Straying outside of baseline

The reason polygraph test operators start with a serious of basic questions – “Are you a man?” or “Do you have black hair?” – is to establish a baseline of how somebody functions under normal conditions when telling the truth. Since each person acts differently and has their own unique quirks, it’s important to establish a baseline of the person’s behavior to know when they’re straying from it and potentially lying. (As for polygraph tests, just being asked questions knowing someone is looking to find you lying may create enough anxiety to make it look like you’re lying even when you’re not.)