Psychology: Unit 5-Sensation and Perception

Sensation: Your window tot he world

Perception: Interpreting what comes in your window

Sensation: The process by which our sensory receptors and nervous system receive stimulus from the environment


Bottom-up vs. Top-down Processing

Bottom-up Processing: Begins with the sense receptors and work up to the brains integration of sensory information
Top-down Processing: Information processing guided by higher level mental processes

Absolute Threshold: The minimum stimulation to detect a stimulus 50% of the time
Difference Threshold: The minimum difference that a person can detect between two stimuli

• Also known as "Just Noticeable Difference"

Weber's Law: The idea that to perceive a difference between 2 stimuli, they must different by a constant percentage; not a constant amount

Signal Detection Theory: predicts how we detect a stimulus amid other stimuli

Sensory Adaptation: Decreased responsiveness to stimuli due to constant stimulation

Selection Attention: The focusing of conscious awareness on a particular stimuli

Cock-tail-party-Phenomenon: Describes the ability to focus one's listening attention on a single talker among a mixture of conservation and background noises, ignoring other conversations

• Form of selective attention

Vision: Our most dominating sense

Visual Capture

• Phase One: Gathering light
• Short wavelength =high frequency (bluish colors, high pitched sounds)

• Long wavelengths=low frequency (reddish colors, low-pitched sounds)

• The height of a wave gives us its intensity (brightness)
• The length of the wave gives is its hue (color)
• ROY GBIV
• The longer the wave, the more red
• The shorter the wavelength the more violet

• Phase 2: Getting the light int he eye

Transduction: Transforming signals into neural impulses

• Information goes from the senses tot he thalamus then to the various areas in the brain
• Changes from one form of energy to another
• Ex. Light energy to vision, chemical energy to small and taste, sound waves to sound

Color Vision: Young Helmholts Trichromatic (3 color) Theory

• 3 types of cones
• Red
• Blue
• Green
• These 3 types of cones can make millions of combination of colors
• Most color blind people simply lack receptors cells for one or more of these primary colors

Opponent-Process Theory: The sensory receptors come in pairs

• Red/Green 
• Yellow/Blue
• Black/White
• If one color is stimulated, the other is inhibited

Hearing

• 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 of the sound

Transduction in the ear

• Sound waves hit the eardrum then anvil, then hammer, then stirrup, then the oval window
• Everything is just vibrating
• Then the cochlea vibrates
• The cochleas is lined with nerves called basilar membrane
• In basilar membrane there are hair cells
• When hair cells vibrate, they turn vibrations into neuron impulses which are called "organ of Corti"
• Sent then to the thalamus up auditory nerve

Place Theory and Frequency Theory

Place Theory: Different hairs vibrate in the cochlea when there are different pitched

• So some hairs vibrate when they hear high pitch and others vibrate when they hear low pitches

Frequency Theory: All the hairs vibrate but at different speeds

Deafness

• 2 Types
• Conduction deafness
• Something goes wrong with the sound and the vibration on the way tot he cochlea
• You can replace the bones or get 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

Small and Taste 

Studies together because of:

• Sensory Interaction: The principle that one sense may influence another

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

Umami: Flavorable, meaty, savory, taste

Monocular Cues

Interposition: If something is blocking our view, we perceive it as closer

Relative Size: If we know that 2 objects are similar in size, the one that looks smaller is farther away

Relative Clarity: We assume hazy objects are farther away

Texture Gradient: The closer it looks, the closer it is

Relative Height: Things higher in our field of vision look farther away

Relative Motion: Things that are closer appear to move more quickly

Liner Perspective: Parallel lines seem to converge with distance

Light and Shadow: Dimmer objects appear farther away because they reflect less light

Motion Perception

• We judge mostly by the size of the object

Phi Phenomenon: An illusion of movement created when 2 or more adjacent blink on and off in succession

Perceptual Consistency: Perceiving objects as unchanging even as illumination and retinal images changes