How do you make decisions about the world around you?

Stimuli What is the information OUTSIDE your body called? Stimuli include: light sound heat pressure chemical

What is it called when the stimuli are detected and transferred? Sensation (A physical reaction within the body in response to an external stimuli)

Perception Sensation + Past Experience = (The organization of sensation into meaningful information)

Sensation is to perception as________ is to ___________ A. Interpretation; organization B. Transmission; interpretation C. Integration; interpretation D. Adaptation; interpretation

Sensation is to perception as________ is to ___________ A. Interpretation; organization B. Transmission; interpretation C. Integration; interpretation D. Adaptation; interpretation

Do we detect every stimulus in our environment? No, it has to be strong enough for us to detect. We have a sensory threshold. Two types of sensory thresholds. - Absolute threshold - Difference threshold

Absolute threshold The smallest possible strength of a stimulus that can be detected half the time.

Difference Threshold (Just Noticeable Difference) the smallest possible change in a stimulus that can be detected half the time. True OR false? ……. Our sensory experiences depend more on changes than the absolute size of the stimulus.

Difference Threshold (Just Noticeable Difference) True Sensory experiences depend more on changes than the absolute size of the stimulus.

Difference Threshold (Just Noticeable Difference) Example – What do you notice more? 3# brick into an empty backpack? OR 3# brick into a 100# backpack ?

Weber’s law The larger or stronger a stimulus, the larger the amount of change required for an observer to notice a difference. Doubling sweetness takes 3x the sugar 2x the light < doubly bright

Sensory Adaptation -Our sensory receptor cells become less responsive to a constant stimulus. -This allows us to quickly notice new or changing stimuli.

Sensory Adaptation Give me an example: Movie theater lighting pressure of your clothes hot / cold (esp. water) Odors in a lab Street noise (background)

Sensory Adaptation (p. 212)

Signal Detection Theory Studies the relationship between: Motivation, Sensitivity &, Decision Making Different thresholds depending on the circumstances (importance of the detection matters) Radar operator “looking” for a blip Expecting to see someone at a party

THE SENSES Vision Hearing Smell Taste Touch Vestibular Kinesthetic

VISION Light waves….rods & cones in eyes Controlled by Occipital lobe Vision involves changing light energy into energy of the nervous system.

Rods and Cones RODS Not sensitive to color. Require little light to function…… useful in night vision.

Rods and cones CONES Sensitive to color Require more light than rods…… useful for daytime vision. Study tip: cones = color…..both start w/ c.

Binocular fusion - The combining of the two images that the eyes receive. Retinal disparity - The difference between the two images on the retina.

Hearing

Hearing Sound waves move hairs in Ears Controlled by: upper temporal area of cerebral cortex Ear bones convert vibrations into signal

Taste Chemical molecules Soluble substances on taste buds of the Tongue Controlled by: Cerebral cortex (temporal lobe) What is the Stimulus? Chemical molecules

Mr. Tongue

Smell Volatile substances contact hair cells in nose Controlled by: olfactory bulb (front temporal) Olfactory nerve one of the longest in the body….1 synapse on the way to the brain!

Smell

Touch Pressure, warmth, cold and pain receptors in the skin Controlled by: parietal lobe “headband” Sensitivity to pressure varies from place to place in the skin. (Mr. Homunculus & p 235)

Vestibular Mechanical / gravitational forces operate on inner ear Controlled by: cerebellum & parietal lobe Regulates the body’s sense of balance by sending messages from semicircular canal fluid to brain.

Kinesthetic Body movements w/in muscles/joints/tendons Controlled by: cerebellum & cerebral cortex (esp. parietal) Senses movement and position of body parts

Kinesthetic: How does it work? Sensory neurons located in the joints and muscles communicate information to the brain about changes in body position. Maintain posture & balance

Gestalt The perception of stimuli as “wholes”rather than bits and pieces.

x x x x oo X xx

x x x x oo X xx

Three Gestalt principles Closure Proximity Similarity

Closure Tendency to group according to enclosed or completed figures rather than open or incomplete parts.

