EXAM 2

Question 1

What is the difference between sensation and perception?

Answer 1

Perception: mental processing of sensory information

Sensation: detection of physical stimuli and the transmission of this information to the brain

Question 2

Be able to differentiate effects on perception that are due to bottom-up vs top-down processes.

Answer 2

Top down processing: perception that is based on previous world knowledge expectations and past experiences.

EX: put together that the horizontal lines look like a B

Bottom up processing: perception that is based on the physical properties of the stimulus

EX: light hits cells in the retina, affecting their firing rate

Question 3

What does it mean to say that every receptor has an adequate stimulus?

Answer 3

Every sensory receptor has a particular type of stimulus energy to which it is most sensitive

I.e photons for photoreceptors, hair cells mechanically being pushed for hearing

Question 4

What is the adequate stimulus for photoreceptors (e.g., vs hair cells)?

Answer 4

Photons

Question 5

Be able to differentiate between a distal stimulus and a proximal stimulus.

Answer 5

Distal stimulus: an object or event out in the world

Proximal stimulus: energies related to the stimulus that we came in contact with

Question 6

Be able to trace the complete pathway of visual information, from a distal stimulus to V1 (and from 10 class, out to FFA/PPA).

Answer 6

Distal stimulus → back of retina (if up, then lower retinal cells, if down then upper retinal cells—rod/cones, horizontal cell, bipolar cell, amacrine cell, ganglion cell) → optic nerve

Fovea: point of central focus

Photoreceptors (rods and cones) absorb photons of light

Stacks of pigment in the outer segment of rods contain opsin which changes the shape when hit by a photon of light

Left visual field → light side of retina → optic chiasm → Lateral geniculate nucleus → V1 (primary visual cortex)

Question 7

What is the fovea?

Answer 7

Point of central focus

Question 8

What are the differences between rods & cones?

Answer 8

Rods:
- Not color sensitive
- Respond to low intensity light (good at night)
- Distributed throughout the retina (NOT IN THE CENTER)

Cones:
- Color sensitive
- Requires higher intensities to respond
- Concentrated near the center of retina (FOVEA)

Question 9

What do the layers in the lateral geniculate nucleus indicate?

Answer 9

Layers 2,3,5 – info from ipsilateral eye (same side)

Layers 1,4,6 – info from the contralateral eye (opposite side)

Question 10

Understand the idea of a retinotopic map

Answer 10

• Neural activity in the retina and brain organizes information about locations of objects and parts in visual space.
• Retinotopic map: a map in which each point in brain tissue corresponds to a location in the retina

Question 11

Be able to explain how visual perception of edges could be enhanced through lateral neural connections (“lateral inhibition”)

Answer 11

• Moch bands
• Enhanced edges is BOTTOM-UP processing (can only enhance what is already there
• When the high intensity and low intensity lights hit, the interconnected cells receive different intensities – that results in lateral inhibition as bipolar cells respond differently at the edges with 2 different shades right next to one another

Question 12

Recognize / identify examples of visual perceptual grouping principles.

Answer 12

Perceptual grouping: sensory information is grouped into organized wholes

Gestalts: forms/shapes

Gestalt Principles:
a. Proximity: group close items together
b. Similarity: group similar items together
c. Continuity: group edges/contours together that have the same orientation
d. Closure: complete figures that have gaps
e. Illusory contours: perceive contours and cues to depth even when they do not exist
f. Object constancy: maintenance of constancy across various perceptual contexts (lighting, size, shape, ect.)
i. Tea cup in different orientations can still be identified as a stimulus

Transduction: changing the format of the stimulus to a neural signal

Question 13

Be familiar with the different types of retinal cells and what they are “optimized” for with regard to the range of intensities and wavelengths of light. How does this cell specialization result in color vision? (What is the trichromatic theory of color vision?)

Answer 13

Wavelength: the distance between 2 corresponding points on a wave
Frequency: the number of waves that pass a point in space during any time interval, usually one second

Cones detect color; there are 3 different types of cones, small, medium, and large that corresponds to the wavelengths that they are stimulated by (small wavelengths, medium wavelengths, and large wavelengths)

Small = Blue
Medium = Green
Large = Red

Question 14

Be able to identify the color that would be perceived given different wavelengths of light. (What color would you perceive if presented with “red”, “green”, and “blue” wavelengths simultaneously?)

Answer 14

All 3 colors simultaneously would be perceived as white where all the cones are perceived as white

Purple does not exist: mix of red and blue light

See different colors depending on the neural response which can be mixed depending on other cone cells stimulated

Question 15

Be able to explain two different ways of perceiving a color such as yellow, given that there are no cones that respond to “yellow” wavelength.

