Levels of processing and phonological priming in Chinese character completion tests

This study investigated the level of processing (LoP) effect in the Chinese character completion task. Stem cues, either graphemically or phonetically related to a target character, were used to generate two different kinds of perceptual tests. By giving participants either direct or indirect instructions, the character completion tests could be either an explicit or an implicit memory test. For the implicit test, LoP effects were not found between Read and Generation conditions, whereas the Physical condition did not produce priming. In addition, no priming was found when participants received graphemic cues during the test. For the explicit test, on the other hand, a standard pattern of LoP effects was found between the Physical, Read, and Generation conditions. Results are discussed in terms of the importance of lexical access for character completion tests and the role of phonology in processing Chinese characters.     

Structure of preschool phonological sensitivity: overlapping sensitivity to rhyme,words, syllables,and phonemes

Phonological sensitivity is an important causal variable in reading acquisition; however, there is controversy concerning its nature. One view holds that sensitivity to various linguistic units reflects independent abilities, whereas another holds sensitivity to these units reflects one ability. We examined relations among sensitivity to words, syllables, rhymes, and phonemes in 149 older preschool children (4- and 5-year-olds) and 109 younger preschool children (2- and 3-year-olds) who completed eight measures of phonological sensitivity and measures of print knowledge. Confirmatory factor analyses of all combinations of word, syllable, rhyme, and phoneme factors found that a one-factor model best explained the data from both groups of children (CFIs >.98). Only variance common to all phonological sensitivity skills was related to print knowledge and rudimentary decoding. Findings support a developmental conceptualization of phonological sensitivity.     

Learning related modulation of functional retrieval networks in man

The medial temporal lobe has been implicated in studies of episodic memory tasks involving spatio-temporal context and object-location conjunctions. We have previously demonstrated that an increased level of practice in a free-recall task parallels a decrease in the functional activity of several brain regions, including the medial temporal lobe, the prefrontal, the anterior cingulate, the anterior insular, and the posterior parietal cortices, that in concert demonstrate a move from elaborate controlled processing towards a higher degree of automaticity. Here we report data from two experiments that extend these initial observations. We used a similar experimental approach but probed for effects of retrieval paradigms and stimulus material. In the first experiment we investigated practice related changes during recognition of object-location conjunctions and in the second during free-recall of pseudo-words. Learning in a neural network is a dynamic consequence of information processing and network plasticity. The present and previous PET results indicate that practice can induce a learning related functional restructuring of information processing. Different adaptive processes likely subserve the functional re-organisation observed. These may in part be related to different demands for attentional and working memory processing. It appears that the role(s) of the prefrontal cortex and the medial temporal lobe in memory retrieval are complex, perhaps reflecting several different interacting processes or cognitive components. We suggest that an integrative interactive perspective on the role of the prefrontal and medial temporal lobe is necessary for an understanding of the processing significance of these regions in learning and memory. It appears necessary to develop elaborated and explicit computational models for prefrontal and medial temporal functions in order to derive detailed empirical predictions, and in combination with an efficient use and development of functional neuroimaging approaches, to further the understanding of the processing significance of these regions in memory.     

Functional heterogeneity of inferior frontal gyrus is shaped by linguistic experience

A crosslinguistic, positron emission tomography (PET) study was conducted to determine the influence of linguistic experience on the perception of segmental (consonants and vowels) and suprasegmental (tones) information. Chinese and English subjects (10 per group) were presented binaurally with lists consisting of five Chinese monosyllabic morphemes (speech) or low-pass-filtered versions of the same stimuli (nonspeech). The first and last items were targeted for comparison; the time interval between target tones was filled with irrelevant distractor tones. A speeded-response, selective attention paradigm required subjects to make discrimination judgments of the target items while ignoring intervening distractor tones. PET scans were acquired for five tasks presented twice: one passive listening to pitch (nonspeech) and four active (speech = consonant, vowel, and tone; nonspeech = pitch). Significant regional changes in blood flow were identified from comparisons of group-averaged images of active tasks relative to passive listening. Chinese subjects show increased activity in left premotor cortex, pars opercularis, and pars triangularis across the four tasks. English subjects, on the other hand, show increased activity in left inferior frontal gyrus regions only in the vowel task and in right inferior frontal gyrus regions in the pitch task. Findings suggest that functional circuits engaged in speech perception depend on linguistic experience. All linguistic information signaled by prosodic cues engages left-hemisphere mechanisms. Storage and executive processes of working memory that are implicated in phonological processing are mediated in discrete regions of the left frontal lobe.     

