one's imagination; just one's mind playing tricks
Used when dismissing a feeling, suspicion, or perception as not real, often in the phrase 気のせいだ or 気のせいか.
I thought I heard someone call my name, but it was just my imagination.
Maybe it's just me, but it feels a little colder.
錯覚 is a more formal, clinical term for an illusion or misperception, whereas 気のせい is a casual everyday phrase used to dismiss a feeling as unreal.
Standard spelling; the kanji 気 is almost always used.
Rare kanji form using 所為; learners should stick to 気のせい.
From 気 (mind, feeling) + の (possessive particle) + せい (fault, cause). Literally 'the fault of one's mind', implying that the mind is responsible for a mistaken impression.