Hebb learning, verbal short-term memory, and the acquisition of phonological forms in children

Recent work using the Hebb effect as a marker for implicit long-term acquisition of serial order has demonstrated a functional equivalence across verbal and visuospatial short-term memory. The current study extends this observation to a sample of five- to six-year-olds using verbal and spatial immediate serial recall and also correlates the magnitude of Hebb learning with explicit measures of word and nonword paired-associate learning. Comparable Hebb effects were observed in both domains, but only nonword learning was significantly related to the magnitude of Hebb learning. Nonword learning was also independently related to individuals' general level of verbal serial recall. This suggests that vocabulary acquisition depends on both a domain-specific short-term memory system and a domain-general process of learning through repetition.     

The phonological store abandoned

Baddeley and Larsen (2007) argue that a number of key findings reported by Jones, Macken, and Nicholls (2004) and Jones, Hughes, and Macken (2006) pointing to shortcomings of the phonological store construct arise from the store being abandoned with long lists. In our rejoinder we point out that Baddeley and Larsen use a procedure in which retrieval from the supposed phonological storage would not—according to their own theory—have been possible, and we present theoretical, empirical, and logical problems with their “store abandonment” argument and highlight a number of difficulties associated with the interpretation of suffix and prefix effects. We conclude that our data are still problematic for the phonological store construct and suggest that a reformulation of short-term memory theory needs to embody (or indeed focus exclusively upon) perceptual and effector systems rather than bespoke storage modules.     

Learning nonwords: the Hebb repetition effect as a model of word learning

Page and Norris [(2008). Is there a common mechanism underlying word-form learning and the Hebb repetition effect? Experimental data and a modelling framework. In A. Thorn &; M. P. A. Page (Eds.), Interactions between short-term and long-term memory in the verbal domain; (2009). A model linking immediate serial recall, the Hebb repetition effect and the learning of phonological word forms. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1536), 3737–3753. doi:10.1098/rstb.2009.0173] have suggested that the Hebb [(1961). Distinctive features of learning in the higher animal. In J. F. Delafresnaye (Ed.), Brain mechanisms and learning (pp. 37–46). Oxford: Blackwell] repetition paradigm can be considered as a laboratory analogue of word learning. In Hebb learning experiments, the lists of items to be learned are presented as discrete sequences. In contrast, novel words are, by definition, always heard as a single coarticulated whole. Might this undermine the claim that Hebb learning can shed light on word learning? Here we report an experiment comparing learning sequences of isolated syllables with learning the same sequences spoken as a single coarticulated nonword. The pattern of learning was similar in the two cases, suggesting that the Hebb repetition paradigm can indeed provide valuable insights into the way novel word forms are learned.     

Vocabulary learning in primary school children: Working memory and long-term memory components

The goal of this study was to investigate which working memory and long-term memory components predict vocabulary learning. We used a nonword learning paradigm in which 8- to 10-year-olds learned picture-nonword pairs. The nonwords varied in length (two vs. four syllables) and phonology (native sounding vs. including one Russian phoneme). Short, phonologically native nonwords were learned best, whereas learning long nonwords leveled off after a few presentation cycles. Linear structural equation analyses showed an influence of three constructs—phonological sensitivity, vocabulary knowledge, and central attentional resources (M capacity)—on nonword learning, but the extent of their contributions depended on specific characteristics of the nonwords to be learned. Phonological sensitivity predicted learning of all nonword types except short native nonwords, vocabulary predicted learning of only short native nonwords, and M capacity predicted learning of short nonwords but not long nonwords. The discussion considers three learning processes—effortful activation of phonological representations, lexical mediation, and passive associative learning—that use different cognitive resources and could be involved in learning different nonword types.     

Commentary on Baddeley and Larsen (2007). The phonological store abandoned

Baddeley and Larsen (2007) argue that a number of key findings reported by Jones, Macken, and Nicholls (2004) and Jones, Hughes, and Macken (2006) pointing to shortcomings of the phonological store construct arise from the store being abandoned with long lists. In our rejoinder we point out that Baddeley and Larsen use a procedure in which retrieval from the supposed phonological storage would not--according to their own theory--have been possible, and we present theoretical, empirical, and logical problems with their "store abandonment" argument and highlight a number of difficulties associated with the interpretation of suffix and prefix effects. We conclude that our data are still problematic for the phonological store construct and suggest that a reformulation of short-term memory theory needs to embody (or indeed focus exclusively upon) perceptual and effector systems rather than bespoke storage modules.     

