Bootstrapping the early lexicon: how do children use old knowledge to create new meanings?

Compared to other aspects of language development, such as acquiring grammar, we perhaps take for granted the complexity of building a lexicon. More than 50 years ago the philosopher W.V.O. Quine provided a now famous example of what makes word learning so difficult. In short, Quine (1960) argues that when we hear a new word, how can we ever precisely determine its meaning? This problem has concerned many child language researchers, who all acknowledge that the child requires a means of narrowing down the infinite possible meanings of a word. However, researchers have advocated contrasting theoretical perspectives on how this problem is solved. For many, the child's ability to learn new words requires external input from the speaker—not just the word uttered, but also overt “clues” such as pointing and eye gaze (e.g., Bloom, 2000). Others argue that the child brings their own tools to the task, whether in the form of domain-specific heuristics (e.g., Golinkoff et al., 1994), or domain-general mechanisms (e.g., Samuelson and Smith, 2000).One simple solution is to use existing vocabulary knowledge to decode the meanings of new words. This strategy is commonly known as mutual exclusivity—the assumption that an object can only have one name (Markman, 1989, 1990). If a child is faced with more than one possible referent of a new word, she will map the word to whichever referent they cannot name. Word learning in this manner is a form of “bootstrapping” in language development, where existing lexical knowledge can be exploited in order to acquire new lexical knowledge. Alternative explanations of this word learning behavior include the novel-name-nameless-category (N3C) principle (Mervis and Bertrand, 1994) and the principle of contrast (Clark, 1987). In spite of extensive research into mutual exclusivity (and related theoretical accounts), many aspects of this phenomenon are not well-understood, such as the underlying cognitive mechanisms and developmental origins

Novelty, attention, and challenges for developmental psychology

In this brief essay, I seek to demonstrate the significance of exploratory behavior for understanding cognitive development. Historically, organisms were thought to act solely in the service of achieving biologically significant goals, such as satisfying thirst, hunger, and reproductive drives. However, it became apparent that both animals and humans engage in behavior where the adaptive goal is unclear (see Hunt, 1963, 1965). With no obvious external target, this activity is best described as being intrinsically motivated, and often directed toward the unknown and the unexpected (Kagan, 2002). Hence novelty, the discrepancy between what is known and what is discovered, can elicit activity and exploration of the environment.What is the relevance to developmental process? Attention to novelty plays a seemingly simple role in learning and development, directing the senses toward what is as yet unknown. Yet, research shows that patterns of attention to novelty are not straightforward, particularly during infancy. There is considerable evidence that attention is sometimes biased toward familiarity, rather than novelty. Unlike our understanding of novelty preference, we struggle to understand when and why familiarity preferences occur. Below I briefly review this area of research and illustrate how this basic aspect of learning continues to puzzle developmental psychologists

Young children's referent selection is guided by novelty for both words and actions

Young children are biased to select novel, name-unknown objects as referents of novel labels (e.g., Markman, 1990) and similarly favour novel, action-unknown objects as referents of novel actions (Riggs, Mather, Hyde & Simpson, 2015). What process underlies these common behaviors? In the case of word learning, children may be driven by a novelty bias favouring novel objects as referents (Horst, Samuelson, Kucker & McMurray, 2011). Our study investigates this bias further by investigating whether novelty also affects children’s selection of novel objects when a new action is given. In a pre-exposure session, 40, three- and four-year-olds were shown eight novel objects for one minute. In subsequent referent selection trials children were shown two pre-exposed and one super-novel object and heard either a novel name or saw a novel action. The super-novel object was selected significantly more that the pre-exposed objects on both word and action trials. Our data add to the growing literature suggesting that an endogenous attentional bias to novelty plays a role in children’s referent selection and demonstrates further parallels between word and action learning

Get your facts right : preschoolers systematically extend both object names and category-relevant facts

There is an ongoing debate over the extent to which language development shares common processing mechanisms with other domains of learning. It is well-established that toddlers will systematically extend object labels to similarly-shaped category exemplars (e.g., Landau, Smith, & Jones, 1988; Markman & Hutchinson, 1984). However, previous research is inconclusive as to whether young children will similarly extend factual information about an object to other category members. We explicitly contrast facts varying in category relevance, and test for extension using two different tasks. Three- to four-year-olds (N = 61) were provided with one of three types of information about a single novel object: a category-relevant fact (‘it’s from a place called Modi’), a category-irrelevant fact (‘my uncle gave it to me’), or an object label (‘it’s called a Modi’). At test, children provided with the object name or category-relevant fact were significantly more likely to display systematic category extension than children who learnt the category-irrelevant fact. Our findings contribute to a growing body of evidence that the mechanisms responsible for word learning may be domain-general in nature

Functional Genomics Tool: Gene Silencing in \u3ci\u3eIxodes scapularis\u3c/i\u3e Eggs and Nymphs by Electroporated dsRNA

