Passage Summary: After kids learned what 'stairs' were, they saw a ladder and called it 'stairs' too.

Reasoning: Children who learned the word 'stairs' while using a staircase immediately applied that same word to a ladder, which shares similar physical and functional traits.

Analysis: This stimulus illustrates a principle of cognitive generalization. The children are taking a label learned in one specific context and applying it to a new object that looks or functions similarly. Since this is a 'Principle' question, you want an answer that generalizes this specific behavior into a broader rule. Look for a statement suggesting that initial language acquisition often involves categorizing new objects based on their resemblance to the original example. It's a classic case of a child's 'over-extension' of a category based on shared features like 'things you climb with steps.'