Sensation and Perception 2

Question 1

What is blind macula?

Answer 1

People fail to perceive stimulus that is directly in front of their eyes
With their attention focused elsewhere, they could be blind to another stimulus in front of them
e.g. gorilla suit clip

Question 2

What is the size illusion?

Answer 2

2 objects are the same size but one of them appears larger
This is because of the depth cues which makes the object appear further away/closer

Question 3

What are binocular cues?

Answer 3

Our two eyes look out onto the world from slightly different positions, meaning each eye has a slightly different view.
This difference between the two eyes’ views is called binocular disparity, and it gives us important information about distance relationships in the world

Question 4

What are hearing thresholds, frequencies and intensities?

Answer 4

Threshold: lowest level of sound that can be heard
Intensity: measured in decibels, loudness
Frequency: measured in Hertz, pitch
Larger Hertz = more waves per second

Question 5

What is a proximal and distal stimulus?

Answer 5

Proximal: stimulus as it appears to the sensory receptors

Distal: actual 3D objects out in the world

Question 6

What is perceptual constancy?

Answer 6

Ability to maintain the same dimensions of an object (e.g. size, colour, shape) even when viewing an object from a different angle or further away

Question 7

What is unconscious inference?

Answer 7

Our perception of size is related to the surrounding objects that can be used as comparison
Also, the amount of space that an object occupies on the retina

e.g. close objects occupy more space on retina than when that same object is far away, but the actual dimensions of the object remain consistent

Question 8

How does light reflect on different surfaces?

Answer 8

White surface: 10% of light absorbed, 90% reflected

Black surface: 90% absorbed, 10% reflected

Question 9

How do we achieve constancy for light and size? How do we use unconscious inference?

Answer 9

For size: estimate the distance using linear perspective or binocular vision, or vergence of our eyes

For light: estimate the location of shadows or estimate the overall brightness of the scene and that that as an estimate of the illusion

We make these adjustments using unconscious inference, there’s no awareness necessary, it’s automatic and is a subconscious process that can ‘reason’ based on available evidence

Question 10

When does the feature detector cell fire?

Answer 10

If an object, falls on a large cluster of neurons that are both excitatory and inhibitory, then the feature detector cell doesn’t fire
This is because there’s an equal balance of negative and positives
If an object only falls on an excitatory neurons, then the feature detector cell fires

Question 11

How is our visual system made up physically?

Answer 11

Left visual field > Right visual cortex
Right visual field > Left visual cortex
Optic nerve crosses at optic chiasm

Question 12

What makes up the outer ear?

Answer 12

Pinna
Auditory Canal
Eardrum

Question 13

What makes up the middle part of the ear?

Answer 13

Malleus: attached to the ear drum
Incus: bound by ligaments to the malleus and to the stapes
Stapes: bound to and strikes against the oval window
Ossicles are the smallest 3 bones in the body

Question 14

What is the middle ear function?

Answer 14

Overload protection is granted by the acoustic reflex which stiffens the ear drum and restricts the ossicles’ movement

Fluid-filled inner ear has more resistance (greater impedance) than the air filled middle ear, sound would be lost if it wasn’t amplified by the middle ear

Amplification is achieved by the ossicles and forces the vibrations from the large eardrum onto the much smaller oval window

Question 15

What makes up the inner ear?

Answer 15

Oval window (part of the cochlea)
Cochlea
Auditory tube
Auditory nerve
Vestibular nerve
Vestibular labyrinth
Semi circular canal

Question 16

What makes up the cochlea?

Answer 16

Nerve
Organ of Corti
Scala Tympany
Tectorial Membrane
Fluid Paths
Round window
Oval window

Question 17

Where is the tectorial membrane?

Answer 17

Organ of Corti sits on the basilar membrane, the part of the organ of corti that makes contact with the basilar membrane is called the tectorial membrane

Question 18

How are the hair cells stimulated?

Answer 18

Tectorial and basilar membranes slide back and forth each other, bending the hair cells

This bend triggers electrical changes in the hair cells
This generates the release of neurotransmitters

Question 19

What are hair cells?

Answer 19

Hair cells are the receptors for hearing
They come in 2 varieties: inner and outer ear
Bending of the hair cells occur in the cilia, not the whole cell

Question 20

What is the temporal theory? What is the issue with this?

Answer 20

Higher frequency = greater number of action potentials in the cochlea
However, each neuron has a refractory period of 1 ms which means we can’t hear frequencies above 1000 Hz
This was modified to the Volley Theory

Question 21

What is the Volley Theory? What is the issue with this?

Answer 21

Group of neurons have inter-leaved responses that could achieve rates greater than 1000 Hz
Depends on one neuron which ‘supervises’ the other inter-leaved responses, this supervisor would have it’s own refractory period of 1ms

Question 22

What is the place theory?

Answer 22

Travelling waves of excitation is maximal at different places on the basilar membrane

Question 23

What is the auditory pathway?

Answer 23

Auditory nerves make there way to the Medial Geniculate Nucleus
Neurons in the MGN project to the primary auditory cortex
Some neurons receive inputs from both ears
These are called binaural neurons

Question 24

What is the mucus layer, olfactory hairs, olfactory filament, olfactory bulb, olfactory tract and limbic system in the olfactory system?

Answer 24

Mucus Layer: the layer of snot, that traps chemicals that are the smell particles

Olfactory hairs: extensions of the receptor cells receive the chemicals

Olfactory filaments: sends message to the olfactory bulb

olfactory bulb: large and collects the signals and relays them to the tract

olfactory tract: gathers the signal and tells the brain there is a smell

limbic system: emotional visceral portion of the brain that interprets the information e.g. i haven’t showered in 3 days

Question 25

What is the tongue, taste bud, papilla, gustatory hairs, gustatory cells and sensory cells in the gustatory system?

Answer 25

Tongue: home for the taste buds, contains 6 muscles

Taste buds: around 10,000 can only see 2/3 of them on your tongue

Papilla: 2 kinds, fungiform and circumvallate

Gustatory hairs: stimulation of these long microvilli send a signal to the larger cells

Gustatory cells: signal from hairs send a wave of depolarization to the sensory nerves

Sensory nerves: cranial nerves (7, 8 and 9) are stimulated

Question 26

What are the 5 kinds of tastes?

Answer 26

Sweet: triggered by sugar e.g. amino acids and saccharine

Sour: triggered by H+ groups (acids)

Salt: triggered by iconic compounds (salts)

Bitter: triggered by alkaloids (OH groups)

Savoury: triggered by aminos (known as umami)