Same items, different order: effects of temporal variability on infant categorization

How does variability between members of a category influence infants’ category learning? We explore the impact of the order in which different items are sampled on category formation. Two groups of 10-months-olds were presented with a series of exemplars to be organized into a single category. In a low distance group, the order of presentation minimized the perceptual distance between consecutive exemplars. In a high distance group, the order of presentation maximized the distance between successive exemplars. At test, only infants in the High Distance condition reliably discriminated between the category prototype and an atypical exemplar. Hence, the order in which infants learnt about the exemplars impacted their categorization performance. Our findings demonstrate the importance of moment-to-moment variations in similarity during infants’ category learning.     

The role of grammatical class on word recognition

The double dissociation between noun and verb processing, well documented in the neuropsychological literature, has not been supported in imaging studies. Recent imaging studies, in fact, suggest that once confounding with semantics is eliminated, grammatical class effects only emerge as a consequence of building frames. Here we assess this hypothesis behaviorally in two visual word recognition experiments. In Experiment 1, participants made lexical decisions on verb targets. We manipulated the grammatical class of the prime words (either nouns or verbs and always introduced in a minimal phrasal context, i.e., “the + N” or “to + V”), and their semantic similarity to a target (related vs. unrelated). We found reliable effects of grammatical class, and no interaction with semantic similarity. Experiment 2 further explored this grammatical class effect, using verb targets preceded by semantically unrelated verb vs. noun primes. In one condition, prime words were presented as bare words; in the other, they were presented in the minimal phrasal context used in Experiment 1. Grammatical class effects only arose in the latter but not in the former condition thus providing evidence that word recognition does not recruit grammatical class information unless it is provided to the system.     

Vowel categorization during word recognition in bilingual toddlers

Toddlers’ and preschoolers’ knowledge of the phonological forms of words was tested in Spanish-learning, Catalan-learning, and bilingual children. These populations are of particular interest because of differences in the Spanish and Catalan vowel systems: Catalan has two vowels in a phonetic region where Spanish has only one. The proximity of the Spanish vowel to the Catalan ones might pose special learning problems. Children were shown picture pairs; the target picture’s name was spoken correctly, or a vowel in the target word was altered. Altered vowels either contrasted with the usual vowel in Spanish and Catalan, or only in Catalan. Children’s looking to the target picture was used as a measure of word recognition. Monolinguals’ word recognition was hindered by within-language, but not non-native, vowel changes. Surprisingly, bilingual toddlers did not show sensitivity to changes in vowels contrastive only in Catalan. Among preschoolers, Catalan-dominant bilinguals but not Spanish-dominant bilinguals revealed mispronunciation sensitivity for the Catalan-only contrast. These studies reveal monolingual children’s robust knowledge of native-language vowel categories in words, and show that bilingual children whose two languages contain phonetically overlapping vowel categories may not treat those categories as separate in language comprehension.     

Using variability to guide dimensional weighting: associative mechanisms in early word learning

At 14 months, children appear to struggle to apply their fairly well-developed speech perception abilities to learning similar sounding words (e.g., bih/dih; Stager & Werker, 1997). However, variability in nonphonetic aspects of the training stimuli seems to aid word learning at this age. Extant theories of early word learning cannot account for this benefit of variability. We offer a simple explanation for this range of effects based on associative learning. Simulations suggest that if infants encode both noncontrastive information (e.g., cues to speaker voice) and meaningful linguistic cues (e.g., place of articulation or voicing), then associative learning mechanisms predict these variability effects in early word learning. Crucially, this means that despite the importance of task variables in predicting performance, this body of work shows that phonological categories are still developing at this age, and that the structure of noninformative cues has critical influences on word learning abilities.     

No strong evidence for lateralisation of word reading and face recognition deficits following posterior brain injury

Face recognition and word reading are thought to be mediated by relatively independent cognitive systems lateralised to the right and left hemispheres, respectively. In this case, we should expect a higher incidence of face recognition problems in patients with right hemisphere injury and a higher incidence of reading problems in patients with left hemisphere injury. We tested this hypothesis in a group of 31 patients with unilateral right or left hemisphere infarcts in the territory of the posterior cerebral arteries. In most domains tested (e.g., visual attention, object recognition, visuo-construction, motion perception), we found that both patient groups performed significantly worse than a matched control group. In particular, we found a significant number of face recognition deficits in patients with left hemisphere injury and a significant number of patients with word reading deficits following right hemisphere injury. This suggests that face recognition and word reading may be mediated by more bilaterally distributed neural systems than is commonly assumed.     

