Module 3: Sensation and Perception

Absolute Threshold

The minimum stimulation needed to register a particular stimulus 50% of the time.

Signal Detection Theory

A model for predicting how and when a person will detect a weak stimulus, particularly based on context.

Difference Threshold

The smallest change in stimulation that can be detected 50% of the time.

Weber’s Law

We perceive differences on a logarithmic scale; it is the percent of change that matters, not the amount of change.

Transduction

The process of converting one form of energy into another, such as converting light waves into neural signals.

Hue

The color or shade that we perceive.

Purity

The richness or saturation of a color.

Red Light

Light with long frequency and most curvature.

Blue Light

Light with short frequency and least curvature.

Chromostereopsis

An optical illusion where pure colors at the same distance from the eye appear at different distances.

Amplitude in Light Waves

The amount of energy contained in a given lightwave.

Edge Detection

The process of identifying and locating sharp discontinuities in an image.

Feature Detectors

Neurons that respond to specific features of visual stimuli such as edges, angles, and movement.

Parallel Processing

The ability to process and analyze many aspects of a situation simultaneously.

Depth Perception

The visual ability to perceive the world in three dimensions and to judge the distance of objects.

Occlusion

A depth cue where an object that blocks the view of another object must be in front of it.

Relative Size

A depth cue indicating that smaller objects are perceived as being farther away.

Texture Gradient

A depth cue where texture appears smaller and less distinct as it gets farther away.

Relative Height

A cue indicating that objects appearing higher in the visual field are farther away.

Familiar Size

Knowledge of the normal size of certain objects can provide cues to perceive depth.

Linear Perspective

A depth cue where parallel lines seem to converge as they move into the distance.

Aerial Perspective

A depth cue where objects farther away appear hazier and bluer.

Relative Brightness

A depth cue indicating that brighter images are perceived as closer and shaded images as farther away.

Proximity (Gestalt Principle)

The tendency to group figures that are close to each other perceptually.

Good Continuation

A Gestalt principle where there is a preference for organizing forms in a way that contours continue smoothly.

Closure (Gestalt Principle)

The tendency to fill in information to complete perceptions.

Philosophy of Perception

Perception is a hypothesis, not knowledge.