This dissertation explores the origin and development of causal reasoning. Paper 1 and Paper 2 explored 8.5-month-old infants' causal representations of state change events. Paper 1 investigated the influence of the type of agent on infants' causal representations of state change events (breaking box, color change). Infants represented a human hand and a novel, self-propelled entity with eyes, but not an object, as the cause of a state change event. A further experiment provided evidence that infants formed causal representations of the state change events. Paper 2 explored the relation between infants' representations of causal agents and intentional agents. Infants attributed the cause of a state change event only to entities they were likely to have represented as intentional agents. These findings suggest that (1) representations of intentional agents act as inputs to infants' early causal representations, (2) infants' causal representations extend beyond motion events, to state change events, and (3) representations of causal agency are closely related to representations of intentional agency early in development.

Paper 3 explored 3.5- to 4-year-old children's conceptual and linguistic representations of cause. Children were presented with causal events that varied in the type of agent (human acting intentionally, human acting unintentionally, object) and the type of effect (motion, state change). Across two experiments children displayed an intention-to-CAUSE bias – children produced more causal language (causal verbs, causal syntactic frames) and preferred causal descriptions more for intentionally caused events than for unintentionally caused and object-caused events, independent of the type of effect. A further experiment, using a counterfactual reasoning task, revealed that children were equally likely to conceptually represent all of the events as causal. Taken together, these findings suggest that the type of agent, but not the type of effect, influences how children map conceptual representations of causal events into language.

The findings from this dissertation have implications for our understanding of the domain-specificity of early causal representations, the inputs to early causal representations, and the continuity of early causal representations across development.