Lexically guided retuning of letter perception

Participants made visual lexical decisions to upper-case words and nonwords, and then categorized an ambiguous N-H letter continuum. The lexical decision phase included different exposure conditions: Some participants saw an ambiguous letter "?", midway between N and H, in N-biased lexical contexts (e.g., REIG?), plus words with unambiguous H (e.g., WEIGH); others saw the reverse (e.g., WEIG?, REIGN). The first group categorized more of the test continuum as N than did the second group. Control groups, who saw "?" in nonword contexts (e.g., SMIG?), plus either of the unambiguous word sets (e.g., WEIGH or REIGN), showed no such subsequent effects. Perceptual learning about ambiguous letters therefore appears to be based on lexical knowledge, just as in an analogous speech experiment (Norris, McQueen, & Cutler, 2003) which showed similar lexical influence in learning about ambiguous phonemes. We argue that lexically guided learning is an efficient general strategy available for exploitation by different specific perceptual tasks.     

Perceptual learning in speech

This study demonstrates that listeners use lexical knowledge in perceptual learning of speech sounds. Dutch listeners first made lexical decisions on Dutch words and nonwords. The final fricative of 20 critical words had been replaced by an ambiguous sound, between [f] and [s]. One group of listeners heard ambiguous [f]-final words (e.g., [WItlo?], from witlof, chicory) and unambiguous [s]-final words (e.g., naaldbos, pine forest). Another group heard the reverse (e.g., ambiguous [na:ldbo?], unambiguous witlof). Listeners who had heard [?] in [f]-final words were subsequently more likely to categorize ambiguous sounds on an [f]-[s] continuum as [f] than those who heard [?] in [s]-final words. Control conditions ruled out alternative explanations based on selective adaptation and contrast. Lexical information can thus be used to train categorization of speech. This use of lexical information differs from the on-line lexical feedback embodied in interactive models of speech perception. In contrast to on-line feedback, lexical feedback for learning is of benefit to spoken word recognition (e.g., in adapting to a newly encountered dialect).     

Turning an advantage into a disadvantage: Ambiguity effects in lexical decision versus reading tasks

When performing a lexical decision task, participants can correctly categorize letter strings as words faster if they have multiple meanings (i.e., ambiguous words) than if they have one meaning (i.e., unambiguous words). In contrast, when reading connected text, participants tend to fixate longer on ambiguous words than on unambiguous words. Why are ambiguous words at an advantage in one word recognition task, and at a disadvantage in another? These disparate results can be reconciled if it is assumed that ambiguous words are relatively fast to reach a semantic-blend state sufficient for supporting lexical decisions, but then slow to escape the blend when the task requires a specific meaning be retrieved. We report several experiments that support this possibility.     

Event-related potential and reaction time evidence for inhibition between alternative meanings of ambiguous words

We investigated the effects of two primes that converged onto the same semantic target representation (e.g., LION-STRIPES-TIGER) or diverged onto different semantic target representations (e.g., KIDNEY-PIANO-ORGAN). Balota and Paul (1996) showed that the RT effects of two related primes in naming and lexical decision are additive, both for unambiguous and ambiguous words. Only in a relatedness judgment task ambiguous words showed underadditivity, whereas unambiguous words again showed additivity. This underadditivity was interpreted to reflect inhibition of alternative meanings of ambiguous words. In this article we tested whether inhibition occurs for N400, assumed to index postlexical integration. In lexical decision, we found additive N400 and RT effects for unambiguous and for ambiguous words. In a relatedness judgment task we observed differences between measures: (1) for unambiguous words overadditivity for N400 vs. additivity for RT; (2) although, for ambiguous words underadditivity occurred for N400 and RT, the effects were different. For RT, the alternative meaning was only less available, whereas for N400 the alternative meaning appeared completely unavailable. Our results have implications for our understanding of inhibitory processes in the processing of ambiguous words and for the functional significance of N400.     

Semantic ambiguity and the failure of inhibition hypothesis as an explanation for reading errors in deep dyslexia

We report evidence for dissociation between explicit and implicit access to word representations in a deep dyslexic patient (JO). JO read aloud a series of ambiguous (e.g., bank) and unambiguous (e.g., food) words and performed a lexical decision task using these same items. When required to explicitly access the items (i.e., naming), JO showed relative impairment for ambiguous compared with unambiguous words. In contrast, the same stimuli produced an advantage for ambiguous words in lexical decision. The results are discussed within a framework of deep dyslexia that considers errors in production to arise through a failure to inhibit spuriously activated candidate representations.     

