Imitation fidelity increases with age in boys, but not in girls: An intriguing finding in a cohort of children aged 3 to 6 years.

Imitation that entails faithful reproduction of demonstrated behavior by reenacting a sequence of actions accurately is a fast and efficient way to acquire new skills as well as to conform to social norms. Previous studies reported that both culture and gender might impinge on young children's fidelity of imitation. We analyzed the imitative behavior of 87 children whose ages ranged from 3 to 6 years. An instrumental task was administered that offered partial (opaque apparatus) or total (transparent apparatus) information about causal connection between the demonstrated actions and their effect in achieving a desired reward. Imitative fidelity (imitating the actions that were demonstrated by an adult model yet were unnecessary for achieving the instrumental goal) increased as a function of age in boys, whereas no differences were found in girls. This lack of increase in girls can be ascribed to their displaying higher degrees of imitation fidelity at an earlier age.

Linguistic, concept and symbolic composition in adults with minimal receptive vocabulary.

In this paper, we examine some basic linguistic abilities in a small sample of adults with minimal receptive vocabulary, whose receptive mental verbal age ranges from 1;2 to 3;10. In particular, we examine whether the participants in our study understand noun phrases consisting of a noun modified by an adjective. We use stimuli that they can recognise by name. Except for one participant, we find that, while all of them understand the noun and adjective in isolation, none seems to understand these noun phrases, which means that they seem to not do linguistic composition. In order to test whether the difficulty is linguistic or conceptual, we ran two other studies, one on concept composition, and the other on iconic symbolic composition (composition of pictograms). Results suggest that linguistic composition is particularly difficult in this population, and that vocabulary breadth may not predict compositional abilities.

Are monkeys intuitive Aristotelians? Associations between target size and vertical target position in long-tailed macaques.

Different hypotheses have been put forward to explain the interaction between size perception and spatial position. To explore the evolutionary roots of these phenomena, we tested long-tailed macaques' performance in a two-choice discrimination task on a touchscreen and contrasted two hypotheses. First, a hierarchy association in which large objects are associated with top positions, due to a link between power, dominance and importance with top position. Second, a naive Aristotelian association in which large objects are associated with bottom positions, due to the experience that larger objects are heavier and thus more likely to be found at the bottom. Irrespective of training regime (positively reinforcing the small (Touch-Small) or large (Touch-Large) stimulus), the monkeys had a bias to touch the bottom compared to the top location. Individuals in the Touch-Small group took significantly longer to acquire the task, but subsequently made fewer mistakes. When presented with two stimuli of equal medium size, the Touch-Large group had a clear bias to touch the lower stimulus, while the Touch-Small group touched both locations at equal rates. Our findings point to an innate bias towards larger stimuli and a natural preference for the lower position, while the extent of interaction between size and position depends on executive control requirements of a task.