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Human sensory perception > Exam 1 (chapters 1-4) > Flashcards

Exam 1 (chapters 1-4) Flashcards

1
Q

What is bottom up processing?

A

Processing based on incoming stimuli from the environment.

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2
Q

What is top down processing?

A

Processing based on the receiver’s previous knowledge (cognitive factors)

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3
Q

Top down processing is also known as

A

Knowledge based processing

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4
Q

Three different ways to approaching the study of perception are:

A
  • Psychophysical approach (Psychophysics) - the stimulus-perception relationship
  • Physiological approach - the stimulus-physiology relationship
  • Physiological approach - the physiology and perception relationship
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5
Q

What is the absolute threshold

A

smallest amount of energy needed to detect a stimulus

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6
Q

Describe the method of limits

A

–Method of limits
•Stimuli of different intensities presented in ascending and descending order
•Observer responds to whether she perceived the stimulus
•Cross-over point is the threshold

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7
Q

What is the difference threshold?

A

smallest difference between two stimuli a person can detect

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8
Q

–Weber’s Law explains this relationship

And uses what formula?

A

DL / S = K

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9
Q

Describe Steven’s Power Law

A 
•P = KSn
–P = perceived magnitude
–K = constant
–S = stimulus intensity
–n = power the stimulus is raised to
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10
Q

Energy is described by

A

Wavelength

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11
Q

Human visual spectrum ranges from…

A

400-700 nanometers

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12
Q

Light can be described as consisting of small packets of energy called

A

Photons

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13
Q

What fixed part of the eye accounts for 80 percent of focusing?

A

The cornea

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14
Q

What part of the eye is responsible for shaping and object distance and makes up 20% of focusing?

A

Lens

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15
Q

Receptor cells in the eye are called

A

Rods and cones

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16
Q

Describe presbyopia

A

•The near point occurs when the lens can no longer adjust for close objects.
•Presbyopia - “old eye”
–Distance of near point increases
–Due to hardening of lens and weakening of ciliary muscles
–Corrective lenses are needed for close activities, such as reading

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17
Q

What is myopia?

A

•Myopia or nearsightedness - Inability to see distant objects clearly
–Image is focused in front of retina
–Caused by
•Refractive myopia - cornea or lens bends too much light
•Axial myopia - eyeball is too long

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18
Q

What is hyperopia?

A

•Hyperopia or farsightedness - inability to see nearby objects clearly
–Focus point is behind the retina.
–Usually caused by an eyeball that is too short
–Constant accommodation for nearby objects can lead to eyestrain and headaches.

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19
Q

Receptors have outer segments which contain:

A

•Receptors have outer segments, which contain:
–Visual pigment molecules, which have two components:
•Opsin - a large protein
•Retinal - a light sensitive molecule
•Visual transduction occurs when the retinal absorbs one photon.
–Retinal changes it shape, called isomerization.

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20
Q

What does a cascade mean?

A

–A cascade means that a single reaction leads to increasing numbers of chemical reactions.

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21
Q

Dark adaption-what happens here?

A
  • Dark adaption is the process of increasing sensitivity in the dark
  • Rod and cone receptors adapt to the dark at different rates and that these differences occur because of differences in their visual pigments.
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22
Q

What are differences between rods and cones?

A 
–Shape
•Rods - large and cylindrical
•Cones - small and tapered
–Distribution on retina
•Fovea consists solely of cones.
•Peripheral retina has both rods and cones.  
•More rods than cones in periphery.
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23
Q

Describe macular degeneration

A 
•Macular degeneration
–Fovea and small surrounding area are destroyed
–Creates a “blind spot” on retina
–Most common in older individuals
•Retinitis pigmentosa
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24
Q

What is retinitis pigmentosa?

A 
•Retinitis pigmentosa
–Genetic disease
–Rods are destroyed first
–Foveal cones can also be attacked
–Severe cases result in complete blindness
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25
Q

About how many rods and cones are in the eye?

A

–Number - about 120 million rods and 6 million cones

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26
Q

What is the “blind spot?”

