衝動 and 慎重: feeling an impulse and considering a decision
Read an impulse to paint beside thinking overnight to avoid an impulsive purchase. Compare careful checking and deliberation without inventing an action taken or the final buying decision.
The cause of an impulse and whether it was acted on
衝動 (しょうどう) names an impulse to do something. In 「美しい絵を見て、自分でも描きたい衝動に駆られた。」, seeing a beautiful painting produced an impulse to paint as well, but the sentence does not say that the speaker actually painted.
「衝動のままに高い物を買わないよう一晩考えた。」 says that the speaker thought overnight to avoid buying an expensive item on impulse. 「買わないよう」 gives the purpose and 「考えた」 the act of thinking, without stating the eventual purchase decision.
Careful checking and thinking before deciding with 慎重
慎重 (しんちょう) describes a careful attitude or manner of acting. In 「重要な書類なので慎重に内容を確認した。」, the document's importance explains why its contents were checked carefully; 「慎重に」 describes the manner of checking.
「彼は慎重な性格で、決める前によく考える。」 describes a cautious person who thinks carefully before deciding. This does not say that he lacks motivation or that he always postpones a decision.
An impulse can coexist with deliberation
The expensive-item example combines awareness of an impulse with thinking intended to avoid acting on it immediately. Feeling an impulse and following it are separate, so the presence of 衝動 does not establish that a hasty action was completed.
An impulse to paint should not automatically be labeled a bad feeling, and 慎重 should not be defined solely as delaying action. These examples distinguish the trigger for a desire, the manner of checking a document, and thought before a decision.
Does 「一晩考えた」 establish that the speaker ultimately decided not to buy the expensive item?
Show the answer and why
No final decision is given. The sentence states the purpose of avoiding an impulsive purchase and the act of thinking overnight. It does not say whether the speaker later bought the item or abandoned the purchase.