Splenium development and early spoken language in human infants

The association between developmental trajectories of language‐related white matter fiber pathways from 6 to 24 months of age and individual differences in language production at 24 months of age was investigated. The splenium of the corpus callosum, a fiber pathway projecting through the posterior hub of the default mode network to occipital visual areas, was examined as well as pathways implicated in language function in the mature brain, including the arcuate fasciculi, uncinate fasciculi, and inferior longitudinal fasciculi. The hypothesis that the development of neural circuitry supporting domain‐general orienting skills would relate to later language performance was tested in a large sample of typically developing infants. The present study included 77 infants with diffusion weighted MRI scans at 6, 12 and 24 months and language assessment at 24 months. The rate of change in splenium development varied significantly as a function of language production, such that children with greater change in fractional anisotropy (FA) from 6 to 24 months produced more words at 24 months. Contrary to findings from older children and adults, significant associations between language production and FA in the arcuate, uncinate, or left inferior longitudinal fasciculi were not observed. The current study highlights the importance of tracing brain development trajectories from infancy to fully elucidate emerging brain–behavior associations while also emphasizing the role of the splenium as a key node in the structural network that supports the acquisition of spoken language.     

Considering Development in Developmental Disorders

Various theorists have argued for the importance of a developmental approach to studying typical development (Karmiloff-Smith, 1998; Lerner, 1996; Lerner & Hood, 1986; Masten & Cicchetti, 2010; Overton, 2014; Overton & Lerner, 2012, 2014), and there are reasons to believe that this issue is even more critical to the study of atypical development (Thomas, 2016; Thomas et al., 2009). In this article, we bring together perspectives from a variety of theorists to outline the importance of conceptualizing both typical and atypical development as a not-necessarily-linear, interconnected, and multifaceted set of individual trajectories embedded in real-world contexts (Karmiloff-Smith, 1998; Masten & Cicchetti, 2010; Overton & Lerner, 2012). Using examples from studies of atypical brain and behavior, we describe 6 lenses that can be applied to developmental research.     

The role of attention and relatedness in emotionally enhanced memory

Examining the positive and negative pictures separately revealed that emotionally enhanced memory (EEM) for positive pictures was mediated by attention, with no significant influence of emotional arousal, whereas the reverse was true of negative pictures. Consistent with this finding, in Experiment 2 EEM for negative pictures was found even when task emphasis was manipulated so that equivalent attention was allocated to negative and neutral pictures. The results show that attention and semantic relatedness contribute to EEM, with the extent varying with emotional valence. Negative emotion can influence memory independently of these 2 factors.     

Reevaluating split-fovea processing in word recognition: Hemispheric dominance, retinal location, and the word-nonword effect

Many studies have claimed that hemispheric projections are split precisely at the foveal midline and so hemispheric asymmetry affects word recognition right up to the point of fixation. To investigate this claim, four-letter words and nonwords were presented to the left or right of fixation, either close to fixation in foveal vision or farther from fixation in extrafoveal vision. Presentation accuracy was controlled using an eyetracker linked to a fixation-contingent display. Words presented foveally produced identical performance on each side of fixation, but words presented extrafoveally showed a clear left-hemisphere (LH) advantage. Nonwords produced no evidence of hemispheric asymmetry in any location. Foveal stimuli also produced an identical word-nonword effect on each side of fixation, whereas extrafoveal stimuli produced a word-nonword effect only for LH (not right-hemisphere) displays. These findings indicate that functional unilateral projections to contralateral hemispheres exist in extrafoveal locations but provide no evidence of a functional division in hemispheric processing at fixation.     

The influence of only and even on online semantic interpretation

Focus particles such as only and even indicate that the focused element(s) in a sentence should be contrasted with a set of contextually defined alternatives. Only indicates that properties assigned to the focus set are not shared by elements of the alternative set, whereas even indicates that the focus and alternative sets share the properties mentioned in the sentence. Even has the additional function of marking the focused element as being low on a scale of alternatives ranked in terms of likelihood, thereby signaling that what is being described is somewhat surprising. Using eyetracking, we demonstrate that contrast information associated with only and even is rapidly processed online, with effects for even being delayed, as compared with only (Experiment 1). This difference in time course was not driven by the underlying semantics of the sentence without the focus particle (Experiment 2) but was probably due to even’s more complex semantic function.     

Liars are perceived as more credible than truth-tellers who recall a repeated event

Recurring forms of abuse like domestic violence are unfortunately common. When an individual makes an allegation about their experience, however, there is rarely additional evidence to corroborate their claim. The veracity of the allegation is thus likely to be a central concern in subsequent proceedings. This experiment explored evaluator's perceptions of adults who were lying, or truthfully recalling a repeated event. In this experiment, participants observed a filmed interview of a speaker recalling an event they had experienced once, or a speaker recalling one instance of an event that they had experienced multiple times. Alternatively, some participants viewed an interview of a speaker who was lying about the event. Repeated-event speakers were perceived as less credible than both single-event speakers and liars. It is important that future research investigates ways to reduce the negative effect that the nature of memory for a repeated event has upon speakers' perceived credibility.     