A

•Blind spot - place where optic nerve leaves the eye
–We don’t see it because:
•one eye covers the blind spot of the other.
•it is located at edge of the visual field.
•the brain “fills in” the spot.

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27
Q

Describe the process of visual pigment regeneration:

A

•Process needed for transduction:
–Retinal molecule changes shape
–Opsin molecule separates
–The retina shows pigment bleaching.
–Retinal and opsin must recombine to respond to light.
–Cone pigment regenerates in six minutes.
–Rod pigment takes over 30 minutes to regenerate.

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28
Q

What does rod spectral sensitivity show?

A

•Rod spectral sensitivity shows:
–more sensitive to short-wavelength light.
–most sensitivity at 500 nm.

29
Q

What does cone spectral sensitivity show?

A

•Cone spectral sensitivity shows:

–most sensitivity at 560 nm.

30
Q

What is the Purjinke shift?

A

Purkinje shift - enhanced sensitivity to short wavelengths during dark adaptation when the shift from cone to rod vision occurs

31
Q

Difference in spectral sensitivity is due to what?

A

•Difference in spectral sensitivity is due to absorption spectra of visual pigments
•Rod pigment absorbs best at 500 nm.
•Cone pigments absorb best at 419nm, 531nm, and 558nm
–Absorption of all cones equals the peak of 560nm in the spectral sensitivity curve
•Fewer short-wavelength receptors, so the curve is determined mainly by the medium- and long-wavelength pigments.

32
Q

What are key components of neurons?

A

–Cell body
–Dendrites
–Axon or nerve fiber

33
Q

What are sensory receptors?

A

•Sensory receptors - specialized neurons that respond to specific kinds of energy

34
Q

Describe recording electrical signals in cell neurons?

A

•Small electrodes are used to record from single neurons.
–Recording electrode is inside the nerve fiber.
–Reference electrode is outside the fiber.
–Difference in charge between them is -70 mV
–This negative charge of the neuron relative to its surroundings is the resting potential.

35
Q

What is the resting potential?

A

–This negative charge of the neuron relative to its surroundings is the resting potential.

36
Q

Describe basic property of action potentials…

A

•Action potentials:
–show propagated response: once triggered, it travels all the way down the axon without decreasing the size
–remain the same size regardless of stimulus intensity
–increase in rate to increase in stimulus intensity.
–have a refractory period of 1 ms - upper firing rate is 500 to 800 impulses per second.
–show spontaneous activity (action potentials occur in the absence of stimuli) that occurs without stimulation – baseline of firing

37
Q

Neurons are surrounded by a solution containing

A

Ions

38
Q

Describe the three ions and their charges

A

–Sodium ions (Na+) - positive charge
–Chlorine ions (Cl-) - negative charge
–Potassium ions (K+) - positive charge

39
Q

When are electrical signals generated?

A

–Electrical signals are generated when such ions cross the membranes of neurons.

40
Q

Membranes have selective permeability (true or false?

A

TRUE

41
Q

What is the synapse?

A

The small space between neurons

42
Q

What are neurotransmitters?

A

–the presynaptic (sending) neuron release neurotransmitters from synaptic vesicles.
–neurotransmitter molecules flow into synapse to small areas on the receiving (postsynaptic) neuron called receptor sites.
–receptor sites are sensitive to specific neurotransmitters: matched like a key to a lock into specific receptor sites.
–used as triggers for voltage change in the postsynaptic neuron.

43
Q

What do excitatory transmitters cause?

A

Depolarization

44
Q

What do inhibitory transmitters cause?

A

Hyperpolarization

45
Q

Rods and cones send signals vertically through

A

–bipolar cells.
–ganglion cells.
–ganglion axons.

46
Q

•Signals are sent horizontally

A

–between receptors by horizontal cells.

–between bipolar and between ganglion cells by amacrine cells.

47
Q

Describe rod sensitivity

A

Convergence Causes the Rods to Be More Sensitive Than the Cones
•Rods are more sensitive to light than cones.
–Rods take less light to respond
–Rods have greater convergence which results in summation of the inputs of many rods into ganglion cells increasing the likelihood of response.
–Trade-off is that rods cannot distinguish detail

48
Q

Describe cell convergence-which has higher convergence, rods or cones? What’s the average of rods to ganglion cells? Etc.