Examining the effects of variation in emotional tone of voice on spoken word recognition

Emotional tone of voice (ETV) is essential for optimal verbal communication. Research has found that the impact of variation in nonlinguistic features of speech on spoken word recognition differs according to a time course. In the current study, we investigated whether intratalker variation in ETV follows the same time course in two long-term repetition priming experiments. We found that intratalker variability in ETVs affected reaction times to spoken words only when processing was relatively slow and difficult, not when processing was relatively fast and easy. These results provide evidence for the use of both abstract and episodic lexical representations for processing within-talker variability in ETV, depending on the time course of spoken word recognition.     

Code-switching effects in bilingual word recognition: a masked priming study with event-related potentials

Two experiments tested language switching effects with bilingual participants in a priming paradigm with masked primes (duration of 50 ms in Experiment 1 and 100 ms in Experiment 2). Participants had to monitor target words for animal names, and ERPs were recorded to critical (non-animal) words in L1 and L2 primed by unrelated words from the same or the other language. Both experiments revealed language priming (switching) effects that depended on target language. For target words in L1, most of the language switch effect appeared in the N400 ERP component, with L2 primes generating a more negative going wave than L1 primes. For L2 target words, on the other hand, the effects of a language switch appeared mainly in an earlier ERP component (N250) peaking at approximately 250 ms post-target onset, and showing greater negativity following an L1 prime than an L2 prime. This is the first evidence for fast-acting language-switching effects occurring in the absence of overt task switching.     

The role of novelty in early word learning

What mechanism implements the mutual exclusivity bias to map novel labels to objects without names? Prominent theoretical accounts of mutual exclusivity (e.g., Markman, 1989, 1990 ) propose that infants are guided by their knowledge of object names. However, the mutual exclusivity constraint could be implemented via monitoring of object novelty (see Merriman, Marazita, & Jarvis, 1995 ). We sought to discriminate between these contrasting explanations across two preferential looking experiments with 22‐month‐olds. In Experiment 1, infants viewed three objects: one name‐known, two name‐unknown. Of the two name‐unknown objects, one was novel, and the other had been previously familiarized. The infants responded to hearing a novel label by increasing attention only to the novel, name‐unknown object. In a second experiment in which the name‐known object was absent, a novel label increased infants’ attention to a novel object beyond baseline preference for novelty. The experiments provide clear evidence for a novelty‐based mechanism. However, differences in the time course of disambiguation across experiments suggest that novelty processing may be influenced by contextual factors.     

Influences of spoken word planning on speech recognition

In 4 chronometric experiments, influences of spoken word planning on speech recognition were examined. Participants were shown pictures while hearing a tone or a spoken word presented shortly after picture onset. When a spoken word was presented, participants indicated whether it contained a prespecified phoneme. When the tone was presented, they indicated whether the picture name contained the phoneme (Experiment 1) or they named the picture (Experiment 2). Phoneme monitoring latencies for the spoken words were shorter when the picture name contained the prespecified phoneme compared with when it did not. Priming of phoneme monitoring was also obtained when the phoneme was part of spoken nonwords (Experiment 3). However, no priming of phoneme monitoring was obtained when the pictures required no response in the experiment, regardless of monitoring latency (Experiment 4). These results provide evidence that an internal phonological pathway runs from spoken word planning to speech recognition and that active phonological encoding is a precondition for engaging the pathway.     

Age-of-acquisition effects in visual word recognition: evidence from expert vocabularies

Three experiments assessed the contributions of age-of-acquisition (AoA) and frequency to visual word recognition. Three databases were created from electronic journals in chemistry, psychology and geology in order to identify technical words that are extremely frequent in each discipline but acquired late in life. In Experiment 1, psychologists and chemists showed an advantage in lexical decision for late-acquired/high-frequency words (e.g. a psychologist responding to cognition) over late-acquired/low-frequency words (e.g. a chemist responding to cognition), revealing a frequency effect when words are perfectly matched. However, contrary to theories that exclude AoA as a factor, performance was similar for the late-acquired/high-frequency and early-acquired/low-frequency words (e.g. dragon) even though their cumulative frequencies differed by more than an order of magnitude. This last finding was replicated with geologists using geology words matched with early-acquired words in terms of concreteness (Experiment 2). Most interestingly, Experiment 3 yielded the same pattern of results in naming while controlling for imageability, a finding that is particularly problematic for parallel distributed processing models of reading.     

