Immediate and basic experiences generated by isolated, simple, stimuli

Physical stimulus/energy

objective/quantifiable/can be measured directly

One's interpretation of the sensation, giving the sensation meaning & organization

Psychological reaction

subjective/cannot be measured directly

Acquisition, storage, retrieval, and use of knowledge

e.g., A is first letter in apple, that is a red dress, that is a fire engine siren

Frequency=pitch (high frequency=high pitch)

Amplitude=loudness (high amplitude=loud)

Distance that light travels in once cycle (from peak to peak)

[image]

Bottom-up (data driven)

Top-down (conceptually driven)

continuum between sensation-perception-cognition

(distinctions not always clear)

basis for understanding all other areas of psychology

Basis for understanding behavior:

-cognitive psychology

-verbal bx/psych of language

-non-verbal behavior

-motivated behavior (appetite ctrl, S&P of taste is imp)

-atypical behaviors

ADHD, px detecting sensation and then perceiving it

Autism, not fully attending to sensation

Schizophrenia, perception in absence of sensation

-gerontology (aging process, taste deficits, can't hear high pitched sounds)

Theory is needed for perception not for sensation (which is objective and can be physically measured)

Types of theories:

-empiricism

-gestalt

-structuralism

-behaviorists/descriptive

-Gibsonian

-info processing

-computational approach

Perception is learned/acquired/experiential (not innate)

• developed in 1700s by george Berkeley
• perception happens when basic sensory expedriences are combined through learning 

Perception is innate, nativist approach, based on patterns

• developed in early 20th century
• configuration and patterns are imp
• criticized empiricists for not looking at relationship b/ parts of a stimulus
• whole is greater than sum of parts
• used poor methodology but were good observers of how parts fit together 

Opposite of Gestalt

-looked @ individual parts and measured the individual sensations

-described table by its individual parts

AKA descriptive

• developed in the USA from 1930s to 1960s
• just objectively described subject's overt behavior 
• not science bc they didn't say why it was happening, no underlying structure/reason

Focused on richness of the stimulus

• developed by James Gibson
• direct perception approach
• stimuli provide sensation, and that is all we need
• we directly perceive our environment from the rich information included in the stimulus

• Uses computer analogies & simulation
• emphasizes interdependence of sensation, perception, & memory
• more toward cog psychology than perception 

• Developed by David Marr (1982)
• perception requires problem solving
• tried to develop mathematical models that were consistent w/ physiological information

study of the relationship between sensation & perception

Started by Gustav Fechner

Measuring subject's sensitivity (ability to detect low intensity stimuli)

Uses bottom-up Processing

Classical psychophysics measures of detection/absolute threshold and recognition/identification thresholds are used

Detection AKA absolute

-intensity a stimuli must be to detect it 50% of the time

e.g., can you hear anything

recognition AKA identification

-intensity a stimuli must be for it to be recognized 50% of time

e.g., can you tell what noise this is (ask participant what it is)

Method of Limits

Method of adjustment

Method of constant stimuli

(always use stimuli with a certain level of uncertainty)

Inverse relationship

Low sensitivity=high threshold

High sensitivity = low threshold

eg cones-low sens, high illumination required, high threshold

rods-high sens, low illumination required, low threshold

X axis (abscissa): intensity of stimulus

Y axis (ordinate): probability of "yes" response

Not all or nothing, line will gradually increase

Trial: each stimulus presentation

Trial block: set of trials where each level of a stimulus intensity is used at least once

Present stimuli in sequential order (both ascending, star w/ lowest, and descending, start w/ highest)

detection threshold:between the 2 "limits" or change from Y to N responding (descend) or N to Y responding (ascend)-threshold is half way between limits

Average thresholds across all trial blocks to get final detection threshold

(always use ascend for  visual bc high intens affects future trials)

error of anticipation:know stimulus is about to become detectable or undetectable and change response prematurely

error of habituation: get accustomed to saying either Y or N and continue responding this way even after perception changes

On some trial somit presentation of lowest (ascending) or highest (descending) intensity to prevent subjects from counting

-can't "decide" which one they always perceive

• Subject (instead of experimenter), adjusts intensity
• used for continuous (all possible values included) variables only (can't use w/ discrete)
• Can be done very quickly
• determines approximate thresholds only
• High between-subject variance
• Errors aren't a proble bc fine adjustments can be made
• use adjustment for first approximation then pick measures for discrete test

