Distinguishing between cognitive explanations of the problem size effect in mental arithmetic via representational similarity analysis of fMRI data

Not all researchers interested in human behavior remain convinced that modern neuroimaging techniques have much to contribute to distinguishing between competing cognitive models for explaining human behavior, especially if one removes reverse inference from the table. Here, we took up this challenge in an attempt to distinguish between two competing accounts of the problem size effect (PSE), a robust finding in investigations of mathematical cognition. The PSE occurs when people solve arithmetic problems and indicates that numerically large problems are solved more slowly and erroneously than small problems. Neurocognitive explanations for the PSE can be categorized into representation-based and process-based views. Behavioral and traditional univariate neural measures have struggled to distinguish between these accounts. By contrast, a representational similarity analysis (RSA) approach with fMRI data provides competing hypotheses that can distinguish between accounts without recourse to reverse inference. To that end, our RSA (but not univariate) results provided clear evidence in favor of the representation-based over the process-based account of the PSE in multiplication; for addition, the results were less clear. Post-hoc similarity analysis distinguished still further between competing representation-based theoretical accounts. Namely, data favored the notion that individual multiplication problems are stored as individual memory traces sensitive to input frequency over a strictly magnitude-based account of memory encoding. Together, these results provide an example of how human neuroimaging evidence can directly inform cognitive-level explanations of a common behavioral phenomenon, the problem size effect. More broadly, these data may expand our understanding of calculation and memory systems in general

Flaunting it on Facebook: Young adults, drinking cultures and the cult of celebrity

Copyright © Antonia Lyons; Tim McCreanor; Fiona Hutton; Ian Goodwin; Helen Moewaka Barnes; Christine Griffin; Kerryellen Vroman; Acushla Dee O’Carroll; Patricia Niland; Lina Samu Print publication available from: http://www.drinkingcultures.info/Young adults in Aotearoa/New Zealand (NZ) regularly engage in heavy drinking episodes with groups of friends within a collective culture of intoxication to ‘have fun’ and ‘be sociable’. This population has also rapidly increased their use of new social networking technologies (e.g. mobile camera/ video phones; Facebook and YouTube) and are said to be obsessed with identity, image and celebrity. This research project explored the ways in which new technologies are being used by a range of young people (and others, including marketers) in drinking practices and drinking cultures in Aotearoa/NZ. It also explored how these technologies impact on young adults’ behaviours and identities, and how this varies across young adults of diverse ethnicities (Maori [indigenous people of NZ], Pasifika [people descended from the Pacific Islands] and Pakeha [people of European descent]), social classes and genders. We collected data from a large and diverse sample of young adults aged 18-25 years employing novel and innovative methodologies across three data collection stages. In total 141 participants took part in 34 friendship focus group discussions (12 Pakeha, 12 Maori and 10 Pasifika groups) while 23 young adults showed and discussed their Facebook pages during an individual interview that involved screencapture software and video recordings. Popular online material regarding drinking alcohol was also collected (via groups, interviews, and web searches), providing a database of 487 links to relevant material (including websites, apps, and games). Critical and in-depth qualitative analyses across these multimodal datasets were undertaken. Key findings demonstrated that social technologies play a crucial role in young adults’ drinking cultures and processes of identity construction. Consuming alcohol to a point of intoxication was a commonplace leisure-time activity for most of the young adult participants, and social network technologies were fully integrated into their drinking cultures. Facebook was employed by all participants and was used before, during and following drinking episodes. Uploading and sharing photos on Facebook was particularly central to young people’s drinking cultures and the ongoing creation of their identities. This involved a great deal of Facebook ‘work’ to ensure appropriate identity displays such as tagging (the addition of explanatory or identifying labels) and untagging photos. Being visible online was crucial for many young adults, and they put significant amounts of time and energy into updating and maintaining Facebook pages, particularly with material regarding drinking practices and events. However this was not consistent across the sample, and our findings revealed nuanced and complex ways in which people from different ethnicities, genders and social classes engaged with drinking cultures and new technologies in different ways, reflecting their positioning within the social structure. Pakeha shared their drinking practices online with relatively little reflection, while Pasifika and Maori participants were more likely to discuss avoiding online displays of drinking and demonstrated greater reflexive self-surveillance. Females spoke of being more aware of normative expectations around gender than males, and described particular forms of online identity displays (e.g. moderated intake, controlled selfdetermination). Participants from upper socio-economic groups expressed less concern than others about both drinking and posting material online. Celebrity culture was actively engaged with, in part at least, as a means of expressing what it is to be a young adult in contemporary society, and reinforcing the need for young people to engage in their own everyday practices of ‘celebritising’ themselves through drinking cultures online. Alcohol companies employed social media to market their products to young people in sophisticated ways that meant the campaigns and actions were rarely perceived as marketing. Online alcohol marketing initiatives were actively appropriated by young people and reproduced within their Facebook pages to present tastes and preferences, facilitate social interaction, construct identities, and more generally develop cultural capital. These commercial activities within the commercial platforms that constitute social networking systems contribute heavily to a general ‘culture of intoxication’ while simultaneously allowing young people to ‘create’ and ‘produce’ themselves online via the sharing of consumption ‘choices’, online interactions and activities

From counting to retrieving: Neural networks underlying alphabet arithmetic learning