Genetic and environmental influences on individual differences in printed word recognition

The genetic and environmental etiologies of individual differences in printed word recognition and related skills were explored in 440 identical and fraternal twin pairs between 8 and 18 years of age. A theoretically driven measurement model identified five latent variables: IQ, phoneme awareness, word recognition, phonological decoding, and orthographic coding. Cholesky decomposition models on these five latent constructs revealed the existence of both common and independent genetic effects, as well as non-shared environmental influences. There was evidence for moderate genetic influences common between IQ, phoneme awareness, and word-reading skills, and for stronger IQ-independent genetic influences that were common between phoneme awareness and word-reading skills, particularly phonological decoding. Phonological and orthographic coding skills in word recognition had both significant common and significant independent genetic influences, with implications for "dual-route" and "connectionist" reading models, subtypes of reading disabilities, and the remediation of reading disabilities.     

Interhemispheric cooperation and non-cooperation during word recognition: evidence for callosal transfer dysfunction in dyslexic adults

Participants report briefly-presented words more accurately when two copies are presented, one in the left visual field (LVF) and another in the right visual field (RVF), than when only a single copy is presented. This effect is known as the 'redundant bilateral advantage' and has been interpreted as evidence for interhemispheric cooperation. We investigated the redundant bilateral advantage in dyslexic adults and matched controls as a means of assessing communication between the hemispheres in dyslexia. Consistent with previous research, normal adult readers in Experiment 1 showed significantly higher accuracy on a word report task when identical word stimuli were presented bilaterally, compared to unilateral RVF or LVF presentation. Dyslexics, however, did not show the bilateral advantage. In Experiment 2, words were presented above fixation, below fixation or in both positions. In this experiment both dyslexics and controls benefited from the redundant presentation. Experiment 3 combined whole words in one visual field with word fragments in the other visual field (the initial and final letters separated by spaces). Controls showed a bilateral advantage but dyslexics did not. In Experiments 1 and 3, the dyslexics showed significantly lower accuracy for LVF trials than controls, but the groups did not differ for RVF trials. The findings suggest that dyslexics have a problem of interhemispheric integration and not a general problem of processing two lexical inputs simultaneously.     

The semantics of prosody: acoustic and perceptual evidence of prosodic correlates to word meaning

This investigation examined whether speakers produce reliable prosodic correlates to meaning across semantic domains and whether listeners use these cues to derive word meaning from novel words. Speakers were asked to produce phrases in infant-directed speech in which novel words were used to convey one of two meanings from a set of antonym pairs (e.g., big/small). Acoustic analyses revealed that some acoustic features were correlated with overall valence of the meaning. However, each word meaning also displayed a unique acoustic signature, and semantically related meanings elicited similar acoustic profiles. In two perceptual tests, listeners either attempted to identify the novel words with a matching meaning dimension (picture pair) or with mismatched meaning dimensions. Listeners inferred the meaning of the novel words significantly more often when prosody matched the word meaning choices than when prosody mismatched. These findings suggest that speech contains reliable prosodic markers to word meaning and that listeners use these prosodic cues to differentiate meanings. That prosody is semantic suggests a reconceptualization of traditional distinctions between linguistic and nonlinguistic properties of spoken language.     

Protein analysis meets visual word recognition: a case for string kernels in the brain

It has been recently argued that some machine learning techniques known as Kernel methods could be relevant for capturing cognitive and neural mechanisms ( Jäkel, Schölkopf, & Wichmann, 2009 ). We point out that ‘‘String kernels,’’ initially designed for protein function prediction and spam detection, are virtually identical to one contending proposal for how the brain encodes orthographic information during reading. We suggest some reasons for this connection and we derive new ideas for visual word recognition that are successfully put to the test. We argue that the versatility and performance of String kernels makes a compelling case for their implementation in the brain.     

