results of an experiment with form-overlapping primes showed an inhibitory effect of form-overlap for control adults and a weak inhibition trend for Broca's aphasic patients, but a facilitatory effect of form-overlap was found for Wernicke's aphasic participants. This suggests that Wernicke's aphasic patients are mainly impaired in suppression of once-activated word candidates and selection of one winning candidate, which may be related to their problems in auditory language comprehension.     

Representation and competition in the perception of spoken words

We present data from four experiments using cross-modal priming to examine the effects of competitor environment on lexical activation during the time course of the perception of a spoken word. The research is conducted from the perspective of a distributed model of speech perception and lexical representation, which focuses on activation at the level of lexical content. In this model, the strength of competition between simultaneously active lexical items depends on the degree of coherence between their distributed semantic and phonological representations. Consistent with this model, interference effects are more complete when the purely semantic aspects of these coactive representations are probed (using semantic priming) than when phonological aspects are probed as well (using repetition priming).     

Phonotactics, neighborhood activation, and lexical access for spoken words.

Probabilistic phonotactics refers to the relative frequencies of segments and sequences of segments in spoken words. Neighborhood density refers to the number of words that are phonologically similar to a given word. Despite a positive correlation between phonotactic probability and neighborhood density, nonsense words with high probability segments and sequences are responded to more quickly than nonsense words with low probability segments and sequences, whereas real words occurring in dense similarity neighborhoods are responded to more slowly than real words occurring in sparse similarity neighborhoods. This contradiction may be resolved by hypothesizing that effects of probabilistic phonotactics have a sublexical focus and that effects of similarity neighborhood density have a lexical focus. The implications of this hypothesis for models of spoken word recognition are discussed.     

Reading spoken words: orthographic effects in auditory priming

Three experiments examined the involvement of orthography in spoken word processing using a task - unimodal auditory priming with offset overlap - taken to reflect activation of prelexical representations. Two types of prime-target relationship were compared; both involved phonological overlap, but only one had a strong orthographic overlap (e.g., dream-gleam vs. scheme-gleam). In Experiment 1, which used lexical decision, phonological overlap facilitated target responses in comparison with an unrelated condition (e.g., stove-gleam). More importantly, facilitation was modulated by degree of orthographic overlap. Experiment 2 employed the same design as Experiment 1, but with a modified procedure aimed at eliciting swifter responses. Again, the phonological priming effect was sensitive to the degree of orthographic overlap between prime and target. Finally, to test whether this orthographic boost was caused by congruency between response type and valence of the prime-target overlap, Experiment 3 used a pseudoword detection task, in which participants responded "yes" to novel words and "no" to known words. Once again phonological priming was observed, with a significant boost in the orthographic overlap condition. These results indicate a surprising level of orthographic involvement in speech perception, and provide clear evidence for mandatory orthographic activation during spoken word recognition.     

Interlingual lexical competition in a spoken sentence context: Evidence from the visual world paradigm

We used the visual world paradigm to examine interlingual lexical competition when Dutch–English bilinguals listened to low-constraining sentences in their nonnative (L2; Experiment 1) and native (L1; Experiment 2) languages. Additionally, we investigated the influence of the degree of cross-lingual phonological similarity. When listening in L2, participants fixated more on competitor pictures of which the onset of the name was phonologically related to the onset of the name of the target in the nontarget language (e.g., fles, “bottle”, given target flower) than on phonologically unrelated distractor pictures. Even when they listened in L1, this effect was also observed when the onsets of the names of the target picture (in L1) and the competitor picture (in L2) were phonologically very similar. These findings provide evidence for interlingual competition during the comprehension of spoken sentences, both in L2 and in L1.     

Processing lexically embedded spoken words

A large number of multisyllabic words contain syllables that are themselves words. Previous research using cross-modal priming and word-spotting tasks suggests that embedded words may be activated when the carrier word is heard. To determine the effects of an embedded word on processing of the larger word, processing times for matched pairs of bisyllabic words were examined to contrast the effects of the presence or absence of embedded words in both 1st- and 2nd-syllable positions. Results from auditory lexical decision and single-word shadowing demonstrate that the presence of an embedded word in the 1st-syllable position speeds processing times for the carrier word. The presence of an embedded word in the 2nd syllable has no demonstrable effect.     

