Sensation and Perception Chapter 3
Sensation • The process that occurs when special receptors in the sense organs are activated, allowing stimuli • What are the 5 senses?
Perception • The method by which the sensations experienced at any given moment are interrupted and organized in some meaningful fashion • When your brain collects data, organizes it, and interprets it to give those sensations meaning • Examples?
Just Noticeable Difference • AKA Difference Threshold • Ernst Weber • The smallest different between two stimuli that is detectable 50 percent of the time by 50 percent of the people tested • Read example on the top of page 79 • Class demonstration
ABSOLUTE THRESHOLD • THE LOWEST LEVEL OF STIMULATION THAT A PERSON CAN CONSCIOUSLY DETECT 50 PERCENT OF THE TIME THE STIMULATION IS PRESENT • The brain is only interested in changes in information
HABITUATION • Although you may hear something, you may not notice it • How your brain deals with unchanging information from the environment • Very similar to sensory adaptation – tendency of sensory receptor cells to become less responsive to a stimulus that is unchanging • Without sensory adaptation the trash would never stop smelling, the noises would never stop being annoying, and the clothes would never be comfortable. Video Class demonstration
SENSORY RECEPTORS • Receptor cells are stimulated by different kinds of energy • Page 80 • Some things we can’t see, hear, feel • If you had to give up one of your senses, which one would it be and why?
Perception • The method by which the brain takes all the raw data sensations people experience at any given moment and allows them to be interpreted in some meaningful fashion in the brain • Help us interact with our environment
Perceptual Constancies • There are 3 • Size constancy – the tendency to interpret an object as always being the same size, regardless of its distance from the viewer
Perceptual Constancies • Shape constancy – interpret the shape of an object as a constant, even when it changes on the retina • Why a person still perceives a coin as a circle even if it is held at an angle that makes it appear to be an oval on the retina
Perceptual Constancies • Brightness constancy – the tendency to perceive the apparent brightness of an object as the same even when the light conditions change • Dark day – bright day
Gestalt Psychology • Believes that people naturally seek out patterns (“wholes”) in the sensory information available to them • Figure ground – tendency to perceive objects or figures as existing on a background • Reversible figure – the figure and the ground seem to switch back and forth
Proximity • Tendency to perceive objects that are close to one another as part of the same grouping • Similarity – tendency to perceive things that look similar as being part of the same group • Closure – the tendency to complete figures that are incomplete • Continuity – tendency to perceive things as simply as possible with a continuous pattern rather than with a complex, broken up pattern • Contiguity – the tendency to perceive two things that happen close together in time as being related Figure on page 96
Depth Perception • Ability to see the world in three dimensions • The Visual Cliff on page 97 – read it and answer questions • Monocular vs. binocular cues
Pictorial Depth Cues • Break up the 7 • Teach class
Binocular Cues • Convergence – making a triangle with you eyes to converge on one object • Binocular disparity – two different eyes two inches apart see different things
Illusion • Perception that does not correspond with reality • Video • Figure 8.5 on page 99 – which line is longer? • Auto kinetic effect – light moving in a dark room • Stroboscopic motion – flip books still pictures will seem to move • video
Perceptual set or expectancy • People’s tendency to perceive things a certain way because of previous experiences or expectations influence them • Class demonstration page 100 • Figure 8.6 on page 100
Perceptual set • Top-down processing – the use of preexisting knowledge to organize individual features into a unified whole. • Ex: completing a puzzle – putting together a table • Bottom-up processing – analysis of smaller features and building up to a complete perception • Ex: no puzzle top – no directions of completed table • Video • Subliminal advertising page 101 • Practice quiz page 102