Communicative Context Affects Use of Referential Prosody

The current study assessed the extent to which the use of referential prosody varies with communicative demand. Speaker–listener dyads completed a referential communication task during which speakers attempted to indicate one of two color swatches (one bright, one dark) to listeners. Speakers' bright sentences were reliably higher pitched than dark sentences for ambiguous (e.g., bright red versus dark red) but not unambiguous (e.g., bright red versus dark purple) trials, suggesting that speakers produced meaningful acoustic cues to brightness when the accompanying linguistic content was underspecified (e.g., “Can you get the red one?”). Listening partners reliably chose the correct corresponding swatch for ambiguous trials when lexical information was insufficient to identify the target, suggesting that listeners recruited prosody to resolve lexical ambiguity. Prosody can thus be conceptualized as a type of vocal gesture that can be recruited to resolve referential ambiguity when there is communicative demand to do so.     

Naming solids and nonsolids: Children's default construals

Four experiments used a free-naming task to examine children's and adults' default construals of solids and nonsolids. In Experiment 1,4-year-old children viewed entities presented in familiar geometric shapes (e.g., square, triangle), without touching them. One half saw solids (e.g., a square made of wood); the other half saw nonsol ids matched carefully in shape (e.g., a square with the same dimensions but made of peanut butter). To tap their default construals, children were simply asked, “What is that?” Answers varied sharply with the type of stimulus. If the entity was solid, children tended to provide an individual-related word (e.g., “a square”), even if they also knew a substance-related word (e.g., “wood”). But if the stimulus was nonsolid, children tended to give a substance-related word (e.g., “peanut butter”), even if they also knew an individual-related word (e.g., “a square”). These words were usually common nouns produced in appropriate sentential contexts, suggesting that 4-year-olds represented the words as naming kinds. The same pattern of results obtained in Experiments 2 and 3, which were modified replications of Experiment 1. The results of Experiment 4 replicated the main findings of Experiment 1 using adults as participants. The studies suggest that, as a default, 4-year-olds conceptualize solids and nonsolids in (a) fundamentally distinct, (b) kind-based (rather than perceptual property-based), and (c) adult-like ways.     

语法语境下汉语名动分离的ERP研究

运用ERP技术,从语法角度,通过词语搭配判断任务,考察汉语名词和动词加工的脑神经机制。实验结果显示,在适合的语法语境中,名词、动词和动名兼类词所诱发出ERP差异主要反应在P200、N400和P600三个ERP成分上。在正确的语境中,名词诱发出更大的P200,而动词则诱发出比名词更大的N400和减小的P600;当动名兼类词分别用作名词和动词时,虽然二者的N400没有显著差异,但前者诱发出一个增大的P600。根据实验结果认为：汉语名词和动词具有不同的神经表征和加工机制,名词和动词的语法功能在汉语名动分离中起了重要的作用     

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.     

Context effects in word recognition: evidence for early interactive processing

This study investigated whether a prior context influenced lexical access as indexed by participants' electrophysiological response in the N1 from 132 to 192 ms poststimulus. Ambiguous, high-frequency (HF), and low-frequency (LF) words were presented in neutral and biasing contexts. Event-related potentials (ERPs) for ambiguous words were compared with those for unambiguous HF (word form) and LF (word meaning) control words. Word frequency effects in the N1 extended previous ERP findings. A marginal effect of context for LF words provided electrophysiological support for the context-by-frequency interaction shown in reaction time paradigms. In neutral context, responses to ambiguous words were comparable to responses to HF words, and in biasing context (where context instantiated the subordinate sense), responses to ambiguous words were comparable to responses to LF words. The results establish temporal parameters for the early operation of context in lexical access. These constraints are more consistent with an interactive than a modular account.     

Sentence context effects on lexically ambiguous words: Evidence for a postaccess inhibition process

Two experiments were conducted to investigate the process involved in selecting the contextually appropriate meaning of a homograph. Both experiments employed a grammaticality decision task. In Experiment 1, the primary (more frequent) and secondary (less frequent) meanings of homographs were used as the target items requiring a “yes” decision. The results indicated that the effect of relative frequency of these meanings of homographs was reduced when the target word was preceded either by a semantically congruous or anomalous sentence context relative to when it was preceded by the grammatical morpheme “the” or “to.” Experiment 2 indicated that “no” decisions were consistently slower for syntactically unambiguous, but semantically ambiguous words (e.g., ORGAN, FEET) than for syntactically and semantically unambiguous words (e.g., CENT, LEND), irrespective of the type of preceding context. The results, taken as a whole, are best interpreted within the postaccess inhibition model of sentence-context effects suggested by Forster (1981).     