Does dyslexia develop from learning the alphabet in the wrong hemisphere? A cognitive neuroscience analysis

A new perspective is described which views developmental dyslexia as the outcome of learning to write the alphabet in the nondominant (right) hemisphere. The letter-level and whole-word subtypes of dyslexia are seen as differing responses adopted to cope with this predicament. Striking similarities between dyslexics and callosotomy patients in the allocation of covert attention to lateralized stimuli provide direction for integrating a diversity of dyslexic research within this framework. This synthesis, together with information from pure alexia, brain activation, and reading research, lends insight into the neural circuitry of the compensatory strategies adopted by the two dyslexic subtypes.     

Linking sight and sound: fMRI evidence of primary auditory cortex activation during visual word recognition

We describe two studies that used repetition priming paradigms to investigate brain activity during the reading of single words. Functional magnetic resonance images were collected during a visual lexical decision task in which nonword stimuli were manipulated with regard to phonological properties and compared to genuine English words. We observed a region in left-hemisphere primary auditory cortex linked to a repetition priming effect. The priming effect activity was observed only for stimuli that sound like known words; moreover, this region was sensitive to strategic task differences. Thus, a brain region involved in the most basic aspects of auditory processing appears to be engaged in reading even when there is no environmental oral or auditory component.     

Early effects of neighborhood density and phonotactic probability of spoken words on event-related potentials

All current models of spoken word recognition propose that sound-based representations of spoken words compete with, or inhibit, one another during recognition. In addition, certain models propose that higher probability sublexical units facilitate recognition under certain circumstances. Two experiments were conducted examining ERPs to spoken words and nonwords simultaneously varying in phonotactic probability and neighborhood density. Results showed that the amplitude of the P2 potential was greater for high probability-density words and nonwords, suggesting an early inhibitory effect of neighborhood density. In order to closely examine the role of phonotactic probability, effects of initial phoneme frequency were also examined. The latency of the P2 potential was shorter for words with high initial-consonant probability, suggesting a facilitative effect of phonotactic probability. The current results are consistent with findings from previous studies using reaction time and eye-tracking paradigms and provide new insights into the time-course of lexical and sublexical activation and competition.     

Reinforcement sensitivity theory and symptoms of personality disorder: Specificity of the BIS in Cluster C and BAS in Cluster B

Gray’s reinforcement sensitivity theory, consisting of the behavioral inhibition (BIS) and behavioral activation (BAS), is frequently used to represent basic dimensions of psychopathology. However, notably few investigations have examined the link between the BIS/BAS and symptoms of personality disorder (PD). Although the Fight-Flight-Freeze System has emerged in the revised model as an important aspect of motivation, the BIS (linked to anxiety) and BAS (linked to impulsivity) have been the primary foci. The current investigation uses a dimensional measure of PD, the schedule for nonadaptive and adaptive personality (SNAP; Clark, 1993) applied to two independent samples of English-speaking participants: undergraduates (n = 276) and clinical patients (n = 47). Results were consistent across both samples, demonstrating that symptoms of Cluster B PDs are indicative of high BAS levels whereas symptoms of Cluster C PDs are characterized by high BIS levels.     

Temperature dependence of the plastic flow behavior of tantalum

Nanoindention has been used to study the plastic flow behavior of bcc Ta(001) in the temperature range 25–200°C. Most notably, it is found that the shape of the load–displacement curves changes with increasing temperature. Only one large discontinuity marking the onset of plasticity is observed in room-temperature experiments, whereas multiple pop-ins separated by elastic reloading segments were observed at 200°C. Detailed analysis of the load–displacement curves indicates that the lattice resistance decreases with increasing temperature, consistent with the mobilization of screw dislocations by thermal activation. Contributions from the oxide layer and/or thermal drift can be excluded.     

双言舌尖现象的产生机制：来自粤语-普通话双言者的证据

舌尖现象(Tip-of-the-Tongue phenomenon, TOT)是言语产生中的一种常见现象。国外研究发现, 双语者和单语者的舌尖现象差异很大。双言和双语既相似, 又存在差异。以粤语–普通话双言者为被试, 比较了普通话熟练和不熟练的被试在使用不同语言命名时的TOT产生率。结果发现：(1)粤语–普通话双言者的TOT率受普通话熟练程度影响。普通话不熟练的粤语–普通话双言者用普通话命名时产生更高的TOT率。(2)语言启动能够调节粤语–普通话双言者的普通话熟练程度与TOT产生的关系。在语言启动条件下, 普通话熟练的粤语–普通话双言者的TOT率更高。(3)粤语–普通话双言者的TOT产生机制符合部分激活理论的预言。