However, once this potential is present, other factors related with cumulative exposure to hierarchical structures may play a role in the representation of hierarchical self-similarity. For instance, in our study, prior experience with iterative rules was fundamental to the

understanding of recursion (but not vice versa). These results mimic the findings of language research (Roeper, 2011). Our results also suggest that age differences can be partially explained by differences in visual processing efficiency, since the effects of visual complexity are more pronounced in second graders, and this group is especially impaired in the detection of EGFR inhibitor ‘odd’ foils. Finally, also grammar comprehension abilities partially account for these grade differences, independently of general intelligence. This suggests that the ability to process hierarchical structures in the linguistic and visual domains partially recruit similar cognitive resources, although

these resources are not specific to recursion. If recursion were central to all syntactic processes in language, we would expect to find a specific correlation between visual and linguistic recursion, instead of a general correlation with hierarchical processing. Thus, our results seem to challenge Chomsky’s thesis (Chomsky, 2010). Our first important CAL-101 manufacturer result was a demonstration that 9- to 10-year-old children are well able to represent recursion in the visual domain. The fact that they are able to do so without instructions or response feedback, and with only a very short training session (4 trials), suggests that they are spontaneously able to generalize the knowledge of structural self-similarity across test items. Furthermore, we used different categories of foils, and found no performance differences between them. Bay 11-7085 This suggests that children who passed VRT did not rely on simple heuristic strategies, and were probably able to perceive all features necessary to represent hierarchical self-similarity. The fourth graders were also able to correctly continue non-recursive

iteration and there were no significant differences between recursive and non-recursive tasks, although more fourth graders tended to perform above chance in EIT than in VRT (77% vs. 69%). Perhaps more surprising was the finding that many second graders performed poorly in both recursive and non-recursive tasks. Since second graders are able to handle conjunctions (e.g. “John, Bill, Fred, and Susan arrived.”) and to some extent syntactic structures like “What is the color of Bill’s dog’s balloon?” (Roeper, 2007 and Roeper, 2011), we might expect them to perform adequately in a visual task that requires the representation of iterative processes embedded within hierarchical structures. However, only 35% of second graders scored above chance in EIT (and only 27% performed adequately in VRT).