Скачать или смотреть The sound of silence - Colin Blakemore's 1982 Christmas Lectures 2/6

In the second lecture of the series, Colin Blakemore explores the science behind the senses, with some animal guests to demonstrate.

Watch all the lectures in this series here:    • Colin Blakemore's 1982 CHRISTMAS LECTURES  
Watch our newest Christmas lectures here:    • Royal Institution Christmas Lectures  

This lecture was recorded at the Ri on 20 December 1982.

Find out more about the CHRISTMAS LECTURES here: https://www.rigb.org/christmas-lectures

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Lecture 2: The sound of silence

Just like photometers, microphones, compasses, smoke detectors, and other instruments made by man, sense organs have the task of detecting physical energy or the chemical nature of substances. Like instruments of detection and measurement the quality of their performance depends on two factors - their sensitivity to very weak signals and their ability to provide accurate information over a very wide range of intensity of stimulation. And, like man-made instruments, sense organs have problems of internal noise: when working at very high sensitivity they run the risk of confusing weak but genuine signals and random, false activity in the sense organ itself. The photosensitive rods in the retina of the human eye, which are responsible for vision in very dim light, are so sensitive that they can generate a signal when they catch a single quantum of light, the smallest unit of energy in which light can be delivered. And if the human ear were just a little more sensitive we might 'hear' the random Brownian motion of molecules inside the ear itself. Throughout the animal kingdom there are examples like this of extraordinary sensitivity of sense organs so good that sometimes the physical properties of the signals they detect limit their performance rather than the biological properties of the sense organs themselves. However the senses must be able not only to detect very weak events but also to discriminate between many different kinds of signals and to send information to the brain about a fantastic range of energy levels. The sun is about ten thousand million million times brighter than the dimmest light that we can see so the eye must be able to operate over that entire range. The prodigious ability of sense organs to analyse and discriminate between signals over wide operating ranges is especially surprising in view of the fact that they send their messages along rather low-quality cables - the nerve fibres that connect them to the brain.

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About the 1982 CHRISTMAS LECTURES: Common Sense

Our sense organs are windows on the world. But just like windows, as well as giving us a view of the physical world, the senses also restrict our outlook on the things around us. Philosophers have worried for centuries about the reliability of the human senses and about the relationship between the real world and the world as we see, hear and feel it. Is the world only a creation of our minds? I am no philosopher, so I am happy to accept that there is a real world out there and that our sense organs simply describe it to our brains. But this means that the world we know through our perceptions is created by processes in our brains and the validity of this imagined world depends crucially on the way that our sense organs and our brains work together to perform the magic of perception. My aim in these lectures is to describe the way that the sense organs act as biological instruments of detection, measurement and analysis. I shall try not to be a 'human chauvinist' but will show that our senses, perfect though they are for our needs, are only a small part of the repertoire of biological instruments of detection and measurement that evolution has invented. It is hard to accept that our perception of things around us is incomplete, but the fact is that we are blind and deaf to much that is happening in the world. We sense what we need to sense. Every animal lives in its own perceptual world, a world of its own creation. Let us be proud of the incredible performance of our own sense organs and brains but let us not forget that other creatures have marvellous sense organs that we do not. They live in other worlds, in perceptual worlds created by their own particular sense organs, worlds that we can never experience directly but can only dream about. Join me in these lectures on a journey to the edges of your own perceptual world and into the sensory worlds of other animals.
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About Colin Blakemore:

Sir Colin Blakemore (1 June 1944 – 27 June 2022) was a British neurobiologist, specialising in vision and the development of the brain. His own research work was mainly concerned with the mechanisms in the brain for the interpretation of signals from the eyes, and especially in the early development of vision during the first few days and weeks of an animal's life. He was well known for his work in communicating science to the public and published many popular books.