Lecture 3 - Sensation 2

Question 1

What is the Pupil and its function?

Answer 1

The pupil is an opening though which light can enter the eye.

Question 2

What is the Iris and its function?

Answer 2

The coloured part of the eye - controls how much light enters the eye by changing the size of the pupil

Question 3

What is the Cornea and its function?

Answer 3

A clear window at the front of the eye - covers the Iris and pupil. It refracts light back into the pupil.

Question 4

What is the Lens and its function?

Answer 4

The lens, located behind the pupil, focuses light onto the retina at the back of the eye

Question 5

What is the retina and its function?

Answer 5

The retina is a light-sensitive inner lining at the back of the eye - it detects light and converts it into electrical impulses. It contains sensory receptors - rods and cones.

Question 6

What is the Optic Nerve and its function?

Answer 6

The optic nerve carries the electrical impulses created by the retina to the brain’s visual cortex.

Question 7

What is the Fovea and its function?

Answer 7

The fovea is a point of central focus in the eye - allows for high visual acuity, responsible for central vision.

Question 8

What is the Blind Spot?

Answer 8

The point in the retina that has no light sensitive cells - cannot see.

Question 9

How do Cones work?

Answer 9

There are 6 million cones, located in the centre of the retina. Cones have low sensitivity in dim light and are colour sensitive. Cones can’t work well in low light, which is why we become less sensitive to colour.

Question 10

How do Rods work?

Answer 10

There are about 120 million rods, located in the periphery of the retina. Rods have high sensitivity in low light - can function well - but are not colour sensitive.

Question 11

What is the human visual system sensitive to?

Answer 11

Faces - we can rapidly identify information from the fact on a lot of factors (e.g. age, mood..) - facial emotion can be recognised rapidly (angry is recognised fastest)

Question 12

What is Prosopagnosia?

Answer 12

Neurological disorder which leads to inability to recognise faces

Question 13

What are the properties of sound?

Answer 13

Pitch, Loudness/Amplitude, Timbre, and Source

Question 14

What is Pitch?

Answer 14

The frequency of the sound wave that reaches the ear determines the pitch (high frequency = high pitch)

Question 15

What is Loudness?

Answer 15

The amplitude of the sound wave determines the loudness or intensity of the sound (higher amplitude = louder)

Question 16

What is Timbre?

Answer 16

The quality of a sound depends on the mix of frequencies that co-occur (e.g., the difference between the same note on a violin or a clarinet)

Question 17

What is Source?

Answer 17

The location of a sound is determined by differences between auditory information received by each ear

Question 18

How does the Auditory System work? Part 1

Answer 18

Stage 1: Air pressure changes to waves of
fluid in inner ear
• Sound waves directed by pinna into ear
canal
• Waves hit eardrum
• Ossicles (hammer, anvil & stirrup)
amplify pressure waves and transfer
waves to fluid beyond oval window

Question 19

How does the Auditory System work? Part 2

Answer 19

Stage 2: Waves of fluid contact the basilar membrane
• Different frequencies stimulate different parts (thicknesses) of the membrane
• The membrane movement generates further fluid movement to stimulate auditory hair cells that
stimulate nerve cells in the auditory nerve

Stage 3: Neural activity passes from auditory nerve to the auditory cortex in the temporal lobe

Question 20

How does the Basilar Membrane work?

Answer 20

High frequencies displace the basilar membrane in the base of the cochlea, while low frequencies displace it at the tip

Question 21

How do we locate sound?

Answer 21

Based on what ear it reaches first - that ear is closer to the source of the sound.