The association of macro- and microstructure of the corpus callosum and language lateralisation

The present study aimed to examine how differences in functional lateralisation of language are related to interindividual variations in interhemispheric connectivity. Utilising an fMRI silent word-generation paradigm, 89 left- and right-handed subjects were subdivided into four lateralisation subgroups. Applying morphological and diffusion-tensor MRI, midsagittal cross-sectional area as well as quantitative measures of molecular diffusion (anisotropy, mean diffusion) of the corpus callosum were determined to assess interhemispheric connectivity. Statistical analyses revealed group differences in molecular diffusion but not in callosal size, which may be interpreted to reflect a stronger and/or faster interhemispheric connection in strongly left-lateralised subjects as compared to moderately left-lateralised, bilateral, or moderately right-lateralised subjects.     

Differences in family functioning in grandparent and parent-headed households in a clinical sample of drug-using African American adolescents

Grandparents play a critical role in African American families, providing support and important leadership functions. Little is known, however, about family functioning in grandparent-headed households with a drug-using adolescent. Such knowledge is particularly salient for researchers and therapists who work with drug-using adolescents and their families. Using a clinical sample of convenience, analyses were conducted to identify similarities and differences in adolescent substance use and behavior problems, family relationships, and family social ecology relationships between African American grandparent-headed (n=12) and parent-headed (n=54) households. Results indicated that adolescents from the 2 household types reported similar levels of problem behaviors, but that grandparents reported less delinquency with peers than did parents. Primary caregivers in grandparent-headed households reported less monitoring and supervision of peers and less within-family conflict. Implications for treatment are discussed.     

Anatomy of a decision: striato-orbitofrontal interactions in reinforcement learning, decision making, and reversal

The authors explore the division of labor between the basal ganglia-dopamine (BG-DA) system and the orbitofrontal cortex (OFC) in decision making. They show that a primitive neural network model of the BG-DA system slowly learns to make decisions on the basis of the relative probability of rewards but is not as sensitive to (a) recency or (b) the value of specific rewards. An augmented model that explores BG-OFC interactions is more successful at estimating the true expected value of decisions and is faster at switching behavior when reinforcement contingencies change. In the augmented model, OFC areas exert top-down control on the BG and premotor areas by representing reinforcement magnitudes in working memory. The model successfully captures patterns of behavior resulting from OFC damage in decision making, reversal learning, and devaluation paradigms and makes additional predictions for the underlying source of these deficits.     

What do children want to know about animals and artifacts? Domain-specific requests for information

Children's questions may reveal a great deal about the characteristics of objects they consider to be conceptually important. Thirty-two preschool children were given opportunities to ask questions about unfamiliar artifacts and animals. The children asked ambiguous questions such as "What is it?" about artifacts and animals alike. However, they were more likely to ask about the functions of artifacts, but about category membership, food choices, and typical locations of animals. They never asked questions about either artifacts or animals that would be considered inappropriate by adults. The results indicate that children hold different expectations about the types of information important for categorizing living and artifact kinds. Young children conceive of artifacts in terms of functions, but conceive of animals in terms of biologically appropriate characteristics. Such results speak to debates about the role of function in children's biological reasoning and to accounts of children's artifact concepts.     

Neural blackboard architectures of combinatorial structures in cognition

Human cognition is unique in the way in which it relies on combinatorial (or compositional) structures. Language provides ample evidence for the existence of combinatorial structures, but they can also be found in visual cognition. To understand the neural basis of human cognition, it is therefore essential to understand how combinatorial structures can be instantiated in neural terms. In his recent book on the foundations of language, Jackendoff described four fundamental problems for a neural instantiation of combinatorial structures: the massiveness of the binding problem, the problem of 2, the problem of variables, and the transformation of combinatorial structures from working memory to long-term memory. This paper aims to show that these problems can be solved by means of neural "blackboard" architectures. For this purpose, a neural blackboard architecture for sentence structure is presented. In this architecture, neural structures that encode for words are temporarily bound in a manner that preserves the structure of the sentence. It is shown that the architecture solves the four problems presented by Jackendoff. The ability of the architecture to instantiate sentence structures is illustrated with examples of sentence complexity observed in human language performance. Similarities exist between the architecture for sentence structure and blackboard architectures for combinatorial structures in visual cognition, derived from the structure of the visual cortex. These architectures are briefly discussed, together with an example of a combinatorial structure in which the blackboard architectures for language and vision are combined. In this way, the architecture for language is grounded in perception. Perspectives and potential developments of the architectures are discussed.     

