Asked by: Paul Mellor, St Albans
Our nervous system has evolved to become progressively less sensitive to a stimulus, the longer it persists. This enables us to concentrate on the newest sensations that are more likely to be an opportunity or a threat. We also have an olfactory memory that discards smells that we have experienced recently. This means that you don’t notice the smell of your house when you come home from work, but it smells strange when you come back from holiday.