conscious sensory experience which occurs when physical signals are transformed into the experience of seeing, hearing, etc.

orgain of perception = the brain

1. environmental stimulus- all the enviornment that we can potentially percieve

2. attended stimulus - what becomes the center of attention in the environment (changes a lot)

3. stimulous on the receptors - image on retina is transformed into electrical signals via transduction

4. transduction - when energy in the env. is transformed into electrical energy

5. processing - operations that change the electrical responses of neurons

6. perception - conscious sensory experience transformed in the brain

7. recognition - ability to place an object in a category

8. action - motor activities human takes afterwards

mainly depends on how they go through the perceptual process

- depends on environment, their knowledge of the environment, the time of day, physical properties of the person (any disorders they may have), what they focus on

duck/rabbit image

see two perceptions from one pic (but only see one at a time)

physical stimulus to identification/perception

absolute threshold

difference threshold

magnitude estimation

smallest difference between 2 stimuli that can be detected

JND = just noticeable difference

gustav fechner

method of limits, constant stimuli, adjustment, and magnitude estimation

experimenter presents stimulus in ascending or descending order (based on intensity) in a stepwise motion to determine threshold

fastest, but least accurate

ex: presents a light at varying intensities, and asks when they can detect it

continuous adjustment by the subject until the stimulous is barely detectable - used mostly for difference thresholds

ex: volume in a car until audible

experimenter presents 5-9 stimuli with different intensities in random order over several trials - the threshold is the the one percieved 50% of the time

ex: image of smiley face, display 8 intensities 12 times in random order and see how they scale

webers law

JND = kS

k = constant (different for different stimuli)

S = intensity of standard

by stanley stevens

based on a standard stimulus (if this light is a 10, what is this one?)

P = kSⁿ

k and n are constants

s is stimulus intensity

as intensity is increased, the magnitude increases but not as rapid as intensity

mostly for light

as intensity is increased, the perceptual magnitude increases more than intensity

mostly for pain

parts of neuron and function

[image]

1. axon - fluid that conducts electrical signals and sends signal, ending in an axon terminal

2. cell body - keeps the cell alive

3. dendrites - branches from cell body to recieve signals

4. myelin sheath - white colored, encases the axon and it makes the impulse go faster by jumping the nodes

5. schwann cell - on the myelin sheath, function?

6. nodes of raniver - gaps btw. myelin

bipolar - interneuron

unipolar - sensory

multipolar - motor

pyramidal (only in cerebellum)

outnumber neurons 10:1

structurally supoort neuron, but not involved in impulses

sulci - crevase in brain

gyri - protruding part of the cortex

parts of cerebral cortex and functions

frontal lobe

temporal lobe - hearing

occipital lobe - vision

parietal lobe - skin senses (mvmt., orientation, etc)

change in the charge of the cell/potential membrane, sending the signal down the neuron (goes from - 70 to + 30)

1 - resting state

intracellular = high concentration of potassium K+ and negative proteins

extracellular = high concentration of sodium Na+

makes the inside more negative

2- depolarizing phase

sodium channel opens up causing an influx of sodium ions (turning the inner cell positive)

3- repolarizing phase

potassium channel opens up causing an outflux of potassium ions (turning inner cell back neg)

4-return to resting

sodium/potassium pump returns the cell to regular resting state (3 sodium out and 2 potassium in)

sensory (have an inputted stimulus) afferent neurons to integrative (in the brain) inter neurons to motor output efferent neurons

also used to maintain homeostasis

different stimuli appear differently based on how the visual system is set up

for example, we see color, snakes see infrared...scamper the bunny appears very differently in both circumstances :)

visual system pathway

EYE ONLY

Visual Pathway

Photoreceptor onward

Visual Pathway

brain onward

(retinogeniculostriate pathway)

RODS!!!!!!!!

weeee love you

main funcion: sensitivity and movement

rods are all over the retina except in the fovea

more rods than cones ~120,000,000

contains rhodopsin

CONES

the straight up ballllas :)

main function: color and detail vision (acuity)