Semantic priming effects from single words in a lexical decision task

The present research examines the semantic priming effects of a centrally presented single prime word to which participants were instructed to either "attend and remember" or "ignore". The prime word was followed by a central probe target on which the participants made a lexical decision task. The main variables manipulated across experiments were prime duration (50 or 100 ms), the presence or absence of a mask following the prime, and the presence (or absence) and type of distractor stimulus (random set of consonants or pseudowords) on the probe display. There was a consistent interaction between the instructions and the semantic priming effects. Relative to the "attend and remember" instruction, an "ignore" instruction produced reduced positive priming from single primes presented for 100 ms, irrespective of the presence or absence of a prime mask, and regardless of whether the probe target was presented with or without distractors. Additionally, reliable negative priming was found from ignored primes presented for briefer durations (50 ms) and immediately followed by a mask. Methodological and theoretical implications of the present findings for the extant negative priming literature are discussed.     

Similarity neighborhoods of spoken two-syllable words: retroactive effects on multiple activation

This research examines the recognition of two-syllable spoken words and the means by which the auditory word recognition process deals with ambiguous stimulus information. The experiments reported here investigate the influence of individual syllables within two-syllable words on the recognition of each other. Specifically, perceptual identification of two-syllable words comprised of two monosyllabic words (spondees) was examined. Individual syllables within a spondee were characterized as either "easy" or "hard" depending on the syllable's neighborhood characteristics; an easy syllable was defined as a high-frequency word in a sparse neighborhood of low-frequency words, and a hard syllable as a low-frequency word in a high-density, high-frequency neighborhood. In Experiment 1, stimuli were created by splicing together recordings of the component syllables of the spondee, thus equating for syllable stress. Additional experiments tested the perceptual identification of naturally produced spondees, spliced nonwords, and monosyllables alone. Neighborhood structure had a strong effect on identification in all experiments. In addition, identification performance for spondees with a hard-easy syllable pattern was higher than for spondees with an easy-hard syllable pattern, indicating a primarily retroactive pattern of influence in spoken word recognition. Results strongly suggest that word recognition involves multiple activation and delayed commitment, thus ensuring accurate and efficient recognition.     

Six-month-old infants' preference for lexical words

Previous work has shown that newborn infants categorically discriminate the fundamental syntactic category distinction between lexical and grammatical words. In this article, we show that by the age of 6 months, infants prefer to listen to lexical over grammatical words. In Experiment 1, infants were habituated to a list of either lexical or grammatical words, and then tested on new lists of words from the same and the contrasting categories. The infants showed recovery to lexical words after habituation to grammatical words but not vice versa. This asymmetry indicates a possible preference for lexical words. In Experiments 2 and 3, preference was assessed directly by presenting infants with alternating trials of lexical and grammatical words, in the central-fixation preference procedure. The infants looked significantly longer during lexical-word than grammatical-word trials. These results show that by 6 months, infants attend preferentially to lexical words. The implications of this emerging attentional preference for subsequent language acquisition are discussed.     

Domain effects in lexical development: learning words for foods and toys

We investigated 3-year-olds’ and adults’ use of domain cues in learning words for solid and nonsolid material entities. In Experiments 1 and 2, participants heard a novel neutral noun (e.g., “my X”) for a standard solid or nonsolid entity described as either a toy or a food. They then were asked to extend the word to one of two other entities. Both options matched the standard in solidity; but one differed from it in an object-relevant property (shape) and the other in a substance-relevant property (color, texture, or smell). Both children and adults were more likely to select the same-shaped entity if the standard was (1) solid than if it was nonsolid, and (2) described as a toy than if it was described as a food. Their interpretations of novel words for material entities were thus affected not only by perceptual information (about solidity) but also by conceptual information (about domain). In Experiment 3, the novel noun was presented in a syntactic context that suggested the solid entity should be interpreted as an object (e.g., “an X”) and that the nonsolid entity should be interpreted as a substance (e.g., “some X”). For adults, these changes largely eliminated the effect of the entity’s domain (toy, food) on interpretation. We interpret these findings in terms of the proposal that domain cues, like solidity cues, furnish information about whether an entity’s structure should be thought of as arbitrary or nonarbitrary and, hence, about whether a word should be interpreted as naming an object or a substance construal.     

