<PERSON> (2005)  Goal: retrieve food from within box  Irrelevant action: insert tool into top hole (inner barrier)  Relevant action: insert tool into front hole  Both Irrelevant and Relevant actions modeled  Some children see demonstration with clear box (causal structure observable), some with opaque box (causal structure unobservable) <PERSON> (2005)  Goal: retrieve food from within box  Irrelevant action: insert tool into top hole (inner barrier)  Relevant action: insert tool into front hole  Both Irrelevant and Relevant actions modeled  Some children see demonstration with clear box (causal structure observable), some with opaque box (causal structure unobservable)