SUBTLEX-UK: A new and improved word frequency database for British English

We present word frequencies based on subtitles of British television programmes. We show that the SUBTLEX-UK word frequencies explain more of the variance in the lexical decision times of the British Lexicon Project than the word frequencies based on the British National Corpus and the SUBTLEX-US frequencies. In addition to the word form frequencies, we also present measures of contextual diversity part-of-speech specific word frequencies, word frequencies in children programmes, and word bigram frequencies, giving researchers of British English access to the full range of norms recently made available for other languages. Finally, we introduce a new measure of word frequency, the Zipf scale, which we hope will stop the current misunderstandings of the word frequency effect.     

Emotions in word and face processing: Early and late cortical responses

Recent research suggests that emotion effects in word processing resemble those in other stimulus domains such as pictures or faces. The present study aims to provide more direct evidence for this notion by comparing emotion effects in word and face processing in a within-subject design. Event-related brain potentials (ERPs) were recorded as participants made decisions on the lexicality of emotionally positive, negative, and neutral German verbs or pseudowords, and on the integrity of intact happy, angry, and neutral faces or slightly distorted faces. Relative to neutral and negative stimuli both positive verbs and happy faces elicited posterior ERP negativities that were indistinguishable in scalp distribution and resembled the early posterior negativities reported by others. Importantly, these ERP modulations appeared at very different latencies. Therefore, it appears that similar brain systems reflect the decoding of both biological and symbolic emotional signals of positive valence, differing mainly in the speed of meaning access, which is more direct and faster for facial expressions than for words.     

Influences of lexical tone and pitch on word recognition in bilingual infants

Infants' abilities to discriminate native and non-native phonemes have been extensively investigated in monolingual learners, demonstrating a transition from language-general to language-specific sensitivities over the first year after birth. However, these studies have mostly been limited to the study of vowels and consonants in monolingual learners. There is relatively little research on other types of phonetic segments, such as lexical tone, even though tone languages are very well represented across languages of the world. The goal of the present study is to investigate how Mandarin Chinese-English bilingual learners contend with non-phonemic pitch variation in English spoken word recognition. This is contrasted with their treatment of phonemic changes in lexical tone in Mandarin spoken word recognition. The experimental design was cross-sectional and three age-groups were sampled (7.5months, 9months and 11months). Results demonstrated limited generalization abilities at 7.5months, where infants only recognized words in English when matched in pitch and words in Mandarin that were matched in tone. At 9months, infants recognized words in Mandarin Chinese that matched in tone, but also falsely recognized words that contrasted in tone. At this age, infants also recognized English words whether they were matched or mismatched in pitch. By 11months, infants correctly recognized pitch-matched and - mismatched words in English but only recognized tonal matches in Mandarin Chinese.     

Some linguistic determinants of Swedish word recognition

Native Swedish words and words of foreign origin were studied in a word fill-in task (Experiment 1), in a task in which words were explicitly classified as being native or loan words (Experiment 2), and in a lexical decision task in which a small onset asynchrony was introduced in displaying a word's letter pattern (Experiment 3). The findings obtained show that, both in simple printed word recognition and when asked to make explicit judgments about origin, readers are sensitive to phonological features of words not marked in Swedish orthography. It was further found that previewing a substring of word-initial letters which determines a word's root morpheme will prime recognition, whereas previewing a randomly selected pattern of letters inhibits recognition.     

Syntactic context effects on word recognition: A developmental study

In the present study, grammatical context effects on word recognition were examined among skilled and less skilled second and sixth grade readers. Of particular interest was how the word decoding ability may correlate with the grammatical context effect. For this purpose the rich case-marking system of the Finnish language was exploited. Recognition latencies for sentence-final nouns were measured as a function of their syntactic agreement with the preceding adjective. The naming and lexical decision tasks were used as critical measures.
The study showed a clear syntactic context effect for each of the four experimental groups. The magnitude of the observed syntactic effect was substantially larger compared to earlier results. Furthermore, the effect emerged both in naming and lexical decision. In naming, less skilled 2nd grade decoders were more affected by grammatical incongruency than their more competent peers, whereas in lexical decision the skilled 6th graders differed from other groups by showing a smaller syntactic effect. The results are discussed in the light of Stanovich's interactive-compensatory model of word recognition.