Background Knowledge

Question 1

Which primary (and secondary) brain vesicle does the cerebral cortex come from?

Answer 1

Forebrain (Telencephalon)

Question 2

Which primary (and secondary) brain vesicle do the thalamus and hypothalamus come from?

Answer 2

Forebrain (Diencephalon)

Question 3

Which primary (and secondary) brain vesicle do the cerebellum and pons come from?

Answer 3

Hindbrain (Metencephalon)

Question 4

Which primary (and secondary) brain vesicle does the medulla come from?

Answer 4

Hindbrain (Myelencephalon)

Question 5

What is the Neuron Doctrine?

Answer 5

The concept that the nervous system is made up of discrete individual cells, a discovery due to decisive neuro-anatomical work of Santiago Ramón y Cajal in the early 1900’s

Question 6

Who was Hermann von Helmholtz? And with respect to psychophysics, for what is he well-known?

Answer 6

Helmholtz was a German physician and physicist who was interested in the relationships between measurable physical stimuli and their correspondent human perceptions. He sought to demonstrate that nerves conduct signals at finite velocity using crude velocity techniques (results were variable and inaccurate). He did find that the signal velocity was 10’s of milliseconds

Question 7

What is the nature of neural processing?

Answer 7

Comprises of the neural code which utilises action potentials (spikes).
Individual AP’s do not differ from one another.
Code is based on space (Which neurons are firing) and time (precise time sequence of a series of spikes or “the spike train”)

Question 8

How does the action potential convey the strength of the signal?

Answer 8

By its frequency

Question 9

How many neurons are there in the human cerebral cortex?

Answer 9

17 billion

Question 10

How many neurons are there in the human cerebellum?

Answer 10

69 billion

Question 11

How many synapses are there in the human brain?

Answer 11

10^14

Question 12

What is the rate code?

Answer 12

The average spike frequency

Number of spikes over some time/ the interval between events

Question 13

What is the temporal code?

Answer 13

Precise timing of the spikes within a spike train

Question 14

How fast do action potentials travel along nerves?

Answer 14

<1m/s to >100m/s. Majority <10m/s

Question 15

How quickly can APs be generated?

Answer 15

Varies with cell type and species

Fastest= 2ms (spike + absolute refractory period)

Question 16

What is the maximum firing rate?

Answer 16

500 spikes per second

Question 17

Define sensation

Answer 17

Reception of sensory data

Awareness of a physical stimulus through the senses

Question 18

Define perception

Answer 18

Recognition, integration and interpretation of raw sensory information/ stimuli

Question 19

What are the two theories of perception?

Answer 19

Direct perception (naive realism)
The representational model of the mind where there is the outer world, with its mass, and physics and molecules and the inner world (where we make sense of abstract concepts)

Question 20

What evidence is there for radical skepticism i.e. Can we entirely trust our senses?

Answer 20

Illusions: misinterpreted perception of a sensory experience
Hallucinations: perception in the absence of a stimulus

Question 21

What is the “hard problem”?

Answer 21

Proposed by Chalmers (1995), the hard problem refers to the fact that mental events (e.g. sensations) seem qualitatively different from the physical

Question 22

Define dualism

Answer 22

The mind and body are separate substances

Question 23

Define materialism (physicalism)

Answer 23

The mind is the brain or arises from the physical activity of the brain

Question 24

Define functionalism

Answer 24

The mind is what the brain does: the brain is hardware and the mind is software

Question 25

What is Shepard (1990)’s experiment?

Answer 25

Drawing of two tables where one is horizontally and vertically oriented. One seems longer than the other when in fact they are the same size.

This is perception by inference- the hypothesis is constrained by existing knowledge as well as the current sensory neural data

Question 26

Who proposed the term “perception as unconscious inference”?

Answer 26

Helmholtz (1867)

Question 27

What is the Bottom-Up theory (feed forward)?

Answer 27

• Physical characteristics result in a particular perception
• Perception is driven by physical characteristics of the stimuli
• Suggests a realist view of the world
  o A square is a square because it presents itself with four sides of equal length set at right angles to one another. We match features with stored knowledge
• Gibson (1966): In visual perception, patterns of light received by the retina are all that is necessary for perception to occur.
• Well-designed objects suggest their use (affordance)
• Texture gradients- converging lines give the appearance of depth. Closely packed together things suggest objects are further away. Objects are not as large as they seem to appear
• Perceiving Motion- closer objects seem to move more quickly.
• Horizon ratios- used to judge the vertical height of an object

Question 28

What is the Top Down theory (feedback)?

Answer 28

• Involves the combination of sensorial data with other psychological constructs e.g. expectations, previous experiences or other sensory information to provide context
• Hoover and Beezil proved that that visual input from birth is required to develop the visual cortex
• Perceptual Grouping- we perceive objects as “going together”. This makes the world simpler
• Effect of past experience- You can’t “unsee” something, regardless if you remember having seen it
• Expectation Effect- a bin may seemingly be a burglar if you take the garbage out in the middle of the night

Question 29

What are pitfalls of the Bottom Up Theory?

Answer 29

Retina is a curved 2D surface yet we perceive the world as 3D. Two eyes yet we perceive one visual world- integration process.

Impenetrability- we know that perception is occurring but we can’t switch it off