Short-term memory for serial order supports vocabulary development: New evidence from a novel word learning paradigm

Although recent studies suggest a strong association between short-term memory (STM) for serial order and lexical development, the precise mechanisms linking the two domains remain to be determined. This study explored the nature of these mechanisms via a microanalysis of performance on serial order STM and novel word learning tasks. In the experiment, 6- and 7-year-old children were administered tasks maximizing STM for either item or serial order information as well as paired-associate learning tasks involving the learning of novel words, visual symbols, or familiar word pair associations. Learning abilities for novel words were specifically predicted by serial order STM abilities. A measure estimating the precision of serial order coding predicted the rate of correct repetitions and the rate of phoneme migration errors during the novel word learning process. In line with recent theoretical accounts, these results suggest that serial order STM supports vocabulary development via ordered and detailed reactivation of the novel phonological sequences that characterize new words.     

The relationships among verbal short-term memory, phonological awareness, and new word learning: evidence from typical development and Down syndrome

This study examined the correlates of new word learning in a sample of 64 typically developing children between 5 and 8 years of age and a group of 22 teenagers and young adults with Down syndrome. Verbal short-term memory and phonological awareness skills were assessed to determine whether learning new words involved accurately representing phonological information in memory. Results showed a relationship between verbal short-term memory measures and typically developing individuals’ ability to learn the phonological form of novel words but not their ability to learn the physical referent of new words. Similarly, individuals with Down syndrome showed impaired verbal short-term memory and impaired form but not referent learning. Together, these findings specify the circumstances in which an accurate phonological representation within short-term memory is required for new word learning.     

Lexical learning in bilingual adults: the relative importance of short-term memory for serial order and phonological knowledge

Studies of monolingual speakers have shown a strong association between lexical learning and short-term memory (STM) capacity, especially STM for serial order information. At the same time, studies of bilingual speakers suggest that phonological knowledge is the main factor that drives lexical learning. This study tested these two hypotheses simultaneously in participants with variable levels of English-French bilingual proficiency. A word-nonword paired-associate learning task was administered, with nonwords obeying French phonotactic patterns. French phonological knowledge was estimated by a composite French proficiency score summarizing productive and receptive French vocabulary knowledge as well as quantitative and qualitative measures of French exposure. STM measures maximized retention of order information (serial order reconstruction) or retention of phonological item information (single nonword delayed repetition). The French proficiency score and the serial order STM measure independently predicted performance on the paired-associate learning task. These results highlight the conjoined role of phonological knowledge and serial order STM in lexical learning. Importantly, serial order STM remains a strong predictor of lexical learning, even for bilingual individuals who have broad phonological knowledge.     

Phonotactic probability effect in nonword recall and its relationship with vocabulary in monolingual and bilingual preschoolers

The current study examined to what extent information in long-term memory concerning the distribution of phoneme clusters in a language, so-called long-term phonotactic knowledge, increased the capacity of verbal short-term memory in young language learners and, through increased verbal short-term memory capacity, supported these children’s first and second language vocabulary acquisition. Participants were 67 monolingual Dutch and 60 bilingual Turkish–Dutch 4-year-olds. The superior recall of nonwords with high phonotactic probability compared with nonwords with low phonotactic probability indicated that phonotactic knowledge was supportive for verbal short-term recall in both languages. The extent of this support depended on prior experiences with the language: The Turkish–Dutch children showed a greater phonotactic probability effect in their native language Turkish compared with their Dutch peers, and the monolingual Dutch children outperformed the bilingual Turkish–Dutch children in their native language Dutch. Regression analyses showed that phonotactic knowledge, indicated by the difference in recall of nonwords with high versus low phonotactic probability, was an important predictor of vocabulary in both languages.     

Relations among language exposure, phonological memory, and language development in Spanish-English bilingually developing 2-year-olds

The relation of phonological memory to language experience and development was investigated in 41 Spanish-English bilingual first language learners. The children’s relative exposure to English and Spanish and their phonological memory for English- and Spanish-like nonwords were assessed at 22 months of age, and their productive vocabulary and grammar in both languages were assessed at 25 months of age. Phonological memory for English-like nonwords was highly correlated with that for Spanish-like nonwords, and each was related to vocabulary and grammar in both languages, suggesting a language-general component to phonological memory skill. In addition, there was evidence of language-specific benefits of language exposure to phonological memory skill and of language-specific benefits of phonological memory skill to language development.     