Lexical and sublexical processes in the perception of transposed-letter anagrams

Evidence from priming and lexical decision tasks suggests that nonwords created by transposing adjacent letter pairs (TL nonwords) are very effective in activating lexical representations of their base words, because the process of orthographic matching tolerates minor changes in letter position. However, this account disregards the possible role of sublexical processing in reading. TL nonwords are perceptually ambiguous, with lexical and sublexical processing giving rise to conflicting interpretations. The consequences of this ambiguity were investigated in a lexical decision experiment with primes that were either high or low bigram frequency TL versions of target words. Priming effects were much larger for low BF primes (e.g., pucnh-PUNCH) than for high BF primes (e.g., panit-PAINT). This finding is interpreted as evidence that lexical activation can be inhibited by competing output resulting from sublexical processing of TL letter string. We conclude that phonological processing is an important determinant of responses to TL stimuli, and we consider how this interpretation might be accommodated within the dual-route cascaded (DRC) model of word recognition.     

Possible words and fixed stress in the segmentation of Slovak speech

The possible-word constraint (PWC; Norris, McQueen, Cutler, & Butterfield, 1997) has been proposed as a language-universal segmentation principle: Lexical candidates are disfavoured if the resulting segmentation of continuous speech leads to vowelless residues in the input—for example, single consonants. Three word-spotting experiments investigated segmentation in Slovak, a language with single-consonant words and fixed stress. In Experiment 1, Slovak listeners detected real words such as ruka “hand” embedded in prepositional-consonant contexts (e.g., /gruka/) faster than those in nonprepositional-consonant contexts (e.g., /truka/) and slowest in syllable contexts (e.g., /dugruka/). The second experiment controlled for effects of stress. Responses were still fastest in prepositional-consonant contexts, but were now slowest in nonprepositional-consonant contexts. In Experiment 3, the lexical and syllabic status of the contexts was manipulated. Responses were again slowest in nonprepositional-consonant contexts but equally fast in prepositional-consonant, prepositional-vowel, and nonprepositional-vowel contexts. These results suggest that Slovak listeners use fixed stress and the PWC to segment speech, but that single consonants that can be words have a special status in Slovak segmentation. Knowledge about what constitutes a phonologically acceptable word in a given language therefore determines whether vowelless stretches of speech are or are not treated as acceptable parts of the lexical parse.     

The specificity of perceptual learning in speech processing

We conducted four experiments to investigate the specificity of perceptual adjustments made to unusual speech sounds. Dutch listeners heard a female talker produce an ambiguous fricative [?] (between [f] and [s]) in [f]- or [s]-biased lexical contexts. Listeners with [f]-biased exposure (e.g., [witlo?]; from witlof, "chicory"; witlos is meaningless) subsequently categorized more sounds on an [epsilonf]-[epsilons] continuum as [f] than did listeners with [s]-biased exposure. This occurred when the continuum was based on the exposure talker's speech (Experiment 1), and when the same test fricatives appeared after vowels spoken by novel female and male talkers (Experiments 1 and 2). When the continuum was made entirely from a novel talker's speech, there was no exposure effect (Experiment 3) unless fricatives from that talker had been spliced into the exposure talker's speech during exposure (Experiment 4). We conclude that perceptual learning about idiosyncratic speech is applied at a segmental level and is, under these exposure conditions, talker specific.     

Lexical and sublexical processes in the perception of transposed-letter anagrams

Evidence from priming and lexical decision tasks suggests that nonwords created by transposing adjacent letter pairs (TL nonwords) are very effective in activating lexical representations of their base words, because the process of orthographic matching tolerates minor changes in letter position. However, this account disregards the possible role of sublexical processing in reading. TL nonwords are perceptually ambiguous, with lexical and sublexical processing giving rise to conflicting interpretations. The consequences of this ambiguity were investigated in a lexical decision experiment with primes that were either high or low bigram frequency TL versions of target words. Priming effects were much larger for low BF primes (e.g., pucnh–PUNCH) than for high BF primes (e.g., panit–PAINT). This finding is interpreted as evidence that lexical activation can be inhibited by competing output resulting from sublexical processing of TL letter string. We conclude that phonological processing is an important determinant of responses to TL stimuli, and we consider how this interpretation might be accommodated within the dual-route cascaded (DRC) model of word recognition.     

