Perception Introduction
When we smell a fragrant flower, are we experiencing a sensation or a perception? In everyday language, the terms "sensation" and "perception' are often used interchangeably. However, as you will soon see, they are very distinct, yet complementary processes.
Sensations can be defined as the passive process of bringing information from the outside world into the body and to the brain. The process is passive in the sense that we do not have to be consciously engaging in a "sensing" process.
Perception can be defined as the active process of selecting, organizing, and interpreting the information brought to the brain by the senses.
• For example, the eye turns two dimensional information into three dimensional information.
• Vision is perhaps our most important sensory process. About 80% of the information we receive about the external world reaches us through vision.
• Visual perception appears to be such a simple and effortless process that we often take it for granted. However, it is extremely complicated.
Definitions of Perception
• Perception is the “interpreting of sensory information”. (Heyes & Orrell)
• Perception is “a dynamic searching for the best interpretation of available data”. (Gregory)
• Perception is “the process of assembling sensations into a useable mental representation of the world”. (Coon)
What these definitions have in common:
• Sense data is the raw material from which our consciousness (ie. awareness) of the world is constructed.
• What we perceive is constructed from the information in our environment.
What Does Perception Do?
• Perception provides useful, organised, and stable interpretation of sensation.
• Allows a person to recognise things – ie. a meaningful interpretation of the world.
• Perceptual systems have evolved to be relevant to the world to the organism rather than reproduce reality. For example, perceptual constancies (eg. size constancy) ensure the stability of our visual world.
Perception Audio Broadcasts 
Listen to a MIT undergraduate lecture on Perception.
Listen to a MIT undergraduate lecture on Sensation.
Listen at a BBC broadcast about Perception with Melvyn Bragg
All broadcasts require Real Audio Player.
Perception PDF Downloads 
What do visual illusions teach us?
