Peer tutoring of computer programming increases exploratory behavior in children.

There is growing interest in teaching computer science and programming skills in schools. Here we investigated the efficacy of peer tutoring, which is known to be a useful educational resource in other domains but never before has been examined in such a core aspect of applied logical thinking in children. We compared (a) how children (N = 42, age range = 7 years 1 month to 8 years 4 months) learn computer programming from an adult versus learning from a peer and (b) the effect of teaching a peer versus simply revising what has been learned. Our results indicate that children taught by a peer showed comparable overall performance-a combination of accuracy and response times-to their classmates taught by an adult. However, there was a speed-accuracy trade-off, and peer-taught children showed more exploratory behavior, with shorter response times at the expense of lower accuracy. In contrast, no tutor effects (i.e., resulting from teaching a peer) were found. Thus, our results provide empirical evidence in support of peer tutoring as a way to help teach computer programming to children. This could contribute to the promotion of a widespread understanding of how computers operate and how to shape them, which is essential to our values of democracy, plurality, and freedom.

Language, gesture, and judgment: Children's paths to abstract geometry.

As infants, children are sensitive to geometry when recognizing objects or navigating through rooms; however, explicit knowledge of geometry develops slowly and may be unstable even in adults. How can geometric concepts be both so accessible and so elusive? To examine how implicit and explicit geometric concepts develop, the current study assessed, in 132 children (3-8 years old) while they played a simple geometric judgment task, three distinctive channels: children's choices during the game as well as the language and gestures they used to justify and accompany their choices. Results showed that, for certain geometric properties, children chose the correct card even if they could not express with words (or gestures) why they had made this choice. Furthermore, other geometric concepts were expressed and supported by gestures prior to their articulation in either choices or speech. These findings reveal that gestures and behavioral choices may reflect implicit knowledge and serve as a foundation for the development of geometric reasoning. Altogether, our results suggest that language alone might not be enough for expressing and organizing geometric concepts and that children pursue multiple paths to overcome its limitations, a finding with potential implications for primary education in mathematics.

Neglect in human communication: quantifying the cost of cell-phone interruptions in face to face dialogs.

There is a prevailing belief that interruptions using cellular phones during face to face interactions may affect severely how people relate and perceive each other. We set out to determine this cost quantitatively through an experiment performed in dyads, in a large audience in a TEDx event. One of the two participants (the speaker) narrates a story vividly. The listener is asked to deliberately ignore the speaker during part of the story (for instance, attending to their cell-phone). The speaker is not aware of this treatment. We show that total amount of attention is the major factor driving subjective beliefs about the story and the conversational partner. The effects are mostly independent on how attention is distributed in time. All social parameters of human communication are affected by attention time with a sole exception: the perceived emotion of the story. Interruptions during day-to-day communication between peers are extremely frequent. Our data should provide a note of caution, by indicating that they have a major effect on the perception people have about what they say (whether it is interesting or not . . .) and about the virtues of the people around them.

Quercetin antagonism of GABAAρ1 receptors is prevented by ascorbic acid through a redox-independent mechanism.

Quercetin is a natural flavonoid widely distributed in plants that acts as a neuroprotective agent and modulates the activity of different synaptic receptors and ion channels, including the ionotropic GABA receptors. GABA(Aρ1) receptors were shown to be antagonized by quercetin, but the mechanisms underlying these antagonistic actions are still unknown. We have analyzed here if the antagonistic action produced by quercetin on GABA(Aρ1) receptors was related to its redox activity or due to alternative mechanism/s. Homomeric GABA(Aρ1) receptors were expressed in frog oocytes and GABA-evoked responses electrophysiologically recorded. Quercetin effects on GABA(Aρ1) receptors were examined in the absence or presence of ascorbic acid. Chemical protection of cysteines by selective sulfhydryl reagents and site directed mutagenesis experiments were also used to determine ρ1 subunit residues involved in quercetin actions. Quercetin antagonized GABA(Aρ1) receptor responses in a dose-dependent, fast and reversible manner. Quercetin inhibition was prevented in the presence of ascorbic acid, but not by thiol reagents that modify the extracellular Cys-loop of these receptors. H141, an aminoacidic residue located near to the ρ1 subunit GABA binding site, was involved in the allosteric modulation of GABA(Aρ1) receptors by several agents including ascorbic acid. Quercetin similarly antagonized GABA-evoked responses mediated by mutant (H141D)GABA(Aρ1) and wild-type receptors, but prevention exerted by ascorbic acid on quercetin effects was impaired in mutant receptors. Taken together the present results suggest that quercetin antagonistic actions on GABA(Aρ1) receptors are mediated through a redox-independent allosteric mechanism.

