"However, in the situation I describe, they are looking at the road ahead and not noticing me or where I might be looking. " There is something called peripher

"However, in the situation I describe, they are looking at the road ahead and not noticing me or where I might be looking. " There is something called peripheral vision https://en.m.wikipedia.org/wiki/Peripheral_vision https://en.m.wikipedia.org/wiki/Peripheral_vision If there is a movement in the corner of the eyes, like someone turning their head towards you, you can spot it subconsciously, or if you trained it a bit, consciously.