Background Ticks are blood-sucking arthropods responsible for transmitting a wide variety of disease-causing agents, and constitute important public health threats globally. Ixodes scapularis is the primary vector of the Lyme disease agent in the eastern and central U.S. RNAi is a mechanism by which gene-specific double-stranded RNA (dsRNA) triggers degradation of homologous mRNA transcripts. Here, we describe an optimized protocol for effectively suppressing gene expression in the egg and nymphal stages of I. scapularis by electroporation. Results The genes encoding the putative Phospholipase A2 (PLA2), cytoplasmic Cystatin, Syntaxin-5, β-Actin and Calreticulin were targeted by delivering the dsRNA encoding the specific gene coding regions in the unfed nymphs. Silencing was measured using real time qRT-PCR. Electroporation as a mode of dsRNA delivery appears to be substantially efficient and less traumatic to the tick than dsRNA microinjection in the unfed nymphs. Using Cy3-labeled dsRNA to monitor the movement, electroporated dsRNA entered the nymphs and spread to salivary glands and other tissues. The significant disruption of β-actin and cytoplasmic Cystatin transcripts in tick eggs demonstrate the applicability of this technique. The PLA2, cytoplasmic Cystatin, Syntaxin-5, β-Actin and Calreticulin genes were also significantly silenced, suggesting that this method has the potential to introduce dsRNA in eggs and unfed nymphs. Conclusions Our study demonstrates that electroporation can be used as a simple dsRNA delivery tool in assessing the functional role of tick genes in the vector-host interactions. This technique represents a novel approach for specific gene suppression in immature stages of ticks

Functional genomics tool: Gene silencing in Ixodes scapularis eggs and nymphs by electroporated dsRNA

Background: Ticks are blood-sucking arthropods responsible for transmitting a wide variety of disease-causing agents, and constitute important public health threats globally. Ixodes scapularis is the primary vector of the Lyme disease agent in the eastern and central U.S. RNAi is a mechanism by which gene-specific double-stranded RNA (dsRNA) triggers degradation of homologous mRNA transcripts. Here, we describe an optimized protocol for effectively suppressing gene expression in the egg and nymphal stages of I. scapularis by electroporation. Results: The genes encoding the putative Phospholipase A2 (PLA2), cytoplasmic Cystatin, Syntaxin-5, β-Actin and Calreticulin were targeted by delivering the dsRNA encoding the specific gene coding regions in the unfed nymphs. Silencing was measured using real time qRT-PCR. Electroporation as a mode of dsRNA delivery appears to be substantially efficient and less traumatic to the tick than dsRNA microinjection in the unfed nymphs. Using Cy3-labeled dsRNA to monitor the movement, electroporated dsRNA entered the nymphs and spread to salivary glands and other tissues. The significant disruption of β-actin and cytoplasmic Cystatin transcripts in tick eggs demonstrate the applicability of this technique. The PLA2, cytoplasmic Cystatin, Syntaxin-5, β-Actin and Calreticulin genes were also significantly silenced, suggesting that this method has the potential to introduce dsRNA in eggs and unfed nymphs. Conclusions: Our study demonstrates that electroporation can be used as a simple dsRNA delivery tool in assessing the functional role of tick genes in the vector-host interactions. This technique represents a novel approach for specific gene suppression in immature stages of ticks

RNAi-mediated gene silencing in tick synganglia: A proof of concept study

<p>Abstract</p> <p>Background</p> <p>Progress in generating comprehensive EST libraries and genome sequencing is setting the stage for reverse genetic approaches to gene function studies in the blacklegged tick (<it>Ixodes scapularis</it>). However, proving that RNAi can work in nervous tissue has been problematic. Developing an ability to manipulate gene expression in the tick synganglia likely would accelerate understanding of tick neurobiology. Here, we assess gene silencing by RNA interference in the adult female black-legged tick synganglia.</p> <p>Results</p> <p>Tick β-Actin and Na⁺-K⁺-ATPase were chosen as targets because both genes express in all tick tissues including synganglia. This allowed us to deliver dsRNA in the unfed adult female ticks and follow a) uptake of dsRNA and b) gene disruption in synganglia. <it>In vitro </it>assays demonstrated total disruption of both tick β-Actin and Na⁺-K⁺-ATPase in the synganglia, salivary glands and midguts. When dsRNA was microinjected in unfed adult female ticks, nearly all exhibited target gene disruption in the synganglia once ticks were partially blood fed.</p> <p>Conclusion</p> <p>Abdominal injection of dsRNA into unfed adult female ticks appears to silence target gene expression even in the tick synganglia. The ability of dsRNA to cross the blood-brain barrier in ticks suggests that RNAi should prove to be a useful method for dissecting function of synganglia genes expressing specific neuropeptides in order to better assess their role in tick biology.</p

Characteristics of Australian cohort study participants who do and do not take up an additional invitation to join a long-term biobank: The 45 and Up Study

