The knight is hanging. You see it half a second after your opponent does, and something in your chest drops before you've even worked out how bad it actually is. That reaction shows up whether the loss costs you the game or barely matters to the position. It's worth understanding, because what happens in the next few moves depends far more on that reaction than on the missing piece.
Why the reaction is bigger than the loss
Losing a piece registers in the body before it registers on the scoresheet. It reads as a threat, the same category of alarm as dropping something valuable or making a visible mistake in front of someone. That response is useful in most of life. In chess it's often out of proportion: a lost knight in a position with real compensation is not the same as a lost knight in a position with none, but the first jolt of panic doesn't know the difference. It only knows something was taken.
The loss usually isn't the actual problem. The problem is that the panic arrives first and starts making decisions before you've assessed anything at all.
Separating the feeling from the position
A habit that helps: when you notice that drop in your chest, treat it as information about you, not about the position. Take one breath, then ask the actual chess question. What is the material and positional balance right now, not what it felt like a second ago. Sometimes the piece really is just lost, and the position really is worse. Often it isn't as bad as the first jolt suggested, and the only real danger left is playing the next three moves in a hurry to make up for it.
Kids are especially prone to this, and it's worth naming out loud for them early. Losing a piece is not the same as losing the game, and the board has no idea how upset you are about it.
