Exam 1

Psychophysical approach

measures the relationship between the stimuli and the behavioral response

what are the 7 steps of the perceptual process

1. distal stimulus (environment)

2. proximal stimulus

3. sensory receptors

4. neural processing

5. perception

6. recognition

7. action

transduction

Transformation of one form of energy into another

top-down processing

Data → features → concept → decision

how does top down processing affect the perceptual process?

using brain to understand what you see

bottom-up processing

Decision → concept → features → data

how does bottom up processing affect the perceptual process

looks at details and puts them together to make sense of things

which approach to measuring perception is asking an observer to tell us the orientation of lines in a grating pattern?

Psychophysical

Physiological approach

measures relationship between physiology and behavior

which approach to measuring perception is measuring how lines of different angles affect brain activity?

stimuli physiological processing (PH1)

which approach to measuring perception is measure a person's brain activity while they are making judgments of line orientation

Physiological Processes Experiences & Action (PH2)

absolute threshold

The point at which you can tell the difference between a stimulus being present and the stimulus being absent

how does the method of constant stimuli help measure the absolute threshold?

helps us understand the minimum level of stimulus required for perception

how does the method of limiting help measure the absolute threshold?

increasing or decreasing the intensity of a stimulus until it's not detectable

who controls the intensity of the stimulus in the method of limiting?

the experimenter

how does the method of adjustment help measure the absolute threshold?

gradually change the intensity of a stimulus until it becomes detectable

who controls the intensity of the stimulus in the method of adjustment?

the individual being tested

what is the difference threshold?

The point at which you can tell the difference between two stimuli

what kind of relationship is the formula for the difference threshold?

linear

what are the 5 additional techniques for measuring perception?

1. magnitude estimation 2. testing recognition 3. reaction time 4. description 5. physical tasks and judgments

which of the 5 additional techniques for measuring perception is this an example of: how much louder is one sound compared to another?

magnitude estimation

which of the 5 additional techniques for measuring perception is this an example of: seeing a duck and saying the word duck?

testing recognition

which of the 5 additional techniques for measuring perception is this an example of: you are driving and you come across a crosswalk the time that it takes from when you see the crosswalk to when you break and stop the car?

reaction time

which of the 5 additional techniques for measuring perception is this an example of interviewing families and parents talking to kids and looking for patterns in a message?

description (specifically phenomenological report)

which of the 5 additional techniques for measuring perception is this an example of: close your eyes and walk to a distant target stimulus in the field (as accurately as possible)?

Physical tasks and judgements

In an action potential how many sodium ions go out of the cell and how many potassium go into the cell?

3 sodium ions out of the cell and 2 potassium ions into the cell

Resting membrane potential is

-70 mV

what is the action potential?

+40 mV

what causes the membrane to become selectively permeable to sodium?

stimulation of the neuron

when does the neuron become selectively permeable to potassium?

when the action potential reaches + 40 mV

what happens when the membrane becomes selectively permeable to sodium?

Na+ flows into the neuron

shift in electrical charge

what happens when a neuron becomes selectively permeable to potassium?

K+ ions flow out of the neuron reestablishes negative charge inside the axon

what kind of NT makes the neuron more likely to fire?

excitatory

what kind of NT decreases the negativity of the inside of the neuron with respect to the outside?

excitatory

depolarization

causes inside of neuron to become more positive

what kind of NT makes the neuron less likely to fire

inhibitory

what kind of NT increases the negativity of the inside of the neuron with respect to the outside?

inhibitory

Hyperpolarization

causes inside of neuron to become more negative

what is neural integration

post synaptic potentials add up

what would happen if EPSPs and IPSPs balance out?

the neuron would remain at rest

How are postsynaptic potentials different from action potentials?

postsynaptic potentials require activation of ligand-gated ion channels

action potentials require activation of voltage-gated ion channel

specificity coding

the idea that an object could be represented by the firing of a specialized neuron that responds only to that object (ex: grandmother cell)

distributed coding

representation of objects by patterns of activity across many regions of the brain

sparse coding

neural coding based on the pattern of activity in small groups of neurons

what is the "easy" problem of the mind body problem?

Understanding how processes work

what is the "hard" problem of the mind body problem?

