Cerebral asymmetry for speech in neonates: A behavioral measure

This paper reports a finding of hemispheric brain asymmetry for speech in short-gestation infants (mean gestational AGE = 36 weeks). Using a new measure—degree of reduction in limb tremors following exposure to speech stimuli compared to two control groups, one hearing orchestral music, the other no patterned stimuli—we found that speech disproportionately affected right limb movements. It is not clear whether the effect is due to asymmetries in cortical or subcortical processing. This provides evidence against the notion that brain specialization for language functions necessarily appears over time; rather, specialization for some functions (e.g., speech reception) must be present at birth.     

Respond,don’t react: The influence of mindfulness training on performance monitoring in older adults

A sizeable body of literature demonstrates positive effects of mindfulness training on brain, behavior, and psychological processes in both novice and expert practitioners as compared to non-meditators. However, only more recently has research begun to examine the specific mechanisms by which mindfulness exerts these effects. In the current study, we used event-related potentials (error-related negativity (ERN), error positivity (Pe)) to test the hypothesis that performance monitoring is one such mechanism. We conducted a randomized controlled trial in healthy older adults (n = 36), relevant because markers of performance monitoring are known to decline with normal aging. Compared to an active control condition, mindfulness participants showed an increase in the ERN, without an increase in the Pe. Participants in both groups reported a reduction in self-report of anxiety and self-judgment of one’s own mental functioning, indicating the subjective impression of benefit from each intervention type. The current results are important insofar as they support the purported self-regulatory functions of mindfulness (i.e., learning to respond, not react), as well as demonstrating that such positive effects can be obtained in an older adult sample, both of which have important implications for intervention.     

Attention control and ability level in a complex cognitive skill: Attention shifting and second-language proficiency

In this study, we investigated the relationship between attention control and proficiency in a complex cognitive skill. The participants were English-French bilinguals with varying degrees of second-language (French) proficiency. Proficiency was operationalized as efficiency of lexical access in an animacy judgment task, as reflected in the coefficient of variability of response time adjusted for first-language performance on the same task. Attention control was operationalized as the shift cost obtained in a linguistic version of the alternating runs task-switching paradigm. Hierarchical regression revealed that, overall, attention control accounted for 59% of the variance of proficiency and that second-language attention control alone accounted for 32% of the unique variance of proficiency, indicating a high degree of skill domain (second language) specificity in the relationship between attention control and proficiency. The results speak to issues regarding the development of expertise, second-language acquisition, and a cognitive linguistic approach to language and attention.     

Attentional blink differences between adolescent dyslexic and normal readers

The goal of this study was to evaluate the possibility that dyslexic individuals require more working memory resources than normal readers to shift attention from stimulus to stimulus. To test this hypothesis, normal and dyslexic adolescents participated in a Rapid Serial Visual Presentation experiment (Raymond, Shapiro, & Arnell, 1992). Surprisingly, the result showed that the participants with dyslexia produced a shallower attentional blink than normal controls. This result may be interpreted as showing differences in the way the two groups encode information in episodic memory. They also fit in a cascade-effect perspective of developmental dyslexia.     

Task complexity and habituation effects on frontal P300 topography

The P3(00) event-related potential (ERP) component is usually reported as having a centroparietal maximum. However, the P3 topography is more frontal in early-session trials which may be masked by averaging over the entire session and is evident longer into the test session among elderly subjects. This hyperfrontality is interpreted as a sign of poor prefrontal adaptive functioning. In the present study, P3 amplitude was examined in university students to determine how early a change in amplitude would be evident and the effect of task complexity on the amplitude across electrode sites. ERPs were elicited using a working-memory n-back task where participants pressed a key to target letter presentations in three conditions of increasing complexity. Single-trial ERP waveforms were then averaged in successive sequences of five trials. Results revealed a greater decrease in frontal P3 amplitude compared to the central and parietal P3 after the first block of five target trials until the third block. The results are interpreted as indicating rapid decrease in hyperfrontality with habituation to an easy task. Increases in task complexity (the 2-back paradigm), however, reduced this frontal P3 attenuation. Results support a P3 ERP model of hyperfrontality reflecting short-term adaptive function by the prefrontal cortex.     

Lexical access of function versus content words

There has been a simmering debate as to whether evidence exists for differential processes of lexical access for function and content words. This has centered around the frequency effect (higher word frequency reducing access times for content words but not function words). Previous work has used the lexical decision paradigm, which has been shown to reflect more than lexical access times. We measured naming times for words in sentences read for meaning. Our findings confirm that lexical access for function words is indeed faster than for content words as predicted by neurolinguistic theory and electrophysiological evidence, but that this difference can be attributed to word predictability (Cloze value) and word familiarity (log frequency). We also show that differences in frequency effect for the two word types holds only for the lower frequency words and not at all for the higher frequency words. We discuss the implications of the results for neurolinguistic theory.