One family of possibilities, to be evaluated in the next experiment, is that children learn more failed to attend to, remember, or understand the transformations. Note that this failure could not have been absolute, since if the transformations were simply deleted from their memory, the children would have responded based on the size of the starting set as in Experiment 1, leading to below-chance performance in Experiment 2. Nevertheless, it is possible that children knew that something had happened, but did not understand exactly what had happened and

how it impacted the set of puppets. Experiment 3 was undertaken to explore this possibility. Experiment 3 tested whether children could remember and process the transformations presented in Experiment 2 when the addition and subtraction events were performed on smaller sets, within the range of children’s mTOR tumor object-tracking abilities. Participants were 12 subset-knowers (7 female, mean age 33.94 month, 32:13–35:13). Displays were sets of 2 or 3 finger puppets, placed on a new tree that was constructed with only 3 branches. For the purpose of the branch addition/subtraction condition, additional trees were crafted to allow for the addition or removal of a branch (beginning with 2 or 4 branches

and ending with 3 branches). The children were first familiarized with the task using the same initial 3 trials as in Experiments 1 and 2. Following familiarization, children were given two trials in a puppet addition/subtraction condition, and two trials in a branch addition/subtraction condition, with order of presentation of condition and of trial outcome (2 puppets or 3 puppets) counterbalanced. The trials followed the procedure of Experiment 2, except with smaller sets of puppets and branches. For the puppet addition/subtraction condition, the outcome-3 trial started with 2 puppets on 3 branches, and the transformation event consisted in one puppet being taken from the sleeve of the experimenter and added to the box. The outcome-2 trial started with a group of 3 puppets on 3 branches, and the transformation Docetaxel cell line event showed one puppet being

removed from the box and hidden in a bag on the floor. In the branch addition/subtraction condition, the outcome-2 trial started with 2 puppets on 2 branches, and one extra branch was added to the tree while the puppets were in the box. The outcome-3 trial started with 3 puppets on 4 branches, and one branch was removed from the tree while the puppets were in the box. After each transformation event, the experimenter reached for the first puppet in the box and placed it on the tree. She then handed the box to the child. The searching time measurement started after the child had found the 2nd puppet and had placed it on the tree. Children solved this task easily (Fig. 4), showing a reliable effect of the Outcome size in the correct direction, F  (1, 10) = 307.7, p   < .001, ηp2=.97.