Answer 15

One way is that you could have it is red and green light simultaneously mixed results in yellow

You see light that is about 550 nanometers and both your red and green cone cells fire to create yellow

Question 16

What are some ways that mutations can affect color vision?

Answer 16

a. Color Blindness is commonly due to inherited deficiencies in the cones. Most of the genes are on the X chromosome so males are more often affected.

b. Can acquire via degenerative disease (age, macular degeneration, diabetes) or brain or retinal damage (exposure to UV light)

c. If you miss the cones for certain wavelengths then you cannot distinguish between long wavelengths; i.e cannot get long wavelengths, then you cannot tell between yellow, orange, red or green. (Protanopia)

d. If some cone cells overlap with one another (green recognizes the same wavelengths as red and less of its own): you would not be able to as easily see greens or distinguish it from red. Deuteranomaly

Question 17

Explain what “color constancy” is and be able to recognize/give examples.

Answer 17

Color constancy: perceived color of objects remains constant under different illumination

EX: Snow on camera looks blue, but our brain corrects it to look white

EX: dress color where our brain corrects the blues into whites

Question 18

Explain what “object constancy” is and be able to recognize/give a new example

Answer 18

Object constancy: maintenance of constancy across various perceptual contexts (lighting, size, shape, ect.)
I. Tea cup in different orientations can still be identified as a stimulus
NOT things hidden by things

Question 19

Where is the FFA+ PPA located? (lobe? hemisphere?)

Answer 19

FFA: Inferior temporal cortex (both hemispheres) in the fusiform gyrus on the RIGHT side specifically
PPA: parahippocampal gyrus in BOTH hemispheres in the temporal lobe

Question 20

What is binocular rivalry?

Answer 20

Binocular rivalry: the phenomenon in which conscious perception alternates between images shown separately to each eye, rather than the perception of a “mixed” image

EX: house and face on top of one another

Question 21

What exactly does the FFA seem to do that other areas (OFA) and pSTS do not do?

Answer 21

Focuses specifically on faces and integrates both face parts and their configuration

Question 22

What is the extrastriate cortex?

Answer 22

A region of the occipital lobe outside of V1

Question 23

Understand the details of the research design in the Tong et al paper and be able to relate the particulars of the experiment to the research question.
What was the research question?

Answer 23

When/where along the visual pathway binocular rivalry is resolved? Is it before or after the extrastriate cortex?

Question 24

Understand the details of the research design in the Tong et al paper and be able to relate the particulars of the experiment to the research question.
Why did they present faces and houses (rather than apples and oranges)?

Answer 24

Face processing and place/object processing are different so it created binocular rivalry

Question 25

Understand the details of the research design in the Tong et al paper and be able to relate the particulars of the experiment to the research question.

Under what conditions does someone experience binocular rivalry?

Answer 25

Someone can experience binocular rivalry in which each eye is shown something separate rather than the perception of a mixed image AND different regions of the brain

Question 26

Understand the details of the research design in the Tong et al paper and be able to relate the particulars of the experiment to the research question.
What was the point of the non-rivalry condition?

Answer 26

To act as a control

Question 27

Understand the details of the research design in the Tong et al paper and be able to relate the particulars of the experiment to the research question.

What was the evidence from the study that convinced the researchers that binocular rivalry is resolved before extrastriate cortex?

Answer 27

The study used fMRI to study whether activity in the extrastriate cortex is correlated to visual awareness during binocular rivalry and whether activity changes during rivalry might be comparable to those found during nonrivalrous stimulus alternation

IF RESPONSES EQUIVALENT then resolved before it hits the extrastriate cortex

Graphs below prove that is true

Question 28

What is a double dissociation? What is the evidence for a double dissociation between object recognition and face recognition?

Answer 28

Double dissociation: A but not B AND B but not A so they are entirely independent

OFA conduits an early stage of face processing (face parts)

pSTS may be involved in the discrimination of gaze direction and expression

FFA carries out an integrated, holistic representation that contains both kinds of information (face parts and their configuration)

Prosopagnosia is the difficulty recognizing a face BUT can recognize objects so single dissociation

Object agnosia is the difficulty recognizing objects BUT can recognize faces so it is a double dissociation

Question 29

What characteristics of a sound wave correspond to pitch and volume?

Answer 29

Sounds: Pressure changes as vibrations push on air and molecules get squished together resulting in waves and creates a repetition pattern of alternative high and low pressure regions

Amplitude: difference in pressure between peaks (low and high) → CORRESPONDS TO VOLUME/LOUDNESS

Frequency: number of times the wavelength occurs in one second (kHz) → CORRESPONDS TO PITCH

Question 30

Compare and contrast the retina as it pertains to vision and the cochlea as it pertains to hearing.

