Perception, Sensation

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“Perception is more than just a sensation”

Introduction
Sensation is the passive process of bringing information from the outside world into the body and brain. Perception is the active process of selecting, organising and interpreting the information brought to the brain by the senses. Sensation and perception are two distinct processes, which collaborate to help us make sense of our environment. Perception requires physiological mechanisms and psychological components, these combine to help us understand. Perception is the process of how we acquire and understand information, sophisticated perceptual mechanisms go to work in order for us to gain knowledge. Our perception of the world is “direct, immediate and effortless” (Mather, 2006). Understanding how perception works is extremely complex and people differ in how they perceive, humans are quick to perceive as Biederman (1990) showed people can recognise and interpret complex novel scenes in as little as 1/10th of a second. The differences between sensation and perception are based around the fact that sensation is a physiological process stemming from one of the five senses, sight, hearing, smell, taste and touch. These senses enable us to detect stimuli in the environment. Perception on the other hand involves an understanding of this sensory information, drawing from the stimuli detected from the senses, our minds must process that information and create a mental representation of the senses. How our mind perceives this depends upon our background knowledge. For example if we smell sour milk, our nose picks up the smell which is the sensation, then perception plays its part by telling us that the milk has passed its used by date. Sensory organs absorb energy from physical stimuli in the environment which pass to sensory receptors these detect stimulus energies and convert them into mental impulses which are sent to the brain. Now perception begins, upon receiving the impulses the brain organises the input and translates it into something meaningful. However perceptions are not always accurate. The picture below is called the Muller- Lynn illusion. People are asked which line is bigger and people immediately answer with the bottom line, when in fact they are even. This shows that perceptions can be deceived quite easily. What we ‘see’ is not the same as what is ‘there’. Perception and reality differ. Numerous illusions show that the human mind can misinterpret information and inaccurately perceive senses, these include the Poggendorf illusion and the Penrose staircase. Muller-Lynn Illusion.

Perception
People perceive through sight, which is one of the senses. The physical stimulus for visual perception is light. (Wavelength > colour and Intensity > brightness.) Light interacts with objects. (e.g refraction, bending of light.) This forms the basis of how we perceive visually.

Colour is the most important component of our visual experience, some of the earliest theories of perception were developed from how we perceive colours. In order to explain colour perception one has to be familiar with, 1.Hue – variations in wavelength, difference between colours. 2.Brightness- the intensity of energy, black v white

3.Saturation – purity of colour, difference between pink and red (how much black/white added to the colour) The human can identify approximately 200 hues, 500 intensity steps and 20 saturations, combining to nearly two million colours. Does colour exist? People just assume that because we see colours, they actually exist in the world. Meaning, that when they see the colour red, that red is a real, physical, tangible, "thing". But is it, or is colour just a matter of our perception? If we had different types of nervous systems, we would see things differently (literally) and so wouldn't we think those other things we saw were the real "things"?

The Trichromatic theory
Thomas Young, a 19th century English scientist suggested that it takes just...
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