Bedding down new words: Sleep promotes the emergence of lexical competition in visual word recognition

Lexical competition processes are widely viewed as the hallmark of visual word recognition, but little is known about the factors that promote their emergence. This study examined for the first time whether sleep may play a role in inducing these effects. A group of 27 participants learned novel written words, such as banara, at 8 am and were tested on their learning at 8 pm the same day (AM group), while 29 participants learned the words at 8 pm and were tested at 8 am the following day (PM group). Both groups were retested after 24 hours. Using a semantic categorization task, we showed that lexical competition effects, as indexed by slowed responses to existing neighbor words such as banana, emerged 12 h later in the PM group who had slept after learning but not in the AM group. After 24 h the competition effects were evident in both groups. These findings have important implications for theories of orthographic learning and broader neurobiological models of memory consolidation.     

Tracking recognition of spoken words by tracking looks to printed words

Eye movements of Dutch participants were tracked as they looked at arrays of four words on a computer screen and followed spoken instructions (e.g., “Klik op het woord buffel”: Click on the word buffalo). The arrays included the target (e.g., buffel), a phonological competitor (e.g., buffer, buffer), and two unrelated distractors. Targets were monosyllabic or bisyllabic, and competitors mismatched targets only on either their onset or offset phoneme and only by one distinctive feature. Participants looked at competitors more than at distractors, but this effect was much stronger for offset-mismatch than onset-mismatch competitors. Fixations to competitors started to decrease as soon as phonetic evidence disfavouring those competitors could influence behaviour. These results confirm that listeners continuously update their interpretation of words as the evidence in the speech signal unfolds and hence establish the viability of the methodology of using eye movements to arrays of printed words to track spoken-word recognition.     

Phonological priming reflects lexical competition

A phonological relationship between a prime and a target produces facilitation when one or two initial phonemes are shared (low-similarity facilitation) but produces interference when more phonemes are shared (high-similarity interference; Slowiaczek & Hamburger, 1992). Although low-similarity facilitation appears to be a strategic effect (Goldinger, Luce, Pisoni, & Marcario, 1992), this result cannot generalize to high-similarity interference because the two effects are dissociated (Slowiaczek & Hamburger, 1992). In the present study, strategic processing in high-similarity interference was investigated. The phonological relatedness proportion (PRP) and the prime-target interstimulus interval (ISI) were varied in a shadowing experiment. Low-similarity facilitation was found only with a high PRP and long ISI, but high-similarity interference was found regardless of PRP and ISI. These results suggest that strategies influence low-similarity facilitation, but high-similarity interference reflects automatic processing.     

Initial phonemes are detected faster in spoken words than in spoken nonwords

In two experiments, subjects monitored sequences of spoken consonant-vowel-consonant words and nonwords for a specified initial phoneme. In Experiment I, the target-carrying monosyllables were embedded in sequences in which the monosyllables were all words or all nonwords. The possible contextual bias of Experiment I was minimized in Experiment II through a random mixing of target-carrying words and nonwords with foil words and nonwords. Target-carrying words were distinguished in both experiments from target-carrying nonwords only in the final consonant, e.g., /bit/ vs. /bip/. In both experiments, subjects detected the specified consonant /b/ significantly faster when it began a word than when it began a nonword. One interpretation of this result is that in speech perception lexical information is accessed before phonological information. This interpretation was questioned and preference was given to the view that the result reflected processes subsequent to perception: words become available to awareness faster than nonwords and therefore provide a basis for differential responding that much sooner.     

Rhyme decisions to spoken words and nonwords

Lexical effects in auditory rhyme-decision performance were examined in three experiments. Experiment 1 showed reliable lexical involvement: rhyme-monitoring responses to words were faster than rhyme-monitoring responses to nonwords; and decisions were faster in response to high-frequency as opposed to low-frequency words. Experiments 2 and 3 tested for lexical influences in the rejection of three types of nonrhyming item: words, nonwords with rhyming lexical neighbors (e.g.,jop after the cuerob), and nonwords with no rhyming lexical neighbor (e.g.,vop afterrob). Words were rejected more rapidly than nonwords, and there were reliable differences in the speed and accuracy of rejection of the two types of nonword. The advantage for words over nonwords was replicated for positive rhyme decisions. However, there were no differences in the speed of acceptance, as rhymes, of the two types of nonword. The implications of these results for interactive and autonomous models of spoken word recognition are discussed. It is concluded that the differences in rejection of nonrhyming nonwords are due to the operation of a guessing strategy.