7, p   = .0065, ηp2=.54. When the branches could be used to support the discrimination of sets of 5 vs. 6 puppets, children searched longer in the box when the last puppet was missing than when all puppets had already been retrieved. In contrast, they failed to solve the task when the correspondence between branches and puppets did not provide any useful information. Because all children were screened for knowledge of large number words using the diagnostic give-N task, and only those who failed this test were included in the experiment, the findings of Experiment 1 provide Selleckchem FK228 evidence that children

can take advantage of one-to-one correspondence cues to make exact discriminations between large numbers of objects, before they learn symbols for large exact numbers. These findings raise the question BLU9931 supplier of whether children can make a further inference about one-to-one mappings: that such mappings are disrupted by the addition or the subtraction of one object. Experiment 2 addressed this question. Furthermore, we sought to obtain more data on the 11-branch condition, where branches were too numerous to support discrimination of 5 vs. 6 puppets; these new data would increase our statistical power and enable us to test whether subset-knowers

could ever succeed in reconstructing large sets of objects, even without support from one-to-one correspondence cues. The full set of 11-branch results will be presented as Experiment 5, after the results of the experiments presenting informative one-to-one correspondence cues. Experiment 2 used the method of Experiment 1 to investigate Fossariinae whether subset-knowers could use one-to-one correspondence cues to reconstruct the exact number of objects in a set, after an addition or a subtraction of one item. As in Experiment 1, children first viewed sets of 5 or 6 puppets arranged on a tree with 6 branches. While the puppets were in the box, an event occurred that resulted in the addition or subtraction of either one puppet or one branch. If children could successfully take into account

these additions and subtractions, they should search longer for sets containing 6 puppets at the end of the transformation event. If instead children disregarded the effects of the additions and subtractions, they should search longer on trials starting with as many puppets as branches, as in Experiment 1. Finally, it was possible that children might be uncertain about the effects of the additions and subtractions, in which case they might search equally across trials. Participants were 24 subset-knowers (8 female, mean age 34.15 months, 32:15–35:26). All training and testing was as in Experiment 1, except that in the experimental trials, an additional event happened while the puppets were in the box.