Irrelevant speech effects and statistical learning

Immediate serial recall of visually presented verbal stimuli is impaired by the presence of irrelevant auditory background speech, the so-called irrelevant speech effect. Two of the three main accounts of this effect place restrictions on when it will be observed, limiting its occurrence either to items processed by the phonological loop (the phonological loop hypothesis) or to items that are not too dissimilar from the irrelevant speech (the feature model). A third, the object-oriented episodic record (O-OER) model, requires only that the memory task involves seriation. The present studies test these three accounts by examining whether irrelevant auditory speech will interfere with a task that does not involve the phonological loop, does not use stimuli that are compatible with those to be remembered, but does require seriation. Two experiments found that irrelevant speech led to lower levels of performance in a visual statistical learning task, offering more support for the O-OER model and posing a challenge for the other two accounts.     

Cross-modal working memory binding and learning of visual-phonological associations in children with reading difficulties

Reading decoding requires the association of a visual input (the printed word) with a verbal output (the spoken word), and the learning of visual-phonological associations via repeated exposure occurs both explicitly (by instruction and training) and implicitly (by exposure to written material). However, a general ability to implicitly learn visual-phonological associations (or cross-modal bindings) in children with reading difficulties (RD) has not been deeply explored. The present paper examined this issue in two studies comparing groups of children with RD with matched groups of control children in a working memory binding task involving sequences of variable combinations of nonsense shapes and nonwords (odd trials), as well as fixed combinations (even trials). Stimuli presentation was followed by a recognition test in which the nonwords were given one at a time and the children were required to mouse click on their respective shapes. In Study 1, fixed bindings were presented in random sequences across even trials, and the recognition test presented the nonwords at random. In Study 2, fixed bindings were presented in the same order across even trials, and the recognition test presented the nonwords following the same sequence order. In both studies, a consistent and strong learning effect of fixed bindings was observed for the control groups, with significantly better performance than the groups with RD. Such results suggest that poor cross-modal binding learning is associated with reading difficulties. Implications for the study and treatment of dyslexia are discussed.     

SKOOL versus ZOOL: Effects of orthographic and phonological long-term memory on nonword immediate serial recall

People can acquire both true and false knowledge about the world from fictional stories. The present study explored whether the benefits and costs of learning about the world from fictional stories extend beyond memory for directly stated pieces of information. Of interest was whether readers would use correct and incorrect story references to make deductive inferences about related information in the story, and then integrate those inferences into their knowledge bases. Participants read stories containing correct, neutral, and misleading references to facts about the world; each reference could be combined with another reference that occurred in a later sentence to make a deductive inference. Later they answered general knowledge questions that tested for these deductive inferences. The results showed that participants generated and retained the deductive inferences regardless of whether the inferences were consistent or inconsistent with world knowledge, and irrespective of whether the references were placed consecutively in the text or separated by many sentences. Readers learn more than what is directly stated in stories; they use references to the real world to make both correct and incorrect inferences that are integrated into their knowledge bases.     

The Hebb repetition effect as a laboratory analogue of novel word learning

The present study tests the hypothesis that a common ordering mechanism underlies both short-term serial recall of verbal materials and the acquisition of novel long-term lexical representations, using the Hebb repetition effect. In the first experiment, participants recalled visually presented nonsense syllables following a typical Hebb effect learning protocol. Replicating the Hebb repetition effect, we observed improved recall for repeated sequences of syllables. In the second experiment, the same participants performed an auditory lexical decision task, which included nonwords that were constructed from the syllables used in the first experiment. We observed inhibited rejection of nonwords that were composed of the repeated Hebb sequences, compared to nonwords that were built from nonrepeated filler sequences. This suggests that a long-term phonological lexical representation developed during Hebb learning. Accordingly, the relation between immediate serial recall and word learning is made explicit by arguing that the Hebb repetition effect is a laboratory analogue of naturalistic vocabulary acquisition.     

Parsing of algebraic expressions by experienced users of mathematics

The present study investigates how experienced users of mathematics parse algebraic expressions. The main issues examined are the order in which the symbols in an expression are scanned and the duration of fixation. Two experiments tracked the order in which the symbols of an expression were scanned. The results were analysed using Markov Chain models of the scanpath data and provided strong support for the hypothesised scanning order: a left-to-right, top-to-bottom syntax-based scanning order. Length of fixation was also analysed in the first experiment. When reading text, readers pause significantly longer at the end of clauses and sentences. A similar pattern was found for mathematical expressions: Symbols at the end of a phrasal constituent were fixated upon for significantly longer than symbols at the start or middle of the phrasal constituent. These results suggest that the parsing of algebraic expressions has marked similarities with the way in which sentences of natural language are processed and reinforces the importance of syntax in their comprehension.     