Answer 30

The retina is stimulated by photons, the cochlea is stimulated by pressure changes

The retina maps directly onto the world, while the ear doesn’t have a direct map, rather is based on other metrics to identify a stimulus

SIMILAR: retina has 3 types of cone cells for short, medium and long wavelengths, and the cochlea has 3 types of hair cells for low, medium and high frequencies

Question 31

What is the auditory pathway?

Answer 31

AUDITORY PATHWAY:
1. Sound waves enter the auditory canal of the outer ear

2. Vibrations hit the eardrum
3. The eardrum vibrates, passing on those vibrations to the middle ear
4. Bones in the middle ear transfer vibrations transfer the vibrations to the inner ear

5a. Vibrations in the liquid in the cochlea jiggles basilar membrane

5b. The hair cells are bent as a result against the tectorial membrane because the basilar membrane pushes them up which releases an action potential (stereocilia: protein filaments that brush up against the tectorial membrane)

A. Being of stereociia causes a MECHANICAL opening of the hair cell

B. Positively charged potassium ions enter and depolarize the cell

C. This opens voltage gated channels to open, allowing calcium ions to enter the cell

D. triggers the release of neurotransmitters at the bottom of the cell

5c. Tonopoy: neural response to different frequencies lines up spatially on the basilar membrane

6, 7, 8. Info is sent to the brain stem, the midbrain, and the primary auditory cortex

Question 32

Be able to point to A1 vs V1 on a brain or brain scan.

Answer 32

Question 33

What leads to the firing of a hair cell? How does this differ from photoreceptors?

Answer 33

A mechanical stimulus: hair cells are bent

Photoreceptors are hit by photons

Question 34

Be able to label and identify the role of the following: ear drum, cochlea, organ of corti, stereocilia, medial geniculate nucleus (in the thalamus), and primary auditory cortex (A1).

Answer 34

Ear drum: vibrates due to pressure changes and passes those on to the middle ear

Cochlea: Where the vibrations are turned into neural signals with hair cells. Base of cochlea corresponds to the highest frequencies (20000 Hz) while the apex corresponds to shortest frequencies (20)

Organ of corti: within the Cochlea, includes the basilar membrane, the hair cells, the tectorial membrane and the axons of sensory neurons that go to the auditory nerve

Stereocilia: the hair cells

Medial geniculate nucleus:
Acts as the principal relay nucleus for the auditory system between the inferior colliculus and auditory cortex.

Primary auditory cortex:
Aggregates and processes the sounds that you hear

Question 35

Generally speaking (ventral vs dorsal areas), where is information about “what” an visual object or auditory sound is vs “where” a visual object or auditory sound is?

Answer 35

What a visual object/auditory abject: identifying sounds and ventral steam – starts in the temporal lobe and goes to the frontal cortex
Where a visual object/auditory object: localizing sounds, dorsal stream

Question 36

Describe/apply two ways that we localize where a sound is coming from. (For example, know which ear would be in the “acoustic shadow” or would be the first to receive the sound wave.)

Answer 36

Interaural time difference: there is a time-delay between the two ears, depending on the location of the sound source

Interaural level difference: the head gets in the way of high frequency sound waves, creating an acoustic shadow between the 2 ears (one ear receives info first)

Question 37

Be able to recognize or give examples of how auditory grouping can help us to separate the cacophony of simultaneous sounds around us into separate percepts. How do these principles also lead us to have auditory “illusions”? (Relatedly, think about how grouping principles in vision could lead to visual illusions?) Be able to explain the principles that give rise to each of: auditory stream segmentation, continuity illusion, and Shepard tone

Answer 37

Auditory scene analysis:
Separating stimuli into separate percepts

Auditory grouping principles:

Onset time

Location

Pitch (combo of pitches)
Perception of a group in accordance with proximity of pitches (successively rising and falling)

Timbre (quality of sound that allows you to identify a guitar vs a flute)

Illusions:

Auditory stream augmentation:
Rapid alternation of high-low sounds create the illusion of 2 sound sources due to perceptual grouping

Continuity illusion:
Perceive sounds as continuous if the gapes are “filled with something else that can be interpreted as the reason for the gap.

Shepard tones:
Playing of 1 or more sequential tones (each separated by an octave)
Sounds like it is constantly going up

Cocktail party effect:
The phenomenon of filtering out a range of stimuli (visual, auditory, touch) when focusing auditory attention on a particular stimulus

Question 38

Explain how the dichotomous listening tasks and the monkey business illusion demonstrate top-down effects of attention allocation on perception? (“How” meaning, what specifically about participants performance on these tasks demonstrates the role of attention allocation. If attention allocation did not affect perception, how would participants’ performance have been different?)

Answer 38

Dichotic listening task: 2 different auditory stimuli are presented simultaneously

• When you focus on one, you cannot know the other

Attention allocation determines what you actually process and what you filter out