PSYC230 Exam 1

what is sensation and perception?

sensation: registration of stimulus on sensory receptors

perception: creating conscious perceptual experience from sensory input

what is neural transduction? Include receptors, transduction, and neural repsonse

neural transduction is converting a stimulus into an electrochemical signal:

1. first receptors detect and absorb stimuli

2. then transduction converts this into an electrical signal

3. then it converts it into a neural response (electrochemical)

what is phenomenology and example

subjective and internal experience/perception of the world; feeling of what it is like to have an experience

-e.g. my perception of blue different from someone else’s

Aristotle and five senses

-sight, hearing, taste, touch, smell

-argued perception happens directly in physical organs & no sixth sense existed

Thomas Young (1773-1829)

-colors detected by 3 kinds of nerve fibers

Johannes Mueller (1801-1858), argument and example

doctrine of specific nerve energies: argued that it is specific neurons activated that determine that particular type of experience

-e.g. optic nerve activation leads to visual experience)

Hermann Von Helmholtz (1821-1894)

-constructivist approach: perception is constructed from both senses and cognitive processes

-we use unconscious inference/incorporare preexisting knowledge in perceiving/constructing

-first person to measure the speed of neural transmission (action potential)

-three basic color receptors (trichromatic theory of color vision/Young-Helmholtz theory of color perception): perception is based on three primary colors, red, blue, and green

Edwald Hering (1834-1918)

-colors are perceived through 2 pairs of opposing colors (red vs green, yellow vs blue, as opposed to color trichromacy)

-everything is in the stimulus (the stimulus is sufficient enough info to grasp the structure of the perceived world)

-influenced Gestalt psychology/Gibsonian view

Weber’s law

just-noticeable difference (JND) between two stimuli is related to the magnitude of strength of the stimuli

large vs small stimulus JND + examples

-larger stimulus values have larger JNDs (e.g., turning off the light completely in a lit-up room)

-smaller stimulus values have smaller JNDs (e.g. lighting a tiny candle in a corner of a room when the light is off)

Gustav Fechner (1801-1887)

father of psychophysics: the study of the relation between physical stimuli and the perception they elicit

Fechner’s law

sensation is a logarithmic function of physical intensity (X-axis: physical intensity, y-axis: perceptual intensity)

Gestalt psychology main principle

the whole is larger than the sum of its parts

Gestalt laws

• law of proximity

• law of common fate

• law of closure

• law of similarity

• law of good continuation

law of proximity

brain perceives items close in proximity as collective unit, whereas items far apart are viewed as seperate

law of common fate

brain groups together visual elements that move, point, or change direction in the exact same way or at the same time

law of closure

brain fills in gaps in incomplete visual imagine to perceive it as a whole unified object

law of similarity

brain groups items that share visual traits into a unified pattern or single group

law of good continuation

human eye follows a line, curve, or smooth path, preferring continuous movement over abrupt changes

Gibsonian/Direct perception

-all info you need to understand an object is given by the object itself

-i.e. environment provides all necessary info for us to perceive world accurately without needing mental calculations or past experiences

information processing approach

-like a computer; mind computes similarly

-mind is a sequence of information processing stages (boxes)

computational approach

-advanced version of the information-processing approach

-all boxes like in info processing approach, but instead of happening at one time, info can flow between boxes and happen at the same time

brain and its 4 lobes/two other parts/main senses

frontal: taste/smell

parietal: touch

temporal: hearing

occipital: vision

brain stem: connects to body

purple area: lower brain cerebral cortex/cerebellum

LOOK ON NOTES FOR WHERE EACH PART IS (P. 5)

cortexes associated with each lobe and their function

frontal: taste/smell

parietal: touch; somatosensory cortex: receives info from receptors in skin

temporal: hearing; auditory nerve: receives info from ears

occipital: vision; visual cortex: receives info going into optic nerve

Techniques used to study the brain (4)

-microelectrode

-neuropsychology

-electroencephalography (EEG)

-neuroimaging (functional MRI/fMRI)

microelectrode

take out little part of skull, implant microelectrode in brain, see how neurons react to tones from microelectrodes

neuropsychology

studies relationship between brain damage and behavior alterations

agnosia

occipital lobe damage causing inability to recognize objects

prosopagnosia

inability to perceive faces (cant tell grandma is grandma, but can identify features)

Electroencephalography (EEG)

cap on person’s head, electrodes record neuron activity/wavelengths (REVIEW NOTES)

fMRI

studies where things are happening in the brain, out person in scanner, many pictures taken of brain, can see which areas of brain are more active (REVIEW NOTES)

psychophysical scale

scale where people rate their psychological experiences as a function of the level of a physical stimulus

absolute threshold

minimum amount of stimulus to still be detetced

method of limits

-ascending series and descending series, presented in orderly fashion by the experimenter

-intensity 10-1, multiple trial, can you see it yes or no?