• Stimuli presented in random order in each trial block
• constant set of stimuli presented constant # of times
• time consuming method
• eliminates errors (part can't form expectations)
• Provides most reliabledata

Determine threshold by adding up number of Yes at each value of stimuli, graph w/ stimuli value on X and proportion of Yes on Y (find 50% point which is threshold)

Problem w/ measuring sensitivity is it is always confounded w/ top-down processes (e.g. errors)

Can't hold thoughts (top down) constant, but you can hold sensitivity constant to measure top-down

Signal detection theory attempts to do that

• measures subject's decision-making strategy/ crietrion/beta (assesses top-down processing)
• subject's willingness to say 'yes' when they are uncertain whether the stimulus was presented
• uses the detection threshold so the part is uncertain and has to decide
• 1)holds sensitivity constant 2)manipulates criterion
• designed due to concerns about errors
• attempts to determine how participants decide what they detect

• holds stimulus intensity constant at the detection threshold
• tests subjects w/ equivalent acuity in the sensory modality being studied
• pretest subjects' detection thresholds to make sure they have the same sensitivity
• Ensures bottom-up isn't playing a role

d': Index of sensitivity: higher sensitivity = higher d'

Done by manipulating:

1) probability that a stimulus will be presented

2) Benefit/risk (eg get $5 everytime stimuli is dected corrected)

Increasing probability=more hits & more false alarms

Increasing sensitivity=less false alarms, same # of hits

Receiver Operating Characteristic Curve

Reciever=subject, operating characterstic curve=decision making or β

d' line is created by the hit rate in regards to false alarms

X=prob of false alarm, Y=prob of hit

d'=0=straight diagnol=guessing

curve farther towards upper left is better (higher) d'

Noise distribution: irrelevant stimulis, spontaneous or basal firing rates

Signal: relevant stimulus

Signal & noise distribution: noise distribution w/ relevant stimulus embedded into it (includes misses and hits)

noise distribution (includes correct rejections and false alarms)

higher d' = greater hit rate relative to false alarms

higher d'= greater distance between the peaks of the noise and signal distributions (less overlap b/ the distributions)

• Curves represent 100% of trials
• seperate curves for noise and stimulus trials
• Overlap of curves dependent on sensitivity (same distributions for ppl w/ same sensitivity)
• criterion line (marking if they said yes or no) changes based on probability they were told
• criterion line crossing signal+noise= to the right is a hit, left is a miss
• criterion line crossing noise=to the right is a false alarm, right a correct rejection

criterion line will move to the right (towards signal + noise distribution) if probability is lowered

so there will be less hits and less false alarms

Uses discrimination studies which try to find the smallest amount a stimulus must change to be perceived as just noticeably different

The amount is called the difference threshold: smallest change in a stimulus intensity that is required to produce a noticeable diff 50% of the time

Diff threshold=physical stimulus

jnd=psychological reaction

psychological reaction or perception of a different

-measured by the difference threshold

Use a standard stimulus (constant) and a comparison stimulus (varies)

find the point of subjective equality or the value of the comparison stimulus that the subject considers equal to the value of the standard stimulu

(intensity the participant can't discriminate from standard stimulus)

Counterbalance comparison w/ standard (order you present them)

e.g. Trial block (all comparison presented, counterbal)

trial 1= 4,S trial 2=S,1 trial 3=3,S trial 4=S,2 trial 5 5,S

• point of subjective equality is 3% of the solution (it was different on 50% of trials)
• JND=|.75|-|.25| / 2=(4-2)/2 = 1% of solution is JND
• you have to change the stimuli by 1% for it to be noticed

Weber's Law

Fechner's Law

Steven's Power Law

Ernst Weber

It's not the absolute size of the change but the relativesize of the change that is important

Weber's Law=change in intensity/intensity=k

predicts better for middle ranges of intensity than for higher or lower ranges

Based on Weber's Law        R=k log I

R=magnitude of our perceptual reaction

k=constant, multiplied by log of intensity

Log transformation is the exponent to which 10 must be raised to equal that number (reduces large numbers more than small numbers, eg log100=2, log 10000=4)