A motion capture library for the study of identity, gender, and emotion perception from biological motion

We present the methods that were used in capturing a library of human movements for use in computer-animated displays of human movement. The library is an attempt to systematically tap into and represent the wide range of personal properties, such as identity, gender, and emotion, that are available in a person's movements. The movements from a total of 30 nonprofessional actors (15 of them female) were captured while they performed walking, knocking, lifting, and throwing actions, as well as their combination in angry, happy, neutral, and sad affective styles. From the raw motion capture data, a library of 4,080 movements was obtained, using techniques based on Character Studio (plug-ins for 3D Studio MAX, AutoDesk, Inc.), MATLAB The MathWorks, Inc.), or a combination of these two. For the knocking, lifting, and throwing actions, 10 repetitions of the simple action unit were obtained for each affect, and for the other actions, two longer movement recordings were obtained for each affect. We discuss the potential use of the library for computational and behavioral analyses of movement variability, of human character animation, and of how gender, emotion, and identity are encoded and decoded from human movement.     

What makes multiplication facts difficult. Problem size or neighborhood consistency?

Two current models of arithmetic fact retrieval, the network interference theory (NIT; Campbell, 1995) and the interacting neighbors (IN) model (Verguts & Fias, 2005a), predict that errors in simple multiplication should be more probable, if they include the same digit as the correct result (i.e., if they are "consistent," compared with "inconsistent" errors). In a reanalysis of error data originally reported by Campbell (1997), we provide first empirical evidence for this prediction. Furthermore, these results support the notion of different quantity representations for decades and units as proposed by Nuerk, Weger, and Willmes (2001). However, the NIT and IN-model differ in their explanations of the problem-size effect, a hallmark finding robustly observed in arithmetic fact retrieval. Only the IN-model predicts that a correct answer's neighborhood consistency can fully account for the problem-size effect, which was confirmed in our analysis.     

Identity status measurement across contexts: variations in measurement structure and mean levels among White American, Hispanic American, and Swedish emerging adults

We conducted this study to examine measurement equivalence and mean differences in identity status across 3 ethnic/cultural contexts: White American, Hispanic American, and Swedish. We used the Extended Objective Measure of Ego Identity Status II (EOM-EIS-II; Bennion & Adams, 1986), a commonly used instrument in the identity status literature. We conducted analyses to ascertain the extent to which the EOM-EIS-II functioned equivalently in 3 ethnically/culturally different samples. The internal structure of the measure was consistent across contexts. When we statistically controlled effects of age and gender, mean differences tended to be largely cross-cultural at the observed level of analysis but to be both cross-ethnic and cross-cultural at the latent level of analysis. This divergence in findings was found despite the limited age range represented in each of the samples. We therefore concluded that measurement error may have played a role in these differences and that data gathered using the EOM-EIS-II should be analyzed using latent variable methods. We discuss results in terms of using the EOM-EIS-II with diverse populations.     

Return of fear in a human differential conditioning paradigm caused by a stimulus change after extinction

In a human fear conditioning experiment, 32 participants were trained in a differential conditioning procedure with geometrical shapes as CS+ and CS- (four presentations each), and an electric shock as US. Measures of conditioned responding were skin conductance response (SCR) and retrospective US-expectancy ratings. For half of the participants (Generalization Group, GG), the subsequent extinction phase consisted of four nonreinforced presentations of generalization stimuli (GS+ and GS-). Participants from the Extinction control Group received an equal amount of nonreinforced presentations of the CSs. Finally, all participants were tested with the original CSs. The results from both measures clearly show an increase in the size of the discrimination upon the stimulus change after extinction in the GG. Because this pattern is not observed in the Extinction control Group, extinction performance appears to be somehow restricted to the perceptual characteristics of the extinction stimulus. Interestingly, the size of the conditioned SCR discrimination in the GG is not influenced by the stimulus change after acquisition. This observation points to a differential impact of stimulus change after acquisition vs. extinction treatment. The findings are discussed from the theoretical perspective of renewal and the clinical perspective of Return of Fear.