Human Senses (2003) BBC

Part 3: Touch and Vision

Touch

Humans are very sensitive to touch and different parts of our body have different sensitivities. In fact, when it comes to our sense of touch, humans are similar to elephants.We have a few areas where we are extremely sensitive, just like the elephant's trunk, and the rest of our body is surprisingly insensitive, like the elephant's thick hide. The different density of touch sensors in the skin, in different parts of the body, explains why some parts of the body seem to have a much lower pain threshold. A microscopic splinter in a finger can be extremely painful, while a cut on your leg may not hurt as much!

Ultimately, pain involves much more than what's happening with the touch sensors in the skin. It has a lot to do with what's going on in the brain. At University College London, Professor Tony Dickenson has devised an experiment, using mild electric shocks, which reveals how much more painful something will feel if you believe it is going to hurt – and how painless it is, if you think you've taken a painkiller. Our minds can sometimes block out even the most excruciating pain. We visit Dr David Spiegel in Stanford University, who uses hypnosis to help combat severe pain that can't be tackled with drugs. Under hypnosis, patients have pins stuck in their hands and feels almost nothing.

In Hawaii, circus performer Jim Rose lies on a bed of blades and explains how to smash a breeze block on someone’s chest. Can all this really be painless?



Vision

Why is it that humans are so good at seeing some things, when at other times our brain can prevent us from seeing what's right in front of our eyes? Humans' real speciality is checking each other out.We're so good at it, we do it without even being aware of it. With the help of the latest eye-tracking technology and scientists from Sussex University, we show some unsuspecting volunteers what their eyes really get up to. We are also very skilled at gauging depth and distance.This episode explains how top baseball players manage to track a ball coming towards them at such high speed. It’s an extreme example of the basic hand/eye co-ordination that we all acquire as we grow up.

But to see how it feels to be back at square one, we spend a day with eccentric Professor Hubert Dolezal in Chicago, to experience the professor's 'upside-down goggles'. Almost a third of our entire brain is devoted to vision, but there's a limit to how much our eyes observe. In a simple experiment in a busy shopping centre, we set one person to ask shoppers for directions and then switch places with someone else while the shopper is distracted. Most people fail to notice the switch and carried on giving directions.

Dr Richard Wiseman of the University of Hertfordshire, explains that people's brains weren't paying attention to who was asking the questions because they were just concentrating on getting the directions right.

Source: http://www.bbcactive.com/BroadcastLearning/MediaSupportFiles/Human%20Senses%20synopsis.pdf

This sensory romp around the globe goes in search of the biological roots of our senses to uncover the reasons why particular sights, sounds, smells and tastes have such powerful effects on us. How do we manage to block out intense pain? How does our sense of balance keep working under the most extreme conditions? Live action combined with special effects creates incredible imagery to convey the 'feeling' of how our senses work. As an alarm bell goes off, we 'see' the noise, slowed down thousands of times. Ripples of sound roll towards us; we spin around and follow a sound wave as it travels into the dark outer ear canal.



The senses are our guide to the world, keeping us out of danger and directing us to pleasure. But how sensitive and accurate are they? And Just how intense a sensation can we bear? On a global assault course for the senses, our chief volunteer must endure many a sensory extreme - from the foulest smell to the hottest chilli pepper, while other, unsuspecting "volunteers" will unwittingly demonstrate just how easily our senses can be misled. We will also meet the sensory superstar of the animal kingdom, who can help to explain the biological roots of our own senses.





Are your eyes being tricked by your brain? Do you know what a supertaster is? Or how to avoid travel sickness? Put your senses to the test in our Senses Challenge.



Discover why food tastes bland if you can't smell.



The light hearted but revealing series explores, sense by sense, how they function and why we need them. Then delves so deep... you'll never hear, taste, touch, smell, stand, or see the same way again.

[edit] Smell and Taste



In the first programme of the series Nigel Marven goes in search of the most disgusting , the most attractive smells and sets out to discover the biological reasons why humans eat such a diverse range of foods, from rotten raw ducks eggs to a sweaty blue cheese. At a chilli eating contest, he pushes his taste buds to the limit.

[edit] Hearing and Balance



Sound can have a very powerful effect on how we feel about the world and Nigel Marven is on a quest to track down the sounds which have the most powerful emotional effects on us.Balance is our true sixth sense - it enables us to sense how our bodies are moving around in the world and keep us upright. There are only two kinds of animal that spend their whole lives performing the tricky balancing act of walking on two legs – humans and some flightless birds, like ostriches.

[edit] Touch and Vision



Humans are very sensitive to touch, but different parts of our body have different sensitivities. Nigel demonstrates that when it comes to our sense of touch, humans are similar to elephants.Nigel Marven sets out to discover why we are excellent at seeing some things, but sometimes miss what's right in front of our eyes.