As intensity increases so does our psyc reaction, but intensity increases faster than our psych reaction

R=kIⁿ

more realistic bc it has a diff power function for diff stimuli

Exponent=1, linear (intensity increase=reaction inc)

Exponent<1, as intensity increases you get smaller and smaller response increases (sound/brightness)

Exponent >1, as intensity increases you get larger and larger increases in our responses (shock)

• determine a modulus (value assigned to standard stimulus)
• modulus is a yardstick to estimate magnitude of all other stimuli
• participant assigns other stimuli #s based on modulus

• Stevens found if exponent=1 increase in magnitude produces comparable increase in number assigned
• modulus (5) =3inches
• 6"=10, 12"=20, 24"=40
• exponent<1
• modulus (20)=10 units (u) of brightness
• 20u=25, 30u=33, 40u=33, 50u=36, 60=38
• exponent>1
• modulus(2)=10 shock units (u)
• 20u=4, 30u=30, 40u=80

comparison of stimuli across sensory systems

e.g. present visual sound wave of a given amplitude and participant perceives it as being a given loudness

-ask subject to draw a line that is as long as the sound was long and they are consistent

• union of the senses (synthesis of the sensory system)
• Stimulation of 1 sense triggers another
• Synesthetes are very atypical (1 in 2,000)
• most common is colored hearing
• also smelling hues or tasting shapes
• caused by a single X-linked gene
• Different from integrating senses which everybody dose

• give participants 100 words and told to say a color
• non-synesthetes: 37% matching answers at 1wk
• synesthetes: 92% matching answers at 1.5 yrs
• U=yellow to light brown
• I=white to pale gray
• O-white
• shows a systematic integration of senses in the brain (not random occurrences)

FMRI (measuring BOLD) and PET scans

-measure blood blow and brain activity

Found primary (area 17) and secondary (areas 18 & 19) in visual cortex and occiptal lobe don't have increases

Inferior temporal cortex in temporal lobe does show increase

-higher level visual processing and perception

This supports that no sensation is occuring but perception is

Electromagnetic radiation: waves produces by electrically charged particles

We see between 400 and 700

waves<400 are too short, >700 are too long

Perception determines reality not sensation

anatomy and physiology guide reality

perception can occur w/out sensation (optical illusions)

Nanometer (nm)=1 billionth of a meter

(mm=.001, micrometer=.000 001, nm=.000 000 001)

meter=39.37inch so nm=.00000003937nm

• Wavelength=distance light travels per cycle (peak to peak)
• Purity=number of wavelengths present
• amplitude (intensity)=height of light wave

wavelength is the sensation

perception is the hue

color is an incorrect substitution for hue

violet=440

blue=470

green=540

yellow=570

orange=640

red=670

One wavelength=purity, adding waves decreases purity

if all wavelengths are the same it is a pure color and we perceive it as being saturated

Sensation:670nm, purity/ Perception:pure red, saturated

Saturated is incorrectly referred to as brightness

White light is incredibly unsaturated

(intensity) height of wave

Sensation:amplitude, Perception:brightness

Brightness is incorrectly called light or dark

High amplitude=brighter=light red

lower amplitude=less bright=dark red

Sclera: surrounds eye, joins w/ cornea, filled w/ fluids to keep spherical shape

cornea: transparent membrane in front of eye

-does 2/3 of light bending to focus on retina

Iris: pigmented set of muscles (2 sets-1 to constrict and 1 to dilate pupil)

-dilates when dark to get light on peripheral of fovea

Pupil: orpheus (hole) that gets light to the fovea

Lens: smart light bending, all the fine tuning to get light exactly on fovea

-behind cornea, pupils & iris

Extraocular muscles:lets us move our eyes, must be coordinated between two eyes

Ciliary muscles: connected to lens by zonules of zinn

contracts or relaxes to change shape of lens

• astigmatism: distortion of cornea, refracts light wrong
• acquired: big px, environmental cause (injury)
• congenital: born w/ it, pear shape, fixable
• conjunctivitis: inflamation of conjunctiva (pink eye)
• conjunctiva: pink mucus membrane (highly vasculized) connects lid to eye so stuff can't get behind eye
• cataract: cloudy lense
• lots of diff reasons, causes 50% of blindness
• surgical removal and replace w/ intraocular lens substitute
• Presbyopia: lens keeps growin, eventually old ppl can't thicken lens enough to see near objects and become hypermetropic
  

