sensory illusion

An illusion is a misrepresentation of a real sensory stimulus, leading to a perception that contradicts objective reality. These false impressions can arise from external factors, such as the bending of light that makes a pencil in water appear bent, or from the way our senses process information.1

Illusions are distinct from hallucinations, which lack an external source of stimulation. While some illusions are caused by physical phenomena distorting stimuli (stimulus-distortion illusions), others stem from how our brains interpret sensory cues (perceiver-distortion illusions). These can include visual illusions like the Müller-Lyer illusion, where lines appear different lengths due to arrow-like markings, or auditory illusions such as the Doppler effect. Cultural environments can also influence susceptibility to certain illusions.12