Fill your paper with the breathing of your heart. William Wordsworth
It’s not just poets who use metaphors. We all do. Some have become so deeply entrenched we hardly recognise them, for example ‘deadline’, which derives from the literal line around a prison beyond which, should a prisoner go, they would be shot. The language experts have branded these, inaccurately, ‘dead metaphors’ . They may have lost their freshness but they certainly live on in everyday language.
In recent years, neuroscientists have also been taking an interest in the metaphor. They have investigated how our attempts to turn abstractions into something more concrete are processed in the brain. Their findings reinforce an important lesson for writers: choose words that can arouse all five senses.
In 2006, the journal NeuroImage published a study by researchers in Spain who asked participants to read words with strong associations to smell. The participants were scanned by a functional magnetic resonance imaging (fMRI) machine. When they saw the words ‘cinnamon’ ‘perfume’ and ‘coffee’ not only did those parts of the brain that control language light up, so did the olfactory cortex. At Emory University in the United States, by changing the sentence ‘the singer had a pleasing voice’ to one with a tactile metaphor ‘the singer had a velvet voice’, the researchers activated the sensory cortical region, which had not responded to the word ‘pleasing’. Similarly, ‘he had leathery hands’ triggered a more widespread reaction than did ‘he had rough hands’.
Perhaps these scientific discoveries explain why wordsmiths don’t usually like the mixed metaphor, where two inconsistent images are used in the same description:
Some people sail through life on a bed of roses like a hot knife slicing through butter.
Asking different parts of the brain to process simultaneously the images of yachts, roses (and maybe their thorns), blades and butter is a recipe for confusion rather than clarity.
By the way, I should explain the difference between metaphors and similes (both used in the example above) or, rather, let Ann Edwards do so:
While both similes and metaphors are used to make comparisons, the difference between similes and metaphors comes down to a word. Similes use the words like or as to compare things—’Life is like a box of chocolates’. In contrast, metaphors directly state a comparison—’Love is a battlefield’.