Presenting test subjects with a vial of colored liquid can cause them to report smelling something even when no odorants are present.

Question

Quizplus · Accepted Answer

This phenomenon is known as "suggestion-induced smell responses" or "olfactory suggestion". It happens because our sense of smell is interconnected with our other senses like vision and expectation, and can be influenced by contextual cues. Seeing a vial of colored liquid may suggest a certain scent, which the brain then creates, even if no odorants are actually present.

Presenting Test Subjects with a Vial of Colored Liquid Can