This fMRI study aimed at unraveling the neural basis of learning alphabet arithmetic facts, as a proxy of the transition from slow and effortful procedural counting-based processing to fast and effortless processing as it occurs in learning addition arithmetic facts. Neural changes were tracked while participants solved alphabet arithmetic problems in a verification task (e.g., F + 4 = J). Problems were repeated across four learning blocks. Two neural networks with opposed learning-related changes were identified. Activity in a network consisting of basal ganglia and parieto-frontal areas decreased with learning, which is in line with a reduction of the involvement of procedure-based processing. Conversely, activity in a network involving the left angular gyrus and, to a lesser extent, the hippocampus gradually increases with learning, evidencing the gradual involvement of retrieval-based processing. Connectivity analyses gave insight in the functional relationship between the two networks. Despite the opposing learning-related trajectories, it was found that both networks become more integrated. Taking alphabet arithmetic as a proxy for learning arithmetic, the present results have implications for current theories of learning arithmetic facts and can give direction to future developments

Numerical and Non-numerical Predictors of First Graders’ Number-Line Estimation Ability

Children’s ability to map numbers into a spatial context has been shown to be a powerful predictor of math performance. Here, we investigate how three types of cognitive abilities – approximate number processing ability, symbolic number processing ability, and non-numerical cognitive abilities – predict 0–100 number-line estimation performance in first graders. While each type of measure predicts number-line performance when considered individually, when considered together, only symbolic number comparison and non-verbal reasoning predicted unique variance in number-line estimation. Moreover, the relation between symbolic number comparison and number-line ability was stronger for male students than for female students, suggesting potential gender differences in the way boys and girls accomplish mapping numbers into space. These results suggest that number-line estimation ability is largely reflective of the precision with which symbolic magnitudes are represented (at least among boys). Our findings therefore suggest that promoting children’s understanding of symbolic, rather than non-symbolic, numerical magnitudes may help children learn better from number-lines in the classroom

Lectin binding profiles of SSEA-4 enriched, pluripotent human embryonic stem cell surfaces

BACKGROUND: Pluripotent human embryonic stem cells (hESCs) have the potential to form every cell type in the body. These cells must be appropriately characterized prior to differentiation studies or when defining characteristics of the pluripotent state. Some developmentally regulated cell surface antigens identified by monoclonal antibodies in a variety of species and stem cell types have proven to be side chains of membrane glycolipids and glycoproteins. Therefore, to examine hESC surfaces for other potential pluripotent markers, we used a panel of 14 lectins, which were chosen based on their specificity for a variety of carbohydrates and carbohydrate linkages, along with stage specific embryonic antigen-4 (SSEA-4), to determine binding quantitation by flow cytometry and binding localization in adherent colonies by immunocytochemistry. RESULTS: Enriching cells for SSEA-4 expression increased the percentage of SSEA-4 positive cells to 98–99%. Using enriched high SSEA-4-expressing hESCs, we then analyzed the binding percentages of selected lectins and found a large variation in binding percentages ranging from 4% to 99% binding. Lycopersicon (tomato)esculetum lectin (TL), Ricinus communis agglutinin (RCA), and Concanavalin A (Con A) bound to SSEA-4 positive regions of hESCs and with similar binding percentages as SSEA-4. In contrast, we found Dolichos biflorus agglutinin (DBA) and Lotus tetragonolobus lectin (LTL) did not bind to hESCs while Phaseolus vulgaris leuco-agglutinin (PHA-L), Vicia villosa agglutinin (VVA), Ulex europaeus agglutinin (UEA), Phaseolus vulgaris erythro-agglutinin (PHA-E), and Maackia amurensis agglutinin (MAA) bound partially to hESCs. These binding percentages correlated well with immunocytochemistry results. CONCLUSION: Our results provide information about types of carbohydrates and carbohydrate linkages found on pluripotent hESC surfaces. We propose that TL, RCA and Con A may be used as markers that are associated with the pluripotent state of hESCs because binding percentages and binding localization of these lectins are similar to those of SSEA-4. Non-binding lectins, DBA and LTL, may identify differentiated cell types; however, we did not find these lectins to bind to pluripotent SSEA-4 positive hESCs. This work represents a fundamental base to systematically classify pluripotent hESCs, and in future studies these lectins may be used to distinguish differentiated hESC types based on glycan presentation that accompanies differentiation

Effects of engineered silver nanoparticles on the growth and activity of ecologically important microbes

Summary: Currently, little is known about the impact of silver nanoparticles (AgNPs) on ecologically important microorganisms such as ammonia-oxidizing bacteria (AOB). We performed a multi-analytical approach to demonstrate the effects of uncapped nanosilver (uAgNP), capped nanosilver (cAgNP) and Ag2SO4 on the activities of the AOB: Nitrosomonas europaea, Nitrosospira multiformis and Nitrosococcus oceani, and the growth of Escherichia coli and Bacillus subtilis as model bacterial systems in relation to AgNP type and concentration. All Ag treatments caused significant inhibition to the nitrification potential rates (NPRs) of Nitrosomonas europaea (decreased from 34 to cAgNP>uAgNP. In conclusion, AgNPs (especially cAgNPs) and Ag2SO4 adversely affected AOB activities and thus have the potential to severely impact key microbially driven processes such as nitrification in the environment

Can Plants be used as Indicators of the Impacts of Livestock Grazing on Carabid Beetles in Upland Calcareous Grassland

The International Congress for Conservation Biology and European Congress for Conservation Biology (ICCBECCB) is a forum for addressing conservation challenges and for presenting new research and developments in conservation science and practice. The meeting theme, Mission Biodiversity: Choosing new paths for conservation, is a response to indications that many traditional methods for conserving biodiversity have proven unsuccessful. It emphasizes that rapid and ongoing biophysical and societal changes affect the way we do science and practice conservation today