What is natural stimulus or unnatural stimulus?

A natural stimulus is an environmental cue or event that occurs in nature and elicits a response from an organism, such as the sound of a predator or the presence of food. In contrast, an unnatural stimulus is typically a man-made or artificial cue that may not exist in the organism's natural environment, such as a loud noise from machinery or flashing lights. Both types of stimuli can trigger specific behavioral or physiological responses in organisms.