The organization of words and environmental sounds in the second year: Behavioral and electrophysiological evidence

The majority of research examining early auditory‐semantic processing and organization is based on studies of meaningful relations between words and referents. However, a thorough investigation into the fundamental relation between acoustic signals and meaning requires an understanding of how meaning is associated with both lexical and non‐lexical sounds. Indeed, it is unknown how meaningful auditory information that is not lexical (e.g., environmental sounds) is processed and organized in the young brain. To capture the structure of semantic organization for words and environmental sounds, we record event‐related potentials as 20‐month‐olds view images of common nouns (e.g., dog) while hearing words or environmental sounds that match the picture (e.g., “dog” or barking), that are within‐category violations (e.g., “cat” or meowing), or that are between‐category violations (e.g., “pen” or scribbling). Results show both words and environmental sounds exhibit larger negative amplitudes to between‐category violations relative to matches. Unlike words, which show a greater negative response early and consistently to within‐category violations, such an effect for environmental sounds occurs late in semantic processing. Thus, as in adults, the young brain represents semantic relations between words and between environmental sounds, though it more readily differentiates semantically similar words compared to environmental sounds.     

Non-Selective Lexical Access in Late Arabic–English Bilinguals: Evidence from Gating

Previous research suggests that late bilinguals who speak typologically distant languages are the least likely to show evidence of non-selective lexical access processes. This study puts this claim to test by using the gating task to determine whether words beginning with speech sounds that are phonetically similar in Arabic and English (e.g., [b,d,m,n]) give rise to selective or non-selective lexical access processes in late Arabic–English bilinguals. The results show that an acoustic-phonetic input (e.g., [bæ]) that is consistent with words in Arabic (e.g., [bædrun] “moon”) and English (e.g., [bæd] “bad”) activates lexical representations in both languages of the bilingual. This non-selective activation holds equally well for mixed lists with words from both Arabic and English and blocked lists consisting only of Arabic or English words. These results suggest that non-selective lexical access processes are the default mechanism even in late bilinguals of typologically distant languages.     

Generalization in perceptual learning for speech

Lexical context strongly influences listeners’ identification of ambiguous sounds. For example, a sound midway between /f/ and /s/ is reported as /f/ in “sheri_’” but as /s/ in “Pari_.” Norris, McQueen, and Cutler (2003) have demonstrated that after hearing such lexically determined phonemes, listeners expand their phonemic categories to include more ambiguous tokens than before. We tested whether listeners adjust their phonemic categories for a specific speaker: Do listeners learn a particular speaker’s “accent”? Similarly, we examined whether perceptual learning is specific to the particular ambiguous phonemes that listeners hear, or whether the adjustments generalize to related sounds. Participants heard ambiguous /d/ or /t/ phonemes during a lexical decision task. They then categorized sounds on /d/-/t/ and /b/-/p/ continua, either in the same voice that they had heard for lexical decision, or in a different voice. Perceptual learning generalized across both speaker and test continua: Changes in perceptual representations are robust and broadly tuned.     

The Development of Strategic Processing of Ambiguous Words: Riddles Versus Neutral Context

Children in Grades 4 and 6 read isolated target words following the auditory presentation of an ambiguous word (e.g., deck). The ambiguous word occurred as the last word in either a neutral sentence (e.g., “There is the deck”) or as the last word in a riddle (“Why couldn't anybody play poker on the ark? Because Noah sat on the deck). Related target words were consistent with either the dominant meaning (e.g., porch) or the subordinate meaning (cards) of the ambiguous word. In the neutral context, Grade 4 children showed equivalent facilitation for dominant and subordinate targets relative to unrelated target words; Grade 6 children showed facilitation only for the dominant targets. In the riddle context, both groups of children showed equivalent facilitation for the two types of related targets. The neutral context results supported the hypothesis that the two bases of context effects—automatic lexical access and selective access—develop at different rates (Simpson &; Foster, 1986). The results obtained from the riddles suggest that the selective process is strategic (Ceci, 1989).     

Loci of phonological effects in the lexical access of words written in a shallow orthography

Summary Three experiments are reported that extend previous observations on the slowing of lexical decisions by phonologically ambiguous forms of Serbo-Croatian words relative to the phonologically unambiguous forms of the same words. The phonological ambiguity arises from the presence of letters whose phoneme interpretation differs between the two Serbo-Croatian alphabets, the Roman and the Cyrillic. In the first experiment, target words were preceded by asterisks or by context words that were associatively related and alphabetically matched to the targets. The effect of word contexts (i.e., priming) was greater for phonologically ambiguous than for phonologically unambiguous targets. The second experiment manipulated the alphabetic match of context word and target word. The effect of this manipulation was limited to phonologically ambiguous words. The third experiment reproduced the details of the first with the addition of visual degradation of the target stimuli on half of the trials. The results of the first experiment were replicated but no interaction between context and visual degradation was observed. The discussion focused on phonologically mediated access of Serbo-Croatian words. A model was proposed in which phonological codes are assembled prelexically according to weighted grapheme-phoneme correspondence rules.