3 types of cones and proteins in them (not important details)

located in fovea and retina, more in periphery, but only cones in fovea

Visual Transduction

light adaption

isomerization: when the retinal absorbs a photon of light and it changes shape (cis to trans) in rhodopsin, sends signal to the brain, opsin falls, converts back to cis

when in trans- cant absorb light for a while

called bleaching of rhodopsin

Transduction

Dark Adaptation

cones adapt quicker than rods in the dark, but arent sensitive

as you are in the dark more you use rods more (called the rod/cone break)

therefore, your seeing in the dark becomes better and more sensitive

structural organization of cones and rods

(convergence)

rods have higher convergence onto one ganglian cell therefore they are more sensitive to firing from covering a larger area on the retina, however cones are paired with one gangian cell, therefore becoming more accurate/greater acuity because they can detect location easier

periphery cones: 1:6

fovea cones: 1:1

rods: alot to 1

there are smaller receptive fields in the center of the eye (fovea) compared to the periphery

hermann grid example

you dont see things as well in periphery because there is more inhibition because the inhibitory "off" surround of the receptive field is being hit by more light, therefore cancelling out the excitatory "on" center

in the center, there is smaller receptive fields, so there is more inhibition

cut in the optic nerve: damage one entire eye of vision depending on which side is cut

cut to optic chiasm: damage to crossover, lose peripheral vision

cut at optic tract: hits r side of brain, lose l of the midline of each eye; if hits l side of brain, lose r of the midline of each eye

cut at optic radiation point: lose top left corner of vision in each eye

cut at visual cortex: can visually see, but can't percieve

organization of LGN

lateral geniculate nucleous

What and Where pathways

patients too!!!!!

monkey with temporal lobe taken out cannot identify an object when commanded to "pick black pen", etc- temporal lobe is responsible for identity (what) - the ventral pathway

monkey with a parietal lobe taken out cannot identify where an object is, so parietal lobe is responsible for location perhaps (where) - the dorsal pathway

EX: the old lady with carbon monoxide poisioning could not line up a card with a slot (damage to the ventral pathway), but could put the card in the slot

the different types of cells correlate to different orientations on the cortex...different neurons can respond to different orientations

example: monkey experiment with lines at different angles firing in different neurons

most neurons prefer to respond to one eye rather than the other (called ocular dominance) and they are organized into ocular dominance columns in the cortex

the cortex consists of a series of columns that alternate in a LRLR pattern of ocular dominance

fovea has more area in the cortex in object representation in the striate/visual cortex

structure: eye (lens compacting)

problem: natural changing of the eye- the ciliary muscles become weaker

effects: can't focus, less accommodation, near point goes farther away

treatment: corrective lens

structure: lens (sun damage)

problem: clouding of lens

effects: difficulty focusing, blindness

treatment: surgery- take out lens, put in synthetic one

Aging of the Iris

structure: iris and pupil

problem: iris swells which prevents controlling of pupil (can't dialate)

effects: problem focusing

treatment: none

structure: retina (detaches from the retinal pigmented epithelium)

problem: visual pigments cant regenerate

effects: loose vision and see floaters in the vitreous humour

treatment: surgery

structure: macula- damage to fovea

problem: decrease in eye pigment which acts as "sunblock" and damage to photoreceptors

effects: problems with central vision, eventual blindness

treatment: prevention eating foods high in lutein and zeaxanthan

structure: cornea

problem: bumpy or irregular cornea

effects: can't focus, blurred vision, distorted vision

treatment: corrective lenses, surgery to reshape cornea

structure: eye's shape is too long

problem: focuses lingt in front of retina b/c of long length

effects: cant see far items

treatment: concave lens

structure: shape of eye is too short

problem: focuses light behind retina b/c shortness

effects: can't see near items

treatment: convex lens

structure: optic nerve/schlemm's canal

problem: build up pressure in eye on optic nerve in vitreous humor from aqueous humor

effects: lose vision from periphery inward leading to blindness

treatment: eye drops decreasing pressure

structure: cornea

problem: injury or scarring of affected structure or vitamin a deficiency

effects: decreased acuity, causes light to appear as a halo, and blindness

treatment: surgery