| Abstract: | Although the hierarchical levels of categories have been recognized as a major factor of variation in categorical reasoning, few studies have examined its effect on the understanding of inclusion. This issue was approached by varying the levels (subordinate, basic, and superordinate) of categories involved in inference tasks assessing 5‐, 7‐, and 9‐year‐old children's understanding of transitivity and asymmetry of inclusive relations in the dog hierarchy. Children were administered both a qualitative inference task and a quantitative class‐inclusion task, each presenting different hierarchical levels. Results showed that the ability to make qualitative inferences assessing transitivity varied with age. Although children of all ages demonstrated a high rate of success at these inference questions, 7‐ and 9‐year‐olds had better performance than 5‐year‐olds, suggesting that the capacity to understand the transitivity of inclusive relations still develops until at least 7 years. However, the hierarchical levels of categories had no effect on children's performance either in qualitative inferences requiring transitivity understanding or in class‐inclusion problems. In contrast, for qualitative inferences assessing asymmetry, children's performance varied with the hierarchical level of the categories involved. Inferring from a superordinate to a basic level category, inferring from a superordinate to a subordinate level category, and inferring from a basic to a subordinate level category appeared as three levels of increasing difficulty. Our analyses also revealed that 7‐year‐olds were better at grasping the asymmetry in the superordinate‐to‐basic relation than in any other relation between categories of different hierarchical levels, and that their 9‐year‐old peers mastered the asymmetric nature of inclusion in both superordinate‐to‐basic and superordinate‐to‐subordinate relations. This might indicate that the different levels of difficulty observed are developmentally grounded. Though exploratory, these findings help to clarify the steps through which the child comes to grasp the difficult concepts of inclusion and asymmetry and give some indications on the possible constraints that may affect their acquisition. |
