In a recent installment of New Scientist's Last Word series, readers tackled a deceptively simple question: do olfactory illusions exist, similar to optical and audio ones? The responses broadly say yes, but with an important caveat: smell's illusions often depend on the brain's interpretation rather than the nose alone.
Several readers described how the same odor can be experienced differently depending on its source or the situation. A smell that seems pleasant in one context may become unpleasant when associated with something else, suggesting that expectation and prior experience can override raw sensory input. Others noted that visual cues, such as seeing a familiar object, can alter what we think we are smelling.
While the readers differ on the exact mechanisms, they converge on the idea that olfactory perception is constructive—our brains actively build a smell experience from incomplete information. This makes olfactory illusions a useful window into how the sense of smell works, even if they are less famous than their visual and auditory counterparts.