Closure

Closure

Proximity Tendency to group together objects that are close to each other.

Proximity 3 columns 3 Rows

Similarity Tendency to group elements together that are similar to one another.

Similarity Columns Rows

Figure and Ground One form of perceptual organization in which we distinguish between an object and its background.

Figure and ground Vase or face?

http://www.gsw.edu/~gfisk/anim/gestalt.swf

Perceptual inference Perception based on sensory input and past experience. Mostly automatic & unconscious Fill in the gaps of what you sense!

Perceptual inference Auditory – hear a bark & assume it’s your dog Visual – driving over a hill, you ASSUME the road continues

We learn to perceive Learned – babies learn to recognize faces Interaction with our environment is necessary for the development of perception. (Kitten example) Influenced by -needs -beliefs -expectations Can’t just RIDE in the car…….you must DRIVE!

We learn to perceive Perceptual Set- You tend to believe/see what you expect heuristics lead to pre-judging (mis-judging) racism

External (monocular) cues Relative height Interposition Texture-density Light & Shadow Aerial & Atmosphere Motion parallax Linear Relative Motion

Relative Height: Farther objects appear smaller

Relative Height: Farther objects appear smaller

Interposition: Whole object closer than partial

Shadows: attached or cast? Give position clues

Shadows: attached or cast? Give position clues

Shadows: attached or cast? Give position clues

Texture –Density: Near objects = more detail

Texture –Density: Far objects = less detail

Aerial & Atmospheric: Bluing-far looks blue graying – pollution helps

Aerial & Atmospheric: Bluing-far looks blue graying – pollution helps

Aerial & Atmospheric: Bluing-far looks blue

Motion parallax As you move, NEAR objects seem to move more than FAR objects cars on a highway objects in a straight line of sight

Linear Perspective: parallel lines meet in distance

Linear Perspective

Accommodation The thickening or thinning of the lens to focus on objects near or far. Thickens for near objects. Thins for distant objects.

Relative motion If you look near, far things move with you. If you look far, near things move in the opposite direction. Look out your car window!

Relative motion

Internal / Binocular cues Convergence Retinal disparity

Convergence Eyes turn inward to look at an object. As the eyes turn inward, the muscles of the eyes send messages to the brain telling it the object is near.

Retinal Disparity / Binocular Fusion The two eyes see different images, the brain recognizes this, and then calculates distance. The two images are “fused” into one, creating one large, coherent image in your brain.

Constancy The tendency to perceive certain objects in the same even though light, angle, or distance may change. 3 Types Size/distance Shape/angle Brightness/color

Size constancy: all the same size but pilots know this better than you!

Shape constancy Perceive the shape of a known object as remaining unchanged although we may perceive it from different angles (different images cast on our retina)

Brightness constancy Perceive the brightness of an object as stable or unchanging regardless of a change in lighting. Objects in sunlight & shade

Illusions Illusions occur when we misperceive the true characteristics or properties of an object.

Illusions Spatial summation – A collection of individuals = a different whole

Sunday Afternoon on the Island of Grand Jatte by Georges Seurat (1884-1886)

Does our mind always accurately represent reality? -Ames room (p. 231)

Muller-Lyer Illusion

Subliminal Perception subliminal means literally “below the threshold.” -1957 movie theater experiment -subsequent experiments do NOT support this! -There IS evidence that we can detect subliminal information -Word Recognition experiment -Explanation for déjà vu?

Extra Sensory Perception Receiving info. From channels other than the “normal” senses -Clairvoyance: perception w/o sensory input -Telepathy: mind reading / thought transference -Psychokinesis: moving objects w/mind -Precognition: foretelling of events

Extra Sensory Perception - Ms. Cleo - ”6th Sense” - Yuri Geller - Spoon Bending - John Edward - ”The Amazing Randi” million $ challenge