A

•126 million rods and cones converge to 1 million ganglion cells.
•Higher convergence of rods than cones
–Average of 120 rods to one ganglion cell
–Average of six cones to one ganglion cell
–Cones in fovea have one to one relation to ganglion cells

49
Q

Cells that detect features are:

A

•Cells that are feature detectors:
–Simple cortical cell
–Complex cortical cell
–End-stopped cortical cell

50
Q

What is sensory coding?

A

•Sensory code - representation of perceived objects through neural firing

51
Q

What is spatial organisation

A

the way stimuli at specific locations in the environment are represented by activity at specific locations in the nervous system

52
Q

What is a retinotopic map?

A

–Retinotopic map is an electron map of the retina on the cortex

53
Q

What does PET stand for?

A

Positron emission tomography (PET)

54
Q

What does a PET scan do?

A

•Positron emission tomography (PET)
–Person is injected with a harmless radioactive tracer
–Tracer moves through bloodstream
–Monitoring the blood flow: parts of brain that are active will require more “fuel (glucose)” from the blood than other parts.
–Changes in blood flow show changes in brain activity

55
Q

How is the PET activity found in a PET scan?

A

•PET - subtraction method
–Brain activity is determined by:
•Measuring activity in a control state
•Measuring activity in a stimulation state
•Subtracting the control activity from the stimulation activity

56
Q

What happens in a fMRI?

A

•Functional magnetic resonance imaging (fMRI)
–Hemoglobin carries oxygen and contains an iron molecule that is magnetic
–Brain activity takes up oxygen, which makes the hemoglobin more magnetic
–fMRI determines activity of areas of the brain by detecting changes in magnetic response of hemoglobin
•Subtraction technique is used like in PET

57
Q

What does fMRI stand for?

A

Functional magnetic resonance imaging

58
Q

What does the visual cortex show?

A

•Visual cortex shows:
–Location columns
•Receptive fields at the same location on the retina are within a column
–Orientation columns
•Neurons within columns fire maximally to the same orientation of stimuli
•Adjacent columns change preference in an orderly fashion
•1 millimeter across the cortex represents entire range of orientation

59
Q

Describe the “what” and “where” pathways

A

•What pathway also called ventral pathway
•Where pathway also called dorsal pathway
•Both pathways:
–originate in retina and continue through two types of ganglion cells in the LGN
–two pathways serve different functions, but
•they are separated but have some interconnections
•receive feedback from higher brain areas.

60
Q

What are double dissociations?

A

ouble dissociations: two functions involve different mechanisms and operate independently

61
Q

Temporal damage in humans results in

A

–Temporal lobe damage in humans results in prosopagnosia.

62
Q

Which parts of the brain are used for spaces, which part is used for spatial recognition, and which part is used for bodies?

A

•Evidence from humans using fMRI and the subtraction technique show:
–Fusiform face area (FFA) responds best to faces.
–Parahippocampal place area (PPA) responds best to spatial layout.
–Extrastriate body area (EBA) responds best to pictures of full bodies and body parts.

63
Q

The MTL is responsible for

A

Remembering

64
Q

Which MTL structures are important for memory?

A

•Medial Temporal Lobe (MTL) structures are extremely important in memory
–Parahippocampal cortex: surrounds the hippocampus. This region plays an important role in memory encoding and retrieval.
–Entorhinal cortex: functioning as a hub in a widespread network for memory and navigation.
–Hippocampus: plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation

65
Q

Why study perception?

A

•Future careers
–Graduate school work in perception
•Medical applications
–Devices to assist people with vision and hearing losses
•Understanding how you perceive the world
–Color vision
–Depth perception

66
Q

What is the principle of transformation?

A

–When the stimuli and responses created by stimuli are transformed, or changed, between the environmental stimuli and perception.

67
Q

Primary receiving area in neural processing is

A
  • Occipital lobe
  • Temporal lobe
  • Parietal lobe
68
Q

Knowledge is….

A

Any information the receiver brings to a situation

Human sensory perception (1 decks)

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