Age constraints on first versus second language acquisition: evidence for linguistic plasticity and epigenesis

Does age constrain the outcome of all language acquisition equally regardless of whether the language is a first or second one? To test this hypothesis, the English grammatical abilities of deaf and hearing adults who either did or did not have linguistic experience (spoken or signed) during early childhood were investigated with two tasks, timed grammatical judgement and untimed sentence to picture matching. Findings showed that adults who acquired a language in early life performed at near-native levels on a second language regardless of whether they were hearing or deaf or whether the early language was spoken or signed. By contrast, deaf adults who experienced little or no accessible language in early life performed poorly. These results indicate that the onset of language acquisition in early human development dramatically alters the capacity to learn language throughout life, independent of the sensory-motor form of the early experience.     

Skilled deaf readers have an enhanced perceptual span in reading

Recent evidence suggests that, compared with hearing people, deaf people have enhanced visual attention to simple stimuli viewed in the parafovea and periphery. Although a large part of reading involves processing the fixated words in foveal vision, readers also utilize information in parafoveal vision to preprocess upcoming words and decide where to look next. In the study reported here, we investigated whether auditory deprivation affects low-level visual processing during reading by comparing the perceptual span of deaf signers who were skilled and less-skilled readers with the perceptual span of skilled hearing readers. Compared with hearing readers, the two groups of deaf readers had a larger perceptual span than would be expected given their reading ability. These results provide the first evidence that deaf readers' enhanced attentional allocation to the parafovea is used during complex cognitive tasks, such as reading.     

Transitional information in spatial serial memory: path characteristics affect recall performance

This study examined the role of stimulus characteristics in a visuospatial order reconstruction task in which participants were required to recall the order of sequences of spatial locations. The complexity of the to-be-remembered sequences, as measured by path crossing, path length, and angles, was found to affect serial memory, in terms of both recall accuracy and response times. The results demonstrate that not all sequences are remembered equally and that spatial characteristics of the sequences constitute an important variable in the understanding of visuospatial serial memory. More important, the data suggest that spatial path represents transitional information and that, as is the case in verbal serial memory, transitional information is of critical importance in serial memory.     

Gesture Reflects Language Development: Evidence From Bilingual Children

There is a growing awareness that language and gesture are deeply intertwined in the spontaneous expression of adults. Although some research suggests that children use gesture independently of speech, there is scant research on how language and gesture develop in children older than 2 years. We report here on a longitudinal investigation of the relation between gesture and language development in French-English bilingual children from 2 to 3 1/2 years old. The specific gesture types of iconics and beats correlated with the development of the children's two languages, whereas pointing types of gestures generally did not. The onset of iconic and beat gestures coincided with the onset of sentencelike utterances separately in each of the children's two languages. The findings show that gesture is related to language development rather than being independent from it. Contrasting theories about how gesture is related to language development are discussed.     

Subjective frequency ratings for 432 ASL signs

Given the importance of lexical frequency for psycholinguistic research and the lack of comprehensive frequency data for sign languages, we collected subjective estimates of lexical frequency for 432 signs in American Sign Language (ASL). Our participants were 59 deaf signers who first began to acquire ASL at ages ranging from birth to 14 years old and who had a minimum of 10 years of experience. Subjective frequency estimates were made on a scale ranging from 1 = rarely see the sign to 7 = always see the sign. The mean subjective frequency ratings for individual signs did not vary in relation to age of sign language exposure (AoLE), chronological age, or length of ASL experience. Nor did AoLE show significant effects on the response times (RTs) for making the ratings. However, RTs were highly correlated with mean frequency ratings. These results suggest that the distributions of subjective lexical frequencies are consistent across signers with varying AoLEs. The implications for research practice are that subjective frequency ratings from random samples of highly experienced deaf signers can provide a reasonable measure of lexical control in sign language experiments. The Appendix gives the mean and median subjective frequency ratings and the mean and median log(RT) of the ASL signs for the entire sample; the supplemental material gives these measures for the three AoLE groups: native, early, and late.     

Rapid learning of rapid temporal contexts

In an information-rich visual world and with limited attentional resources, what visual cues allow humans to efficiently navigate their environment? One key environmental characteristic is that stimuli rarely appear in isolation and typically coincide with other specific items that provide cues regarding where and when to guide our attention. Indeed, a predictive spatial context of distractors can enhance the deployment of attention to a target location (Chun &; Jiang, 1998). However, can a predictive, temporal sequence of distractors, which do not enter working memory, cue when to allocate attention? Previous studies addressing this question have employed relatively long (?500 msec/item) stimulus exposure durations. Thus, this temporal cuing may require extensive processing of the distractors. Here, we show that a rapidly presented (～100 msec/item), predictive, temporal context, where stimuli undergo only preliminary analysis, can facilitate the deployment of attention to a specific temporal location.     

Gesture and early bilingual development

The relationship between speech and gestural proficiency was investigated longitudinally (from 2 years to 3 years 6 months, at 6-month intervals) in 5 French-English bilingual boys with varying proficiency in their 2 languages. Because of their different levels of proficiency in the 2 languages at the same age, these children's data were used to examine the relative contribution of language and cognitive development to gestural development. In terms of rate of gesture production, rate of gesture production with speech, and meaning of gesture and speech, the children used gestures much like adults from 2 years on. In contrast, the use of iconic and beat gestures showed differential development in the children's 2 languages as a function of mean length of utterance. These data suggest that the development of these kinds of gestures may be more closely linked to language development than other kinds (such as points). Reasons why this might be so are discussed.     

Different clues from different views: the role of image format in public perceptions of neuroimaging results

We examined whether different types of brain images affect readers' evaluations of scientific reports. Five different brain images were selected from the neuroscience literature: a whole brain, an inflated brain, a cross-sectional brain slice, a glass brain, and a topographic map. First, the images were subjectively rated by 31 nonexperts for qualities associated with realism and perceived complexity. Each of the five images was later presented alongside one of five fictitious neuroscience articles (image-text pairings counterbalanced), and a different group of 122 novices rated the accompanying articles for scientific reasoning. They also separately reported their familiarity with each image type. Brain images previously rated as more three-dimensional produced more positive evaluations of the articles with which they were presented. Perceived image complexity also showed a marginal nonlinear relationship with article credibility ratings. Our findings suggest that choice of image format matters when disseminating neuroscience research to the general public.     

Age of acquisition effects on the functional organization of language in the adult brain

Using functional magnetic resonance imaging (fMRI), we neuroimaged deaf adults as they performed two linguistic tasks with sentences in American Sign Language, grammatical judgment and phonemic-hand judgment. Participants’ age-onset of sign language acquisition ranged from birth to 14 years; length of sign language experience was substantial and did not vary in relation to age of acquisition. For both tasks, a more left lateralized pattern of activation was observed, with activity for grammatical judgment being more anterior than that observed for phonemic-hand judgment, which was more posterior by comparison. Age of acquisition was linearly and negatively related to activation levels in anterior language regions and positively related to activation levels in posterior visual regions for both tasks.