• between cornea and lense
• filled with aqueous humor which gets Oxy to eye bc you can't have blood bc light can't pass through it
• Aqueous humor also maintains eye's shape
• imp for light bending
• humor constantly replaced, drained out of canal
• glaucoma occurs when canal to drain humor is blocked (tx by lazor surgery & meds)
• tested using tonomoetry (test of eye pressure)

• Posterior chamber (larger back of eye) is filled with vitreous humor
• gelatin substance, keeps shape and gives some oxygen (some comes from blood)
• humor has floaters from erythrocytes/red blood cells (strains of material, black dots in vision)
• choroid: highly vasculized, gets most of oxy to retina
• between sclera and retina
• detached retina: seperation of choroid & retina doesn't get oxygen & nutrients

Transduction takes place in the retina by photoreceptors

Macula Lutea (2mm) in center of retina (mostly cones)

Fovea (.3mm) in center of macula lutea (only cones)

Macular Degeneration: leading cause of blindness

Dendrites: receive input from other neurons

ganglion: collection of cell bodies

nerve: collection of axons or fibers

Ganglion cells: collection of cell bodies from which the optic nerve extends

Optic Nerve: 2nd cranial nerve, collection of axons extending from ganglion cells

composed of one layer of protein between 2 lipid layers

called white mater (fat is white)

facilitate conduction

Ganglion cells are in posterior chamber

Axon of ganglion cells exit at the optic disc and become the optic nerve

Optic nerve is the bundle of neurons that carry information away from the retina

Optic disc-no photoreceptors, blind spot

direct relation b/ convergence & sensitivity

inverse relation b/ convergence & acuity

inverse relation b/ acuity & sensitivity

• convergence allows for high sensitivity bc multiple signals can summate to reach threshold
• convergence prevents acuity bc you can't actually tell where signal came from
• (cones w/ little convergence you know if it fires where it came from, but it might not fire all the time bc no summation)

• Rods, rhodopsin (not broken down, all the same) 
• 496 nm
• Cones (3 different opsin parts)
• long (L-cone), 560 nm
• Medium (M-cone), 530nm
• Short (S-cone), 420 nm
• each photopigment has a maximum absorption
• what they are most sensitive to in terms of wavelengths
• each one has a range around it (normal curve)

• Rhodopsin is the photopigment that tranduces light energy
• in dark Rhodopsin is stable
• in light it breaks down into 2 parts
• Opsin (larger part) has 4 different types
• Opsin makes diff photopigments in cones
• Retinal is the smaller part that is the same in all cells (vitamin A component)
• Break down effects G-proteins
• G-proteins inhibit Na+

Hyperpolarization

-35mV is resting

-70mv is hyperpolarization

M & Lcones-> on/off midget bipolar->midget ganglion

-Midget cells are small bc there isn't much convergence

-light on activates M&L, sends input to on midget bipolars

-light off activates off midget bipolar

-both on & off midgets go to midget ganglion

S cone ->on/off midget bipolar->small bistratified ganglion cells (bistratified means 2 layers)

-very few S cones exist (90-95% are M or L)

-there is some convergence but there are few S cones

-have diffuse dendrites on bipolar

≤50 rods ->rod bipolar->amacrine cells (act laterally)-> parasol ganglion cells

in a few rare cases ≤10 cones go to diffuse conce bipolars then to parasol ganglion cells

But we should associate parasol ganglions with rods for this class

Resting membrane potential is -70mV (based on distribution of ions across cell membrane)

Types of ions (electrically charged particles: anions=negative,  cations=positive

Depolarization: more positive due to

-ions flow down concentrationg gradient

-ions more attracked to unlike charges

(action pot for depolarization to +40mV)

• A- are too big to move out bc of semi-permeable membrane
• NA+ voltage channels keep them out at resting
• NA+ and CL- stay because concentration gradient balances out charges

• Depolarizes to +40mV
• voltage-gated Na+ channels open and Na+ enters cell
• action potential happens
• refractory period: ions are re-establishing resting pot

Single cell recording of ganglion cells

-put a microelectrode (1mm) into a single cell

basal firing rate: is the chronic/spontaneous act pot (50/sec) in the absence of any stimulation

