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Recent reviews have highlighted the tendency in the comparative literature to make claims about species' relative evolutionarily adaptive histories based on studies comparing different species tested with procedurally and methodologically different protocols. One particularly contentious area is the use of the object-choice task, used to measure an individual's ability to use referential cues, which is a core attribute of joint attention. We tested human children with versions of the object-choice task that have been previously used with dogs and nonhuman primates to see if manipulating the setup would lead to behavioral changes. In Study 1, we compared the responses of 18-month-olds and 36-month-olds when tested with and without a barrier. The presence of a barrier between the child and the reward did not suppress performance but did elicit more communicative behavior. Moreover, the barrier had a greater facilitating effect on the younger children, who displayed more communicative behavior in comparison with older children, who more frequently reached through the barrier in acts of direct prehension. In Study 2, we compared the behavior of 36-month-olds when the reward was within reaching distance (proximal) and when it was out of reach (distal). The children used index-finger points significantly more in the distal condition and grabbed more in the proximal condition, showing that they were making spatial judgments about the accessibility of the reward rather than just grabbing per se. We discuss the implications of these within-species differences in behavioral responses for cross-species comparisons. [ABSTRACT FROM AUTHOR]

Although an abundant literature documents preliterate children's word learning success from shared storybook reading, a full synthesis of the factors which moderate these word learning effects has been largely neglected. This meta-analysis included 38 studies with 2.455 children, reflecting 110 effect sizes, investigating how reading styles, story repetitions, tokens and related factors moderate children's word comprehension, while adjusting for the number of target words. Dialogic reading styles, tokens, and the number of words tested all moderated word learning effects. Children's age, who read the story, and time between story and test were not moderators. We identify story repetition and word types as topics which merit further research. These results provide information to guide researchers and educators alike to the factors with the greatest impact on improving word learning from shared storybook reading. [ABSTRACT FROM AUTHOR]

We investigated how the visibility of targets influenced the type of point used to provide directions. In Study 1, we asked 605 passersby in three localities for directions to well-known local landmarks. When that landmark was in plain view behind the requester, most respondents pointed with their index fingers, and few respondents pointed more than once. In contrast, when the landmark was not in view, respondents pointed initially with their index fingers, but often elaborated with a whole-hand point. In Study 2, we covertly filmed the responses from 157 passersby we approached for directions, capturing both verbal and gestural responses. As in Study 1, few respondents produced more than one gesture when the target was in plain view and initial points were most likely to be index finger points. Thus, in a Western geographical context in which pointing with the index finger is the dominant form of pointing, a slight change in circumstances elicited a preference for pointing with the whole hand when it was the second or third manual gesture in a sequence. [ABSTRACT FROM AUTHOR]