-Crossover between last yes (detection) and no (no detection)

-take crossover points and average them = the threshold

-two-point touch threshold: minimum distance along skin at which two touches are perceived as two touches and not one

method of constant stimuli

-experimenter presents observer with a set of stimuli in random order, some above, some below threshold

-uses a psychophysical curve

method of adjustment

-as in method of limits, but observer controls levels of stimulus and adjusts it to be at the perceptual threshold, increases or decreases stimulus until it feels just at detectable level

-lower threshold = higher sensitivity

sensitivity

ability to percieve a stimulus, inversely related to threshold

magnitude estimation

-participants judge and assign numerical estimates to the perceived strength of stimulus

-administered by experimenter

Steven’s power law

ON NOTES P. 9

catch trials and their use

catch trial is a trial in which the stimulus is not presented, so you can see if someone is false reporting (inaccurate results mitigated)

Signal detection theory:

-Criterion

-d prime

-Hit

-Miss

-False Alarm

-Correct Rejection

ON NOTES P. 10

changes in criterion

P. 10 NOTES

differences in sensitivity (d prime)

ON NOTES P. 10

types of touch receptors (6)

• thermoreceptors

• mechanoreceptors

• kinesthetic receptors

• nociceptors

• itch receptors

• pleasant/gentle touch receptors

thermoreceptors

detect temperature

mechanoreceptors

detect mechanical displacements of the skin

proprioception vs kinesthesis

proprioception: unconscious perception of movements/positions of our limbs in space (includes vestibular sense and kinesthesis)

-alcohol consumption affects this

kinesthesis: conscious awareness and perception of bodily movements

muscle spindles

senses when muscles contract and lengthen, and different neural signals are transduced in the spindles, giving info to brain about muscle length and action

joint receptors

senses information regarding the angle of out joints, how far limb is stretched and whether it can stretch further before it must be contracted, and sends it to the brain

golgi tendon organs

provides feedback as tp how much force has been applied to that muscle, measures the force of a muscle’s contraction

vestibular sense

sense of balance/movement felt thru inner ear

kinesthetic receptors

-detection of the location and position of body parts through receptors in the muscle spindles, golgi tendon organs, and joint receptors

-Part of proprioception

nociceptors

detect pain sensations

itch receptors

detect itch

gentle touch/pleasant touch receptors

involved in pleasure/bonding

4 types of mechanoreceptors + where they are located

-located in dermis

-SAI

-SAII

-FAI

-FAII

receptive field sizes and meaning

smaller receptive fields: SAI and FAI = dense mechanoreceptors = higher sensitivity

larger receptive fields: SAII and FAII = dispersed mechanoreceptors = lower sensitivity

Slow adapting and fast adapting meanings

slow adapting: SAI and SAII = sustained response when there is contact, lasting the whole time (e.g.

fast adapting: FAI and FAII = fast response when the stimulus onsets and offsets (e.g. when mosquito lands on skin)

SAI

-slow adapting, smaller receptive field

-detection/perception of patterns and texture

-e.g. holding water bottle steadily

SAII

-slow adapting, larger receptive field

-detecting stretching of the skin/if fingers shaped properly

-e.g. holding a water bottle tightly and positioning hands correctly to do so

FAI

-fast adapting, smaller receptive field

-respond to low frequency vibrations

-e.g. detecting water bottle slip out of hand —> adjusts grip

FAII

-fast-adapting, larger receptive field

-when objects make contact with out skin, or when object you’re holding makes contact with something

-e.g. you tap the cap of water bottle or it falls on the ground

When feeling shape of your key in your backpack, the 1)___ detects it’s pattern. Then, shaping fingers to grasp the key properly uses 2)___. Then, to get the key in the lock, 3)___ helps you increase grip force so that the key does not slip. Lastly, 4)___ tells you when the key has hit the end of the keyhole/

1. SAI

2. SAII

3. FAI

4. FAII

Ian Waterman

-lacked kinesthetic sense and in the dark he didn’t know where his body was

-without peripheral feedback from kinesthetic receptors, his brain could not coordinate movements

thermoreceptors

-ability to sense temp. changes on skin

-sensory receptors signal info about temp

-hot fibers and cold fibers fire at intermediate temps

-hot fibers fire when temp on skin ruses above 36C/97F

-cold fibers fire when temp on skin measures below 30C/86F (e.g. touching icecream)

-thermoreceptors respond to 17C/63F to 43C to 109F, and skin temps below or above this experienced as pain

under extreme cold conditions, cold fibers can ___ firing, and heat fibers can produce a __________

stop firing; burning cold effect

pain

perception and unpleasant experience of actual or threatened tissue damage

neuropathic pain + examples

-chronic pain causes by damage, injury, or malfunction of the nervous system, and related to nociceptors

-diabetes, carpal tunnel syndrome, cancer

inflammatory pain + examples

-physical discomfort/heightened sensitivity when immune system reacts to tissue damage, infection, or irritation

-e.g. sprains, arthritis, autoimmune diseases

empathy pain happens how

neural circuits, mirror neurons, etc.

emotional pain can cause _____ despite there being no _____

physical symptoms; physical cause

A-delta fibers vs C-fibers

A-delta fibers: myelinated, fast nociceptors responding to heat and pressure (stinging feeling of pain)

C-fibers: nonmyelinated, slower nociceptors responding to extreme heat, cold, pressure, and toxic chemicals (throbbing pain, might be delayed)

Melzack and Wall (1988) study: no pain sensation

-people without nociceptors tend to die very young

-pain hurts but it protects us

Two pathways to the brain

somatosensory cortex

in parietal lobe of cerebral cortex devoted to processing information coming from the skin senses

somatotopic map

feature whereby skin on body maps onto the surface of the primary somatosensory cortex in a systematic way

-REVIEW SLIDES P. 15

homunculus

-illustrates how many neurons represent the different body parts in the somatosensory cortex

-sensitivity determined by receptor density, not physical size

phantom limb syndrome

-some amputees feel their missing limb

suborganization of the somatosensory cortex

“what” channel

“where” channel: correcting grip