-compare basal to firing in presence of stimulation

Antagonistic center-surround receptive fields

on center/off surround: light in center of receptive field excites cells light in surround inhibits it

-center is more powerful then surround

photoreceptors that the ganglion responds to

(find receptive field by putting line in diff places and measuring ganglion activity)

Midget cells maintaing firing the whole time light is on, parasol get a burst that doesn't last

ipsilateral: same side

contralateral: opposite side

mesial/medial: middle

lateral: at the side

chiasm: decussation/crossover

Nucleus: collection of cell bodies in  (PNS-Ganglion)

Tract: collection of axons/fibers (PNS-nerve)

Geniculate: bent like a knee (what LGN looks like)

fibers of ganglion cells cross over

-really impr for binocular vision

-coordinates inform from 2 eyes diff visual fields

No synapses at the optic chiasm

Optic nerve changes to optic tract at this point just because it goes from PNS -> CNS

lack of coordination between muscles in the 2 eyes

-messes up binocular vision

12 layers (6 main, 6 sub)

• 1 & 2 (ventral) are from M pathways/parasol/rods
• 3,4,5,6 (dorsal) are from P pathway/Midget/M&L
• below each is a layer from K/small bistratified/S
• 1,4,6 & Ks beneath get input from contralateral eye
• 2,3,5, & Ks beneath get input from ipsilateral eye

retinotopic: cells near each other on LGN get info from photoreceptors close to each other

LGN cells have center-surround receptive field but surround is more powerful than in ganglion cells (all lit would have less activation)

only 10% of LGN input is from retina (other info comes in for integration)

• Left eye
• left visual field hits right part of eye and goes contralateral to right hemisphere
• right visual field hits left part of eye and goes ipsilateral to left hemisphere
• Right eye
• left visual field hits right part of eye and goes ipsilateral to right hemisphere
• right visual field hits left part of eye and goes contralateral to left hemisphere
• reason optic disc is in the left visual field for R eye and right visual field for L eye

primary visual cortex=area 17=striate (striped) cortex=V1

secondary visual cortex=area 18 & 19=nonstriate cortex=extrastriate cortex=V2-V5

layer IVc of the primary visual cortex

-other layers of primary visual cortex don't have center-surround receptive field (only IVc, where LGN is)

primary visual cortex sends info it gets from LGN on to secondary visual cortex

ove-representation of info originating in fovea

-occurs mainly im primary visual cortex

-fovea is small but 1/2 of visual cortex gets info from fovea

Most ganglion go to LGN but 10% go to superior colliculus

-receives input from visual, auditory,and sensory systems

-plays a role in control of eye movements

-ganglion here have large dendritic fields (might be from K or rods)

Hubel and Wiesel

-put electrode into each subsequent layer (deeper) and assessed response to diff stimuli

-then moved electrode over .05 mm and repeated

cells respond the most to a certain orientation, as you get closer to that orientation firing increases

column:vertical set of cells that have best response to the same line (break at IVc bc of cent/surr structure)

-cells in subsequent columns make best response to a line rotated 10^o from previous column's best line

hypercolumn-sequence of 18-20 adjacent columns that make up a full cycle of line orientations

• simple cells: response best to lines and edges
• complex cells: respond best to moving stimuli
• larger receptive fields bc they have to be big enough that the stimuli can move around in it 
• end-stopped cells: best if stimulus is all in receptive field
• can be either simple or complex cells
• important in detecting boundaries
• blobs: convey color info (cone info, P/K system)
• not sensitive to line orientation
• interspersed w/in hypercolumns
• interblobs: occupy space between blobs
• sensitive to line orientation
• not sensitive to wavelength, no color
• get info that starts from cones (P system)

1/3 of brain is comitted to visual system

-vision is primary sensory system for cognition and intelligence bc of large amount of integration

Gross: studied response of inferior temportal cortex to a lot of stimuli

-barely responded to anying, til he waved goodbye and it fired

inferior temporal cortex is related to perception

Agnosia: loss of ability to recognize a sensory stimulus

-can happen in any sense

-detect stimuli but don't know what it is

-can still describe the parts

visual agnosia: inability to recognize familiar objects by sight

Prosopagnosia: inability to recognize other people or one's own face