Sensation and Perception

Sensation: your window to the world PerceptionPerception: interpreting what comes in

your window. http://www.theinvisiblegorilla.com/videos.html

Sensory Adaptation

• Decreased responsiveness to stimuli due to constant stimulation.

Do you feel your underwear all day?

Vision• Our most

dominating sense.• Visual Capture

Phase One: Gathering Light

• The height of a wave gives us it’s intensity (brightness). • The length of the wave gives us it’s hue (color).• ROY G BIV• The longer the wave the more red.• The shorter the wavelength the more violet.

Phase Two: Getting the light in the eye

Phase Four: In the Brain

• 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.

Nearsighted Vision

Farsighted Vision

Color Vision

Two Major Theories

Trichromatic Theory

Three 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

We hear sound WAVES

• The height of the wave gives us the amplitude of the sound.

• The frequency of the wave gives us the pitch if the sound.

Cocktail-party phenomenon

• The cocktail party effect describes the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations.

• Form of selective attention.

Transduction in the ear• Sound waves hit the

eardrum then anvil then hammer then stirrup then oval window.

• Then the cochlea vibrates.• The cochlea is lined with

mucus called basilar membrane. And its hair cells.

• When hair cells vibrate they turn vibrations into neural impulses to thalamus up auditory nerve.

It is all about the vibrations!!!

DeafnessConduction Deafness

• Something goes wrong with the sound and the vibration on the way to the cochlea.

• You can replace the bones or get a hearing aid to help.

Nerve (sensorineural) Deafness

• The hair cells in the cochlea get damaged.

• Loud noises can cause this type of deafness.

• NO WAY to replace the hairs.

• Cochlea implant is possible.

Touch

• Receptors located in our skin.

• Gate Control Theory of Pain

Taste

• We have bumps on our tongue called papillae.

• Taste buds are located on the papillae (they are actually all over the mouth).

• Sweet, salty, sour and bitter.

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.

Without the kinesthetic sense you could touch the button to make copies of your buttocks.

Perception

The process of organizing and interpreting information, enabling us to

recognize meaningful objects and events.

Subliminal Messages

• Stimuli below our absolute threshold.

• Backmasking• 25th frame• Do Subliminal

Messages work?• Probably a placebo

effect

Do you hear "Now he uses marijuana.“?

Do you hear “Ah, see me. I'm not too young”?

Do you hear Pass the gun now. It kills the love, the love is cold”?

Do you hear"Play backwards. Hear words sung.“?

(Just Notable Difference) Difference Threshold

The smallest amount of change needed to detect in a stimulus before we detect a change.

Weber’s Law

• The change needed is proportional to the original intensity of the stimulus.

• The more intense the stimulus the more change is needed to notice the difference.

• 8% for vision.

Perceptual Ideas

Signal Detection theory

• Absolute thresholds are not really absolute.

• Things like motivation or physical state can effect what we sense.

One of my friends could sleep through a war, but if one of her sons even whimpers, she is up!!!

Figure Ground Relationship

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

Gestalt Psychology• Gestalt psychologists focused on

how we GROUP objects together.• We innately look at things in

groups and not as isolated elements.

• Proximity (group objects that are close together as being part of same group)

• Similarity (objects similar in appearance are perceived as being part of same group)

• Continuity (objects that form a continuous form are perceived as same group)

• Closure (like top-down processing…we fill gaps in if we can recognize it)

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 • Autokinetic Effect

(if people stare at a white spotlight in a dark room, it appears to move.)

Depth Cues• Eleanor Gibson and her

Visual Cliff Experiment.• If you are old enough to

crawl, you are old enough to see depth perception.

• We see depth by using two cues that researchers have put in two categories:

• Monocular Cues• Binocular Cues

Monocular Cues

• You really only need one eye to use these (used in art classes to show depth).

• Linear Perspective• Interposition• Relative size• Texture gradient• Shadowing

Binocular Cues

• We need both of our eyes to use these cues.

• Retinal Disparity (as an object comes closer to us, the differences in images between our eyes becomes greater.

• Convergence (as an object comes closer our eyes have to come together to keep focused on the object).