Age and gender dependent development of Theory of Mind in 6- to 8-years old children.

The ability to attribute different mental states to distinct individuals, or Theory of Mind (ToM), is widely believed to be developed mostly during preschool years. How different factors such as gender, number of siblings, or coarse personality traits affect this development is not entirely agreed upon. Here, we introduce a computerized version of the scaled ToM suite of tasks introduced by Wellman and Liu (2004), which allows us to meaningfully test ToM development on children 6 to 8-years old. We find that kids this age are still not entirely proficient in all ToM tasks, and continue to show a progression of performance with age. By testing this new age range, too, we are able to observe a significant advantage of girls over boys in ToM performance. Other factors such as number of siblings, birth order, and coarse personality traits show no significant relation with the ToM task results. Finally, we introduce a novel way to quantify the scaling property of the suite involving a sequence of set inclusions on one hand and a comparison between specially tailored sets of logistic models on the other. These measures confirm the validity of the scale in the 6- to 8-years old range.

Allosteric modulation of retinal GABA receptors by ascorbic acid.

Ionotropic GABA receptors (GABA(A) and GABA(C)) belong to the Cys-loop receptor family of ligand-gated ion channels. GABA(C) receptors are highly expressed in the retina, mainly localized at the axon terminals of bipolar cells. Ascorbic acid, an endogenous redox agent, modulates the function of diverse proteins, and basal levels of ascorbic acid in the retina are very high. However, the effect of ascorbic acid on retinal GABA receptors has not been studied. Here we show that the function of GABA(C) and GABA(A) receptors is regulated by ascorbic acid. Patch-clamp recordings from bipolar cell terminals in goldfish retinal slices revealed that GABA(C) receptor-mediated currents activated by tonic background levels of extracellular GABA, and GABA(C) currents elicited by local GABA puffs, are both significantly enhanced by ascorbic acid. In addition, a significant rundown of GABA puff-evoked currents was observed in the absence of ascorbic acid. GABA-evoked Cl(-) currents mediated by homomeric ρ(1) GABA(C) receptors expressed in Xenopus laevis oocytes were also potentiated by ascorbic acid in a concentration-dependent, stereo-specific, reversible, and voltage-independent manner. Studies involving the chemical modification of sulfhydryl groups showed that the two Cys-loop cysteines and histidine 141, all located in the ρ(1) subunit extracellular domain, each play a key role in the modulation of GABA(C) receptors by ascorbic acid. Additionally, we show that retinal GABA(A) IPSCs and heterologously expressed GABA(A) receptor currents are similarly augmented by ascorbic acid. Our results suggest that ascorbic acid may act as an endogenous agent capable of potentiating GABAergic neurotransmission in the CNS.

Redox modulation of homomeric rho1 GABA receptors.

The activity of many receptors and ion channels in the nervous system can be regulated by redox-dependent mechanisms. Native and recombinant GABA(A) receptors are modulated by endogenous and pharmacological redox agents. However, the sensitivity of GABA(C) receptors to redox modulation has not been demonstrated. We studied the actions of different reducing and oxidizing agents on human homomeric GABArho(1) receptors expressed in Xenopus laevis oocytes. The reducing agents dithiothreitol (2 mM) and N-acetyl-L-cysteine (1 mM) potentiated GABA-evoked Cl(-) currents recorded by two-electrode voltage-clamp, while the oxidants 5-5'-dithiobis-2-nitrobenzoic acid (500 microM) and oxidized dithiothreitol (2 mM) caused inhibition. The endogenous antioxidant glutathione (5 mM) also enhanced GABArho(1) receptor-mediated currents while its oxidized form GSSG (3 mM) had inhibitory effects. All the effects were rapid and easily reversible. Redox modulation of GABArho(1) receptors was strongly dependent on the GABA concentration; dose-response curves for GABA were shifted to the left in the presence of reducing agents, whereas oxidizing agents produced the opposite effect, without changes in the maximal response to GABA and in the Hill coefficient. Our results demonstrate that, similarly to GABA(A) receptors and other members of the cys-loop receptor superfamily, GABA(C) receptors are subjected to redox modulation.