Sensation is the process by which sensory systems (eyes, ears, and other sensory organs) and nervous system receive stimuli from our environment.

Perception is the process of organizing and interpreting incoming sensory information.

Sensation

Bottom- up processing◦ Information processing

that analyzes on the raw stimuli entering through the many sensory systems.

Top- down processing◦ Information processing

that draws on expectations and experiences to interpret incoming sensory information.

Two types of processing

Top- Down Processing

Absolute Threshold◦ The minimum amount of a stimulation needed to detect a

particular stimulus.◦ Amount of a stimulus that a person can detect 50% of the time

Difference Threshold◦ The minimum amount of difference needed to detect that two

stimuli are not the same.◦ Also called just noticeable difference

Basic Principles of Sensation

A theory that predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise).

Three kinds of variables

◦Stimulus variables◦Environmental variables◦Organismic variables

Signal Detection Theory

Diminished sensitivity to constant and unchanging stimulation.

If a stimulus is constant and unchanging, eventually a person may fail to respond to it

Sensory Adaptation

Focusing conscious awareness on a particular stimulus to the exclusion of others.

The ability to focus on one stimulus at a time Allows a person to function in a world filled with many

stimuli

Selective Attention

Selective Attention