Chapter 4

Question 1

Sensation vs perception

Answer 1

sensation: stimulus (what hits the retina, what your eyes see), a combo of many factors

perception: how your brain interprets what your seeing, the photo your brain decides to display

Question 2

5 Monocular depth cues

Answer 2

monocular=one eye

1. Linear perspective
2. texture gradient
3. interposition
4. relative height
5. relative size

Question 3

Binocular depth cue/ retinal disparity

Answer 3

Retinal Disparity– difference between images each eye sees

-the closer the object, the more different the images on the two retinas

Question 4

Fovea

Answer 4

small depression in the retina where vision is clearest

(ex: foveal vision vs peripheral vision)

Question 5

Photoreceptor cells in the retina

Answer 5

Rods (mostly outside fovea): active under low light conditions

Cones (mostly in fovea): active under normal daylight conditions, detects color and allows us to see fine detail

Retina contain more rods than cones***

Question 6

The closer the object, the more _____ the images on the two retinas

Answer 6

Different

Question 7

Path of retina to brain

Answer 7

1. Light hits retina
   -hits rods (low light) and cones (color)
2. Rods and cones then connect to bipolar cells (middlemen that combine and process signals)
   -rods are compressed, multiple connect to one bipolar cell
   -cones are rarely compresses, usually one cone to one bipolar cell
3. Bipolar cells pass info to Retinal Ganglion Cells (RGCs)
   -filters message even more
   -RGCs’ axons come together and form optic nerve which carries visual info to brain
4. Optic nerve to Lateral Geniculate Nucleus (LGN)
   -sorts info and organizes signals
5. LGN to Area V1 (Primary Visual Cortex) in Occipital Lobe
   -brain’s first visual processing center where you start to interpret shapes colors etc

Question 8

Why must compression happen when retina send info to brain

Answer 8

Way less RCGs (these form optic nerve which carries visual info to brain) than rods or cones, meaning the retina need to compress the info so what’s important is sent to brain

Rods are more likely to be compressed bc there’s so many, cones are more likely to not be compressed and just one cone connects to one RCG as there’s finer detail

Question 9

3 Features of the Primary Visual Cortex (Area V1)

Answer 9

1. its neurons are sensitive to edge orientation (change in light intensity or color, tells ur brain the angle of an edge)
2. Retinotopy/ Retinotopic mapping: patterns of neuronal firing looks like the stimulus
3. cortical magnification: much larger portion of V1 is devoted to the fovea than periphery

Question 10

Feature processing vs binding of features

Answer 10

Picking out features (color shape) is early in visual processing

Combining separate features is done later

Question 11

Dorsal Stream (Where/How Pathway)

Answer 11

One of the two main visual pathways from area V1 (primary visual cortex) Done at same time as ventral**

V1—> V2/V3 —> Middle Temporal (MT) Area —> Parietal Lobe

Main functions: tells your brain WHERE objects are, detects movement, helps you navigate (reach, grab objects)

Question 12

Ventral Stream (What Pathway)

Answer 12

Done at same time as dorsal**

Pathway: occipital to temporal lobe (lower)

Determines object’s shape and identity

Question 13

Visual Form Agnosia

Answer 13

evidence for dual-stream hypothesis (dorsal and ventral pathways happen at the same time)

ex: DF patient has damage to area along ventral stream, can no longer recognize objects, however dorsal stream is not impaired so they can still navigate/perform actions on objects

Question 15

Optic Ataxia

Answer 15

evidence for dual stream hypothesis

damage to parietal regions (dorsal stream) leaves ability to recongize objects intact

Question 16

Properties of sound waves

Answer 16

1. Frequency corresponds to our perception of pitch
   -low frequency=low pitch
2. Amplitude corresponds to our perception of loudness
   -high amplitude=loud sound
3. Complexity corresponds to our perception of timbre*(listener’s experience of sound quality)
   - simples sound wave=pure tone, complex=mis of frequencies, lower quality

Question 17

most sounds are composed with _______ waves at ______ frequencies and _______ amplitudes

Answer 17

most sounds are composed with many waves at different frequencies and different amplitudes

Question 18

How are sound waves converted to waves in the cochlea fluid

Answer 18

1. Sound waves hit the eardrum (tympanic membrane) and cause it to vibrate
2. Vibrations cause movement in the Ossicles
   -A: Hammer (malleus)
   -B: Anvil (incus)
   -C: Stirrup (stapes)
   ABC:HAS
3. Motion of the stirrup (stapes; last tiny bone of Ossicles) pushes against Cochlea and creates waves of cochlea fluid (like stomping on a puddle)
   -inside cochlea: filled with fluid and has basilar membrane running through it with hair cells sitting on it. when stapes pushes fluid in the cochlea, basilar membrane vibrates and and hairs bend, causing vibrations to turn into electrical signals
   -brain uses this to detect sound
4. electrical signals from cochlea are sent to auditory nerve fibers, then (steps later) gets to auditory cortex in temporal lobe

Question 19

Place vs Temporal Coding

Answer 19

Place code: different frequencies stimulate neural signals at specific places along basilar membrane
-high pitched sounds at base of cochlea
-low pitched at tip of cochlea

Temporal code: different frequencies stimulate neural signals at different rates
-low pitched=low frequencies
-limitation: only useful for low frequencies bc nerve cells cannot fire at higher rates

Question 20

Tonotopic organization of primary auditory cortex

Answer 20

specific sound frequencies are received/processed by specific parts of primary auditory cortex:

-low frequency (low pitch) are FRONT of A1
-high frequency processed in BACK of A1

Question 21

Caudal stream (where pathway)

Answer 21

spatial features of sound, allows u to locate source of sound in space

Question 22

Ventral stream (what pathway)

Answer 22

allows u to identify sounds

Question 23

perceptual constancy

Answer 23

person’s ability to recognize objects without being deceived by changing sensory impressions

Question 24

humans perceive the color ___ for the longest wavelength, and ______ for the shortest

Answer 24

longest: red
shortest: violet

Question 25

Figure is to ground as _______ is to _________

Answer 25

Figure is to ground as object is to background

Question 26

modular view

Answer 26

specialized areas of the brain for detecting different stimuli, such as human faces, houses, or even body parts (brain has modules)

Question 27

rule of continuity

Answer 27

helps you perceive individual elements (like lines or chords) as separate rather than immediately grouping them into larger shapes.

Question 28

humans can see wavelengths ranging from

Answer 28

400nm to 700nm

Question 29

sensation vs perception

Answer 29

sensation: simple stimulation of one's sense organs is called perception: interpreting the sensation