How do these parts of our brain create consciousness? How are we able to become beings?

what kind of energy is a visual stimulus?

electromagnetic energy

what are the 2 ways to conceptualize light?

wave

stream of photons

function of cornea

gathers and focuses incoming light

outside the eye

function of pupil

allows light to enter the eye

hole in the iris

function of the iris

muscle that constricts or dilates the pupil depending on light levels

colored part of the eye

function of lens

Focuses light onto retina

function of ciliary muslces

controls shape of lens

Function of fovea

point of central focus on the back of the eye (tightly packed with cones )

blind spot

the point at which the optic nerve leaves the eye and no receptor cells are located there

function of retina

where vision actually occurs

only half of light entering eye actually makes it here

made up of photoreceptors

Function of Rods

Helps us see in the dark

black and white 120 million

function of cones

color vision 6 million

distribution of rods

Throughout the retina

helps us see various parts of our visual fields

distribution of cones

In fovea some in periphery

clinical issues involving rods

Retinitis Pigmentosa -bad peripheral view and can't see well in the dark

clinical issues involving cones

Macular Degeneration - Caused by aging blurred vision and can't focus on center of view

wiring of rods

More convergence in fovea which makes it more sensitive to lower light

Wiring of cones

Not sensitive to dim/lower light making it sensitive to detail

dark adaption of rods

Lower threshold Better in low light Takes 25 min to reach min threshold

dark adaptaion in cones

Has a higher threshold takes 5 min to reach Can't see well in dim lighting (can't see colors after it gets dark outside)

How quickly visual pigments regenerate in rods

hours

How quickly visual pigments regenerate in cones

minutes

What is the goal of the eye?

have the image focus on the retina

accomidation

the process by which the eye's lens changes shape to focus near or far objects on the retina

demo

becoming aware of what is in focus

What is myopia?

nearsightedness have trouble seeing objects at a distance

what causes refractive myopia?

cornea too thick

what causes axial myopia?

eyeball is too long same amount of bending but eye ball is longer the eye focuses before getting to the retina

What is hyperopia?

farsightedness (can't see close up)

what causes hyperopia?

not bending light rays enough

What is presbyopia?

decrease in ability to see objects close up

What causes presbyopia?

over time certain lens gets hard and ciliary muscles get weaker

how do visual pigment molecules work to transduce light?

Opsin molecule that light hits then retinal straightens and detaches from opsin (isomerization) to turn light into chemical energy

What is dark adaptation?

process of gradually adjusting to the dark

what causes dark adaptation?

The chemical composition of the rods and cones changes as a result of the lighting changing

What is the dark adaptation curve?

function relating sensitivity to light to time in the dark beginning when the lights are extinguished

what does the dark adaptation curve show?

as adaptation proceeds the participant becomes more sensitive to the light

what does it mean if the curve is downward on the dark adaptation curve?

the participants sensitivity is increasing

what is the role of the rods and cones in the dark adaptation curve

cones help us see until a certain darkness level then rods take over to help us see in super dim light

what is spectral sensitivity?

the eye's sensitivity to light as a function of the light's wavelength

what is the spectral sensitivity curve?

helps us sense color from different wavelengths in rods and cones

neural convergence in the retina

- 120 rods send signals to 1 ganglion cell - 6 cones send signals to 1 ganglion cell

How does neural convergence explain how we have vision in dim light?

More rods converge onto a single neuron which gives us better acuity

what is the pathway through the eye from photoreceptors to retinal ganglion cells?

photoreceptor cell to bipolar cell to ganglion cell

What is a receptive field?

region of a sensory surface that when stimulated causes a change in the firing rate of a neuron that "monitors" that region of the surface

what kind of receptive field are ganglion cells?

center surround

when does lateral inhibition occur?

when light hits both excitatory and inhibitory parts of a receptive field

what determines if the neurons fire during lateral inhibition?

depending on their absolute threshold or they may fire at a slower rate

how can we distinguish between edges and contrasts?

feature detectors help us determine the orientation and complex cells help us determine the orientation and direction

what is the pathway through the Lateral Geniculate Nucleus (LGN) to the visual cortex?

Input: retina, thalamus, cortex, LGN, brain stem
Output: primarily to cortex

what is the superior colliculus's role in programing eye movements?

orients the eye to the object of interest

what is the function of the lateral geniculate nucleus (LGN)?

control flow and organization of information

what role do afferent and efferent nerves play in the LGN?

4 to 1 ratio of afferent to efferent

what do cells respond to in the LGN?

"Lateral inhibition refers to the fact that an excited neuron may reduce the activity of its neighbors. This means that if a single neuron is activated it responds more strongly than if its neighbors are also stimulated since they are often sending inhibition to neurons along the same path"