Changing minds: Children's inferences about third party belief revision.

By the age of 5, children explicitly represent that agents can have both true and false beliefs based on epistemic access to information (e.g., Wellman, Cross, & Watson, 2001). Children also begin to understand that agents can view identical evidence and draw different inferences from it (e.g., Carpendale & Chandler, 1996). However, much less is known about when, and under what conditions, children expect other agents to change their minds. Here, inspired by formal ideal observer models of learning, we investigate children's expectations of the dynamics that underlie third parties' belief revision. We introduce an agent who has prior beliefs about the location of a population of toys and then observes evidence that, from an ideal observer perspective, either does, or does not justify revising those beliefs. We show that children's inferences on behalf of third parties are consistent with the ideal observer perspective, but not with a number of alternative possibilities, including that children expect other agents to be influenced only by their prior beliefs, only by the sampling process, or only by the observed data. Rather, children integrate all three factors in determining how and when agents will update their beliefs from evidence.

Gesture Helps, Only If You Need It: Inhibiting Gesture Reduces Tip-of-the-Tongue Resolution for Those With Weak Short-Term Memory.

People frequently gesture when a word is on the tip of their tongue (TOT), yet research is mixed as to whether and why gesture aids lexical retrieval. We tested three accounts: the lexical retrieval hypothesis, which predicts that semantically related gestures facilitate successful lexical retrieval; the cognitive load account, which predicts that matching gestures facilitate lexical retrieval only when retrieval is hard, as in the case of a TOT; and the motor movement account, which predicts that any motor movements should support lexical retrieval. In Experiment 1 (a between-subjects study; N = 90), gesture inhibition, but not neck inhibition, affected TOT resolution but not overall lexical retrieval; participants in the gesture-inhibited condition resolved fewer TOTs than participants who were allowed to gesture. When participants could gesture, they produced more representational gestures during resolved than unresolved TOTs, a pattern not observed for meaningless motor movements (e.g., beats). However, the effect of gesture inhibition on TOT resolution was not uniform; some participants resolved many TOTs, while others struggled. In Experiment 2 (a within-subjects study; N = 34), the effect of gesture inhibition was traced to individual differences in verbal, not spatial short-term memory (STM) span; those with weaker verbal STM resolved fewer TOTs when unable to gesture. This relationship between verbal STM and TOT resolution was not observed when participants were allowed to gesture. Taken together, these results fit the cognitive load account; when lexical retrieval is hard, gesture effectively reduces the cognitive load of TOT resolution for those who find the task especially taxing.

Children's exploratory play tracks the discriminability of hypotheses.

Effective curiosity-driven learning requires recognizing that the value of evidence for testing hypotheses depends on what other hypotheses are under consideration. Do we intuitively represent the discriminability of hypotheses? Here we show children alternative hypotheses for the contents of a box and then shake the box (or allow children to shake it themselves) so they can hear the sound of the contents. We find that children are able to compare the evidence they hear with imagined evidence they do not hear but might have heard under alternative hypotheses. Children (N = 160; mean: 5 years and 4 months) prefer easier discriminations (Experiments 1-3) and explore longer given harder ones (Experiments 4-7). Across 16 contrasts, children's exploration time quantitatively tracks the discriminability of heard evidence from an unheard alternative. The results are consistent with the idea that children have an "intuitive psychophysics": children represent their own perceptual abilities and explore longer when hypotheses are harder to distinguish.

Reduced neural selectivity for mental states in deaf children with delayed exposure to sign language.

Language provides a rich source of information about other people's thoughts and feelings. Consequently, delayed access to language may influence conceptual development in Theory of Mind (ToM). We use functional magnetic resonance imaging and behavioral tasks to study ToM development in child (n = 33, 4-12 years old) and adult (n = 36) fluent signers of American Sign Language (ASL), and characterize neural ToM responses during ASL and movie-viewing tasks. Participants include deaf children whose first exposure to ASL was delayed up to 7 years (n = 12). Neural responses to ToM stories (specifically, selectivity of the right temporo-parietal junction) in these children resembles responses previously observed in young children, who have similar linguistic experience, rather than those in age-matched native-signing children, who have similar biological maturation. Early linguistic experience may facilitate ToM development, via the development of a selective brain region for ToM.

Refining intra-protein contact prediction by graph analysis.

BACKGROUND: Accurate prediction of intra-protein residue contacts from sequence information will allow the prediction of protein structures. Basic predictions of such specific contacts can be further refined by jointly analyzing predicted contacts, and by adding information on the relative positions of contacts in the protein primary sequence. RESULTS: We introduce a method for graph analysis refinement of intra-protein contacts, termed GARP. Our previously presented intra-contact prediction method by means of pair-to-pair substitution matrix (P2PConPred) was used to test the GARP method. In our approach, the top contact predictions obtained by a basic prediction method were used as edges to create a weighted graph. The edges were scored by a mutual clustering coefficient that identifies highly connected graph regions, and by the density of edges between the sequence regions of the edge nodes. A test set of 57 proteins with known structures was used to determine contacts. GARP improves the accuracy of the P2PConPred basic prediction method in whole proteins from 12% to 18%. CONCLUSION: Using a simple approach we increased the contact prediction accuracy of a basic method by 1.5 times. Our graph approach is simple to implement, can be used with various basic prediction methods, and can provide input for further downstream analyses.

"I use it when I see it": The role of development and experience in Deaf and hearing children's understanding of iconic gesture.

Iconicity is prevalent in gesture and in sign languages, yet the degree to which children recognize and leverage iconicity for early language learning is unclear. In Experiment 1 of the current study, we presented sign-naïve 3-, 4- and 5-year-olds (n=87) with iconic shape gestures and no additional scaffolding to ask whether children can spontaneously map iconic gestures to their referents. Four- and five-year-olds, but not three-year-olds, recognized the referents of iconic shape gestures above chance. Experiment 2 asked whether preschoolers (n=93) show an advantage in fast-mapping iconic gestures compared to arbitrary ones. We found that iconicity played a significant role in supporting 4- and 5-year-olds' ability to learn new gestures presented in an explicit pedagogical context, and a lesser role in 3-year-olds' learning. Using similar tasks in Experiment 3, we found that Deaf preschoolers (n=41) exposed to American Sign Language showed a similar pattern of recognition and learning but starting at an earlier age, suggesting that learning a language with rich iconicity may lead to earlier use of iconicity. These results suggest that sensitivity to iconicity is shaped by experience, and while not fundamental to the earliest stages of language development, is a useful tool once children unlock these form-meaning relationships.

Moral alchemy: How love changes norms.

We discuss a process by which non-moral concerns (that is concerns agreed to be non-moral within a particular cultural context) can take on moral content. We refer to this phenomenon as moral alchemy and suggest that it arises because moral obligations of care entail recursively valuing loved ones' values, thus allowing propositions with no moral weight in themselves to become morally charged. Within this framework, we predict that when people believe a loved one cares about a behavior more than they do themselves, the moral imperative to care about the loved one's interests will raise the value of that behavior, such that people will be more likely to infer that third parties will see the behavior as wrong (Experiment 1) and the behavior itself as more morally important (Experiment 2) than when the same behaviors are considered outside the context of a caring relationship. The current study confirmed these predictions.