Arab Youth in Canada: Acculturation,Enculturation, Social Support,and Life Satisfaction

Results from 98 Arab youth in Canada showed that having a positive Arab culture orientation was related to greater family life satisfaction with family social support as a mediator. A positive European Canadian orientation was related to greater school life satisfaction, but this relation was not mediated by friend social support. Implications for the processes of enculturation and acculturation are discussed. Los resultados obtenidos de 98 jóvenes Árabes en Canadá mostraron que tener una orientación cultural Árabe positiva estaba relacionado con una mayor satisfacción sobre la vida en familia, con el apoyo social familiar como mediador. Tener una orientación Eurocanadiense positiva estaba relacionado con una mayor satisfacción en la vida escolar, pero esta relación no estaba mediada por el apoyo social de los amigos. Se discuten las implicaciones para los procesos de inculturación y aculturación.     

Response Inhibition and ADHD Traits: Correlates and Heritability in a Community Sample

Endophenotypes or intermediate phenotypes are of great interest in neuropsychiatric genetics because of their potential for facilitating gene discovery. We evaluated response inhibition, latency and variability measures derived from the stop task as endophenotypes of ADHD by testing whether they were related to ADHD traits in the general population, heritable and shared genetic risk with ADHD traits. Participants were 16,099 children and adolescents, ages 6 to 18 years who visited a local science center. We measured ADHD traits using the Strengths and Weaknesses of ADHD-symptoms and Normal-Behavior (SWAN) rating scale and performance on the stop signal task (SST)—response inhibition (SSRT), response latency (GoRT), and response variability (GoRTSD). Regression analysis was used to assess the relationship of cognitive measures and ADHD traits while controlling for family, age, sex, ethnicity, socioeconomic status and treatment status. Heritability of ADHD and cognitive traits was estimated using SOLAR in 7,483 siblings from 3,507 families that included multiple siblings. Bivariate relationships between pairs of variables were examined. Individuals with greater ADHD trait scores had worse response inhibition, slower response latency, and greater variability. Younger participants and girls had inferior performance although the gender effects were minimal and evident in youngest participants. Inhibition, latency, variability, total ADHD traits, inattention and hyperactivity-impulsivity scores were significantly heritable. ADHD traits and inhibition, but not latency or variability were coheritable. In the largest study in the general population, we found support for the validity of response inhibition as an endophenotype of ADHD.     

Reading direction and the central perceptual span: Evidence from Arabic and English

In English and other alphabetic languages read from left to right, useful information acquired during each fixational pause is generally reported to extend much further to the right of each fixation than to the left. However, the asymmetry of the perceptual span for alphabetic languages read in the opposite direction (i.e., from right to left) has received very little attention in empirical research. Accordingly, we investigated the perceptual span for Arabic, which is one of the world’s most widely read languages and is read from right to left, using a gaze-contingent window paradigm in which a region of text was displayed normally around each point of fixation, while text outside this region was obscured. Skilled Arabic readers who were bilingual in Arabic and English read Arabic and English sentences while a window of normal text extended symmetrically 0.5^o to the left and right of fixation or asymmetrically, by increasing this window to 1.5^o or 2.5^o to either the left or the right. When English was read, performance across window conditions was superior when windows extended rightward. However, when Arabic was read, performance was superior when windows extended leftward and was essentially the reverse of that observed for English. These findings show for the first time that a leftward asymmetry in the central perceptual span occurs when Arabic is read and, for the first time in over 30 years, provide a new indication that the perceptual span for alphabetic languages is modified by the overall direction of reading.     

Out of sight, out of mind: the rarity of assessing and reporting participants' visual abilities when studying perception of linguistic stimuli

Variations in visual abilities are widespread in the adult population and have profound effects on processing linguistic stimuli (text, words, letters). However, a review of articles (1442) investigating the processing of visually presented linguistic stimuli by non-clinical adult participants, published in 2000-2010 in five leading journals (Journal of Experimental Psychology: Human Perception and Performance; Journal of Experimental Psychology: Learning, Memory, and Cognition; Memory & Cognition; Perception & Psychophysics/Attention, Perception, & Psychophysics; and Perception), showed that the majority of articles (73.5%) made no mention of participants' visual abilities (62.1%) or relied merely on participants' self-report (11.4%). 25.2% reported participants' visual abilities with no assessment, and only 1.2% reported participants' visual abilities following objective assessment; the highest percentage of articles within this laudable minority was in Perception. The indications are that objective visual assessments in studies of visually presented linguistic stimuli are rare and greater use would facilitate better understanding of the visuo-cognitive processes involved.