BACKGROUND Large-scale population biobanks are critical for future research integrating epidemiology, genetic, biomarker and other factors. Little is known about the factors influencing participation in biobanks. This study compares the characteristics of biobank participants with those of non-participants, among members of an existing cohort study. METHODS Individuals aged 45 and over participating in The 45 and Up Study and living ≤20km from central Wagga Wagga, New South Wales (NSW), Australia (rural/regional area) or ≤10km from central Parramatta, NSW (urban area) (n=2340) were invited to join a biobank, giving a blood sample and having additional measures taken, including height, weight, waist circumference, heart rate and blood pressure. RESULTS The overall uptake of the invitation to participate was 33% (762/2340). The response rate was 41% (410/1002) among participants resident in the regional area, and 26% (352/1338) among those resident in the urban area. Characteristics associated with significantly decreased participation were being aged 80 and over versus being aged 45-64 (participation rate ratio: RR = 0.45, 95%CI 0.34-0.60), not being born in Australia versus being born in Australia (0.69, 0.59-0.81), having versus not having a major disability (0.54, 0.38-0.76), having full-time caregiving responsibilities versus not being a full-time carer (0.62, 0.42-0.93) and being a current smoker versus never having smoked (0.66, 0.50-0.89). Factors associated with increased participation were being in part-time work versus not being in paid work (1.24, 1.07-1.44) and having an annual household income of ≥$50,000 versus <$20,000 (1.50, 1.26-1.80). CONCLUSIONS A range of socio-economic, health and lifestyle factors are associated with biobank participation among members of an existing cohort study, with factors relating to health-seeking behaviours and access difficulties or time limitations being particularly important. If more widespread participation in biobanking is desired, particularly to ensure sufficient numbers among those most affected by these issues, specific efforts may be required to increase participation in certain groups such as migrants, the elderly, and those in poor health. Whilst caution should be exercised when generalising estimates of absolute prevalence from biobanks, estimates for many internal comparisons are likely to remain valid.This specific project was funded by The Cancer Council NSW. Emily Banks is supported by the National Health and Medical Research Council

Randomised trial investigating the relationship of response rate for blood sample donation to site of biospecimen collection, fasting status and reminder letter: The 45 and Up Study

BACKGROUND Various options exist for collecting biospecimens and biomarkers from cohort study participants, and these have important logistic, resource and scientific implications. Evidence on how different collection methods affect participation and data quality is lacking. This parallel-design randomised trial, the Link-Up Study, involved blood sample donation and other data collection among participants in an existing cohort study, The 45 and Up Study. It aimed to investigate the relation of fasting status, reminder letters and data collection site to response rates, data quality and biospecimen yield. METHODS Individuals aged 45 and over participating in The 45 and Up Study and living ≤ 20 km from central Wagga Wagga, NSW (regional area) or ≤ 10 km from central Parramatta, NSW (urban area) (n=2340) were randomised, stratified by area of residence, to be invited to give a blood sample and additional data by attending either a clinic established specifically for the trial, with an appointment time ("dedicated clinic", n=1336) or an existing local commercial pathology centre (n=1004). Within dedicated clinic groups, participants were randomised into fasting (n=668) or non-fasting (n=668) and, at the Parramatta pathology centre site, reminder letter after two weeks (n=336) or no reminder (n=334). RESULTS Overall, 33% (762/2340) of invitees took part in the Link-Up Study; 41% (410/1002) among regional and 26% (352/1338) among urban-area residents (p<0.0001). At the dedicated clinics, response rates were 38% (257/668) not fasting and 38% fasting (257/668) (participation rate ratio (RR) =1.00, 95%CI 0.91-1.08, p=0.98). The response rate was 22% among individuals randomised to attend the Parramatta pathology centre without a reminder and 23% among those sent a reminder letter (RR=1.01, 0.93-1.09, p=0.74). In total, the response rate was 38% (514/1336) at the dedicated clinics and 25% (248/1004) at the pathology centres (RR=0.67, 0.56-0.78, p<0.01); measures of height, weight and systolic and diastolic blood pressure did not vary materially between these groups, nor did the median number of aliquots of plasma, buffy coat and red cells collected. CONCLUSIONS Among cohort study participants, response rates for an additional study involving biospecimen collection, but not data quality or average biospecimen yield, were considerably higher at dedicated clinics than at existing commercial pathology sites.This specific project was funded by The Cancer Council NSW. Emily Banks is supported by the National Health and Medical Research Council

The role of systematicity in early referent selection

Previous studies showed that word learning is affected by children's existing knowledge. For instance, knowledge of semantic category aids word learning, whereas a dense phonological neighbourhood impedes learning of similar-sounding words. Here, we examined to what extent children associate similar-sounding words (e.g., rat and cat) with objects of the same semantic category (e.g., both are animals), that is, to what extent children assume meaning overlap given form overlap between two words. We tested this by first presenting children (N = 93, Mage = 22.4months) with novel word-object associations. Then, we examined the extent to which children assume that a similar sounding novel label, that is, a phonological neighbour, refers to a similar looking object, that is, a likely semantic neighbour, as opposed to a dissimilar looking object. Were children to preferentially fixate the similar-looking novel object, it would suggest that systematic word form-meaning relations aid referent selection in young children. While we did not find any evidence for such word form-meaning systematicity, we demonstrated that children showed robust learning for the trained novel word-object associations, and were able to discriminate between similar-sounding labels and also similar-looking objects. Thus, we argue that unlike iconicity which appears early in vocabulary development, we find no evidence for systematicity in early referent selection