370: Introduction

1. Perception is deceptively hard
1. Perception’s job is to take in input through receptors and determine what is out there in the world
1. We perceive things effortlessly but if one were to attempt to reproduce what we do it is extremely complex
2. 50-60% of the brain is devoted to seeing
3. Eyes just measure light
2. Perceptual problems are usually ill-posed
1. ill-posed
1. not enough info to determine answer
2. Example
1. World is 3D
2. We perceive it’s 3D structure correctly 
3. But the input is 2D
3. Perception is (unconscious) inference
1. Information in sensory input does not uniquely specify structure of the world
2. Brain has to make it’s best guess
4. “Illusions” illustrate perceptual mechanisms at work and can help us study them
1. Illusions tell us where the system breaks down which tells us where our brain takes short cuts
5. Quantitative Methods in Perception
1. Our eye can detect a minimum of one photon (although it takes 7 to get that one photon to the eye)
6. A Detection Experiment
1. determine whether or not an ‘X’ is present
7. Different Sources of Noise
1. Internal noise
2. External noise