Sensation and Perception

Sensation: your window to the world Perception: interpreting what comes

in your window.

Just the basics…• Bottom-up processing• Top-down processing• Thresholds– JND

• Signal detection• Subliminal

Subliminal stimulation

ABSOLUTE THRESHOLD

Signal detection theorySensory experience

Your clothes are touching your skin.

Sensory Adaptation• Decreased

responsiveness to stimuli due to constant stimulation.

Vision• Our most

dominating sense.

Transduction• Order is Rods/Cones

to Bipolar to Ganglion to Optic Nerve.

• Sends info to thalamus- area called lateral geniculate nucleus (LGN).

• Then sent to cerebral cortexes.

• Where the optic nerves cross is called the optic chiasm.

In the Brain• Goes to the

Visual Cortex located in the Occipital Lobe of the Cerebral Cortex.

• Feature Detectors.

• Parallel Processing

We have specific cells that see the lines, motion, curves and other features of this turkey. These cells are called feature detectors.

Rods vs. Cones

• http://faculty.washington.edu/chudler/retina.html

• http://science.howstuffworks.com/environmental/life/human-biology/eye2.htm

Color Vision

Two Major Theories

Trichromatic TheoryThree types of cones:• Red• Blue• Green• These three types of

cones can make millions of combinations of colors.

• Does not explain afterimages or color blindness well.

Opponent-Process theory

The sensory receptors come in pairs.

• Red/Green• Yellow/Blue• Black/White• If one color is

stimulated, the other is inhibited.

Afterimages

Hearing

Our auditory sense

The Ear

• How we hear• Baby with cochlear implants• Cochlear implants

Touch• Mechanoreceptors

located in our skin.• Pressure, warmth, cold,

pain

Pain• Sensory vs. affective• Controlling pain– Endorphins– Gate control theory– Placebo control– Distraction

• Phantom limb• Social influences

Taste• Tongue– Papillae

• Taste buds– Taste cells

» Receptor sites• Sweet, salty,

sour, and bitter.• Flavor = taste +

olfaction

Vestibular Sense• Tells us where

our body is oriented in space.

• Our sense of balance.

• Located in our semicircular canals in our ears.

Kinesthetic Sense• Tells us where

our body parts are.

• Receptors located in our muscles and joints.

Olfactory• Chemistry– Individual signature

• Learned associations

Perception

GESTALT• a structure, configuration, or pattern

of physical, biological, or psychological phenomena so integrated as to constitute a functional unit with properties not derivable by summation of its parts

Law of Good Continuation

Law of Common Fate

Figure Ground Relationship

Our first perceptual decision is what is the image is the figure and what is the background.

Constancy• Objects change in

our eyes constantly as we or they move….but we are able to maintain content perception

• Shape Constancy• Size Constancy• Brightness

Constancy

Perceived Motion• Stroboscopic

effect (flip book effect)

• Phi phenomenon

Depth Perception• Monocular cues– Linear Perspective– Interposition– Relative size– Texture gradient– Shadowing

• Binocular cues– Retinal disparity– Convergence

Depth Perception

• Visual cliff experiment• 3D movies – retinal disparity

Variations in PerceptionInborn organizations + Learned

Variations• Adaptation• Perception set

(priming/predisposition)• Context• Emotion• Motivation

Human Factor Psychologists• AFFORDANCE– “It’s not your fault you turned on the

wrong burner…”