When writing, it's all too easy to refer to what the character can see.
The green grass. The beer next to the barbecue. The blue sky and the yellow sun.
Humans, however, have more senses than that. In fact, when asked how many senses you have, most people would reply five: sight, sound, smell, taste, and touch.
The minute you incorporate these senses into your writing, the more involved the reader becomes.
The smell of freshly mown grass lingers in the air. Burgers sizzle on the barbecue, whilst damp beads of moisture on the beer bottle are tiny reminders of the sweet taste of cold nectar. Heat, glorious summer warmth, presses down on...
Wait a minute. Heat? Oh. OK, maybe there are six senses then. We can definitely sense heat.
But wait, there's more. Have you tried closing your eyes and then touching your right elbow with your left index finger? (You haven't lived until you've tried it.) It's an easy enough trick to do, yet that doesn't involve touch, or sight, or any of the other senses.
In fact, it involves a sense called proprioception, where nerves know where your body is in relation to how much stretch and length each of our muscles have. It's also the cause of phantom limbs, when new amputees say they can still feel their old limbs. The brain hasn't gotten used to the fact the limb isn't there, and so they sense where it should be.
So, we've seven senses. Cool.
Wait. Have you tried standing on one leg?
The reason you don't just fall over is because of your inner ear, where small semi-circular canals are full of fluid. They tell you which way you are moving, and you can then use your leg muscles to compensate for falling over. If you are drunk, the nervous system doesn't work so well, and those balancing messages might get delayed or confused, making the room seem to spin or leaving you needing to prop up a bar to stop you from falling over.
They can also be fooled. Ever played that school playground game of spinning round and round, looking upwards, then trying to walk forwards in a straight line? The liquid gets sloshed to one side, and takes a while to recover, so your sense of balance gets distorted. Another common problem is something aeroplane pilots need to be aware of. A sudden forward acceleration pushes you (and that liquid) back, giving you a sensation of tilting upwards. The opposite is true of slowing down.
OK. So we've actually got eight senses.
All of these senses can be used in our writing, and it's likely we have more than just those eight. Even more exciting for me is how they interact with each other.
Sight has a massive influence on our other senses. Let me give you a few quick examples.
When you watch a film, it's common that some sounds you hear (especially in fantasy or sci-fi films) aren't real. What's more impressive is that they can actually be of something completely different, but because your eyes see it at the same time, your brain makes it work. A classic example is the swooshing door sound on Star Trek, which was actually the sound of paper being taken out of an envelope and a sneaker squeaking on a basketball court, played at the same time. But, hear it as a door opens, and it's just the sound of the door opening.
Another example is how sight can affect taste. As humans, we don't want to eat something that could harm us, and so we have developed a sense (dang it, make that nine senses) of disgust when we see something that could be poisonous. Easy test? Imagine having a bowl of your favourite soup (yum) and then finding maggots writhing inside it (yuk!). The soup may well be unaffected, but you wouldn't want to eat it, and you'd be sure you could taste something horrid in there.
And don't get me started on blue food colouring.