The phonological similarity effect in serial recognition

An experiment is reported examining the effect of consistent phonemic similarity among list items on memory retention in a task that is independent of overt speech production, the serial recognition task. Lists of consonant-vowel-consonant (CVC) words and nonwords were constructed such that although phoneme overlap was manipulated (i.e., shared vowel and final consonant [_VC], initial consonant and vowel [CV_], or the two consonants [C_C]), similarity remained constant. The results show that the influence of sub-syllabic mechanisms on STM performance is independent of speech production processes, and similarity in the pattern of results suggests that the same mechanisms subserve the recall of words and nonwords in STM. It is argued that the results are more consistent with psycholinguistic models than nonlinguistic models of STM, and implications for current STM models are discussed.     

Evidence for knowledge of the syntax of large numbers in preschoolers

The aim of this study was to provide evidence for knowledge of the syntax governing the verbal form of large numbers in preschoolers long before they are able to count up to these numbers. We reasoned that if such knowledge exists, it should facilitate the maintenance in short-term memory of lists of lexical primitives that constitute a number (e.g., three hundred forty five) compared with lists containing the same primitives but in a scrambled order (e.g., five three forty hundred). The two types of lists were given to 5-year-olds in an immediate serial recall task. As we predicted, the lists in syntactic order were easier to recall, suggesting that they match some knowledge of the way lexical primitives must be ordered to express large numerosities.     

The explicit learning of new names for known objects is improved by dexamphetamine

A randomised, double-blind, placebo-controlled, between subjects study design (N=37) was used to investigate the effects of dexamphetamine on explicit new name learning. Participants ingested 10mg of dexamphetamine or placebo daily over 5 consecutive mornings before learning new names for 50 familiar objects plus fillers. The dexamphetamine group recognised and recalled the new names more accurately than the placebo group over the 5 days and 1 month later. Word learning success was not associated with baseline neuropsychological performance, mood, cardiovascular arousal, or sustained attention. These results may have implications for the pharmacological treatment of acquired naming difficulties.     

语音短时记忆与词汇知识对第二语言词汇学习的影响

选取两种语音熟悉程度不同的非词为实验材料,把语音短时记忆区分为项目短时记忆和序列短时记忆,考察语音短时记忆与词汇知识对汉英双语者第二语言（英语）词汇学习的影响。实验1采用产出性的方式进行学习,结果发现,词汇知识与项目短时记忆对语音熟悉非词的学习起预测作用;词汇知识与序列短时记忆对语音不熟悉非词学习起预测作用。实验2采用接受性的方式进行学习,结果发现,项目短时记忆、序列短时记忆和词汇知识都对语音熟悉非词学习起独立的预测作用;项目短时记忆和序列短时记忆对语音不熟悉非词学习起独立的预测作用。实验结果表明,语音短时记忆和词汇知识都是影响英语词汇学习的重要因素。具体而言,学习语音熟悉的词汇,词汇知识起着更为重要的作用;学习语音不熟悉的词汇,语音短时记忆、特别是序列短时记忆起着更为重要的作用,而且两者作用的大小随着词汇学习方式的不同而发生变化。     

Working memory and vocabulary development in Greek preschool and primary school children

The present research investigated the relative contributions of verbal short-term memory (STM) and working memory (WM) to vocabulary development in the early years among Greek-speaking children. Participants were 5.5-, 7.5-, 8.5- and 9.5-year-old (N = 216) native speakers of Greek, a language differing from English in which most investigations have been conducted. Children were assessed with a receptive vocabulary task, four verbal STM measures (word, digit, and non-word list recall, as well as word list matching), and three verbal WM tasks (listening, counting, and backward digit recall). Results offer support to the view that both STM and WM influence vocabulary development in early stages. Vocabulary was associated with verbal STM at 7.5 and 8.5 years, but only with verbal WM at 5.5 years. Associations declined with age (by 9.5 years), earlier than in English-speaking children. Findings are discussed in relation to Greek language characteristics, demonstrating the importance of cross-cultural investigations.