CHAPTER 8: SENSATION AND PERCEPTION - PowerPoint Presentation

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CHAPTER 8: SENSATION AND PERCEPTION

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SECTION 1: SENSATION

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WHAT IS SENSATION?

Def

: what occurs when a stimulus activates a receptor

Stimulus

: an aspect of or change in the environment to which an organism responds

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SENSATION CONTINUED

Perception

: organization of sensory info into meaningful experiences

Psychophysics

: study of the relationships between sensory experiences and the physical stimuli that cause them

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THRESHOLD

Absolute threshold

: the weakest amount of a stimulus that a person can detect half the time

Humans have a very limited range

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SENSORY DIFFERENCES

Difference threshold

: the smallest change in a physical stimulus that can be detected between 2 stimuli

Just Noticeable Difference (JND)

: the smallest increase or decrease in the intensity of a stimulus that person can detect

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WEBER’S LAW

For any change in a stimulus to be detected, a constant proportion of that stimulus must be added or subtracted

A.K.A.: Weber-Fechner Law

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SENSORY ADAPTATION

Senses are tuned to change

Senses adapt to a constant level of stimulation

Necessary to ignore mundane

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SIGNAL-DETECTION THEORY

Def

: the study of people’s tendencies to make correct judgments in detecting the presence of stimuli

Radar operator

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PROCESSING STIMULI

Preattentive

process

: extracting information automatically

Attentive process

: procedure that considers only one part of the stimuli presented at a time

Stroop

Interference Effect

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SECTION 2: THE SENSES

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VISION

Most studied sense

Pupil

: opening in the iris that regulates the amount of light entering the eye

Lens

: flexible structure that focuses light on the…

Retina

: innermost coating of the back of the eye, containing light sensitive receptor cells

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VISION CONTINUED

Cones

and

Rods

: light receptors in the retina; convert light energy into neuronal impulses

Cones: color

Rods: night vision

Optic Nerve

: the nerve that carries impulses from the retina to the brain

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COLOR DEFICIENCY

Affects 8% of American men; <1% women

Dysfunctional cones

Red-green

Yellow-blue

Total deficiency: see in black and white

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BINOCULAR FUSION

Def

: the process of combining the images received from the two eyes into a single, fused image

Retinal Disparity

: the differences between the images stimulating each eye

Essential for depth perception

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NEARSIGHTEDNESS

Eyeball is longer than normal

Objects focused at a point in front of the retina

See objects that are near, but not far

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FARSIGHTEDNESS

Eyeball is too short

Objects focused slightly behind the retina

Distant objects are clear, near objects are not

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HEARING

Sound waves: vibrations in the air

Loudness determined by

amplitude

(height) of waves

Strength determined by decibels

>

110 decibels damages hearing

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HEARING

Pitch

depends on sound wave frequency (rate of vibration of medium through which wave travels)

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PATH OF SOUND

Outer ear (

pinna)

receives waves

Auditory canal vibrates which vibrates the ear drum

Middle ear: 3 tiny bones---hammer, anvil, and stirrup

Inner ear: cochlea---liquid moves, tiny hairs detect motion, translate into neuronal input and sent to brain by the

Auditory nerve

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DEAFNESS

2 types:

1)

Conduction deafness

: hindered physical motion in the outer or middle ear

Helped with conventional hearing aid

2)

Sensorineural

deafness

: damage to the cochlea

Helped with cochlear implant

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BALANCE

Vestibular system

: 3 semicircular canals that provide the sense of balance, located in the inner ear and connected to the brain by a nerve

Fluid in canals moves

Hair cells translate motion

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SMELL

Chemical sense

Gaseous molecules contact smell receptors

Olfactory nerve

: carries smell impulses from the nose to the brain

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TASTE

5

primary tastes:

1) Sweet

2) Sour

3) Bitter4) Salty

5) Umami (savory, meaty)

Combination of these creates flavor

Taste is more determined by smell

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SKIN SENSES

Densely bundled nerve endings create sensitivity to pressure

Some are sensitive to hot and cold

Pain results from many different stimuli

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PERCEPTIONS OF PAIN

Sharp, localized pain immediately after injury

Dull, generalized pain later

Gate control theory of pain

: shifting attention away from pain can lessen its effects

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BODY SENSES

Kinesthesis

: the sense of movement and body position

Cooperates with vestibular system and vision

Receptors in and near muscles, tendons,

and joints

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SECTION 3: PERCEPTION

The way we interpret sensations and organize them into meaningful experiences

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GESTALT

Def

: the experience that comes from organizing bits and pieces of info into meaningful wholes

Trying to identify principles the brain uses in building perception

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GESTALT PRINCIPLES

1) Proximity

2) Continuity

3) Similarity

4) Simplicity

5) Closure

If elements are close to one another or similar, we perceive them as one set

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FIGURE-GROUND PERCEPTION

The ability to discriminate

btwn

a figure and its background

Shows we can perceive in more than one way

Works with sound as well

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PERCEPTUAL INFERENCE

Filling in the gaps in what our senses tell us

Largely automatic and unconscious

Depends on experience

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LEARNING TO PERCEIVE

Influenced by needs, beliefs, and expectations

If we want something, we’re more likely to see it

Perceptual set

: twisting truth to fit our own belief system

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SUBLIMINAL PERCEPTION

Subliminal messages

: brief auditory or visual messages that presented below the absolute threshold

Not really effective

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DEPTH PERCEPTION

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MONOCULAR DEPTH CUES

Can be used with a single eye

Relative height

: objects further away are higher on your visual plane

Interposition

: overlapping

Light and shadows

: brightly lit objects are closer

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MORE MONOCULAR CUES

Texture-density gradient

: close objects have more detail

Motion parallax

: the apparent movement of stationary objects relative to one another that occurs when the observer changes position

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MORE MONOCULAR CUES

Linear perspective

: parallel lines converge in the distance

Relative motion

: near objects appear to move in the opposite direction that you do; far objects seem to travel with you

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BINOCULAR DEPTH CUES

Depend on movement of both eyes

Convergence

: eyes turn inward when looking at nearby objects

Retinal disparity

Large disparity means close; small means far

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CONSTANCY

Def

: the tendency to perceive certain objects in the same way regardless of changing angle, distance, or lighting

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ILLUSIONS

Def

: perceptions that misrepresent physical stimuli

Happens when perceptual cues are distorted so our brains cannot correctly interpret space, size, and depth cues

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EXTRASENSORY PERCEPTION

Def

: (ESP) an ability to gain info by some means other than the ordinary senses

4 types:

1) Clairvoyance: perceiving w/o sensory input

2) Telepathy: mind reading

3)

Psychokinesis

: move things with your mind

4) Precognition: foretell events

I’m a big idiot who likes to rob people of their money by preying on their personal loss