Week 1- Introduction, Principles and Methods

Question 1

In reality, what are sounds, shapes, colours, smells, heat etc

Answer 1

Physical Stimuli which is tranduced into nerve impulses by our sensory organ.

Question 2

What does perception deal with

Answer 2

The relationship between physical stimuli and their subjective or psyschological correlates.

Question 3

How do we get things into our brains?

Answer 3

Through nerve impulses

Question 4

What does perception determine?

Answer 4

What we believe is real and mediates everything we have ever learned.

Question 5

What are the names for all of our senses?

Answer 5

• Sight, visual eyes
• Hearing- auditory
• Smell- olfactory
• Taste- Gustatory
• Touch- Tactile also haptic- skin

Question 6

What is body awareness sense called?

Answer 6

Proprioception

Question 7

What are the two chemical senses?

Answer 7

Olfaction

Gustation

Question 8

What are the Body Senses?

Answer 8

Somatosenation

Equilibrioception

Question 9

How much of the cortex is involved in visual processing?

Answer 9

50%

Question 10

How is neuropsychology important to perception?

Answer 10

Phantom Limbs, Rubber Hand Illusion, Alien Hand Syndrome, Apperceptive/ Associative Agnosia

Question 11

What is Apperceptive/Asspcoative Agnosia?

Answer 11

Inability to recognise objects

Question 12

How is perception important to clinical psych

Answer 12

Eating Disorders

Inability to recognize facial emotion in psychopaths etc

Question 13

How is perception important to forensic psych

Answer 13

Eyewitness testimony

Question 14

What is the Craik-O’Brien/Cornsweet Illusion?

Answer 14

Which side is lighter with the two squares.

Question 15

What is the first stage of any sensory process?

Answer 15

Transduction

Question 16

What is transduction

Answer 16

Receptors turn energy into neural signals, then impulses travel along axons to terminals which release neurotransmitters across synapses to be received by another cell.

Question 17

What is hierarchical processing

Answer 17

When neural impulses travel ‘up’ the system to the cortex, then relay station in the thalamus (except for olfaction). Higher cortical areas also involve lateral and feedback connections.

Question 18

What is bottom up vs top down processing

Answer 18

Bottom up-
Flow of info from sensory receptors towards ‘higher’ cotical areas with increasing levels of complexity
Top down
-Prior knowledge influences what is perceived
-It is not a dichotomy

Question 19

What is the evidence to suggest that both bottom up and top down exist?

Answer 19

• There MUST be bottom-up, otherwise how would information get in?
• Patients in a coma, or anaesthetised animals show substantial activation through the visual pathway
• Top down influences are clear in the dolphin example, and many, many others
• Forward, lateral and backward connections in the visual pathway demonstrate that information can flow in all directions

Question 20

What are the two physiological principles?

Answer 20

Selectivity, Organisation, Doctrine of Specific Nerve Energies, Plasticity, Noise

Question 21

What is selectivity

Answer 21

Cells are selective for stimuli with certain characteristics (eg. a vertical line)
Response will be smaller the more the stimulus differs from the preferred stimulus
“Tuning” - cell is tuned to 0° (vertical)

Question 22

What is organisation

Answer 22

Within sensory brain regions there’s often an orderly progression of stimulus preferences
Most “important” range of stimulus values is processed by a larger amount of cortex - “Cortical Magnification”

Question 23

What is the doctine of specific nerve energies

Answer 23

Each sense projects to a different cortical area

The nature of a sensation depends on which sensory fibers are stimulated, not on how fibers are stimulated

Question 24

What is plasticity

Answer 24

Neural mechanisms are modifiable
Development
Recovery from brain injury

Question 25

What is noise

Answer 25

Neural firing is stochastic
Precise firing rate determined mostly by stimulus but also by other random factors
Spontaneous Activity - cells fire a little even with no stimulus

Question 26

What are the perceptual principles

Answer 26

Detectability, Sensory Magnitude, Discrimination, Adaptation

Question 27

What is detectability

Answer 27

More intense the stimulus, the more likely you are to be able to detect it!

Question 28

What is the detection threshold

Answer 28

The intensity required for detecting a stimulus
E.g. How light does a circle have to be to be detected against a black background?
Lower threshold is better

Question 29

What is sensitivity?

Answer 29

The opposite of threshold (1/threshold)

Higher sensitivity is better

Question 30

How do you measure detectability?

Answer 30

Method of adjustment -detection- Adjust stimulus until you can just see it

Method of constant stimuli- Yes-No Paradigm- vary intensity
“Can you see it (Yes/No)?”
Plot psychometric function
Curved due to noise
Threshold is 50% point
Problems with criterion differences

Method of constant stimuli- 2AFC Paradigm

• Was the stimulus in interval 1 or 2
• Threshold at 75%.

Question 31

How do you measure sensory magnitude?

Answer 31

More intense stimulus = higher magnitude of sensation

Measure it with a Magnitude Estimation technique.
Present a “modulus” stimulus & call it “10”
Participants rate various stimuli differing in intensity

Compressive non-linear functions .e.g. if you double the intensity, the sensation is less than double

Question 32

What is discrimination threshold or Just Noticeable Difference

Answer 32

The difference between two stimuli required for successful discrimination
Lower is better
Related to precision

e.g.E.g. How different in brightness do 2 circles have to be before we can reliably tell them apart?

Question 33

What is discrimination bias?

Answer 33

What if black rims make the circles look lighter?
If so, we can measure how much lighter they look
How much darker do we have to make them so that they look the same?
Sometimes called the “point of subjective equality” (PSE)
Related to accuracy

Question 34

What is the difference between Precision vs Accuracy

Answer 34

Precision
The degree to which repeated measurements or calculations will show the same or similar results

Accuracy
The degree of conformity of a measured or calculated quantity to its actual (true) value

Question 35

How do you measure discrimination using method of adjustment (matching)

Answer 35

1- Adjust a probe stimulus until it matches the test stimulus
E.g. adjust brightness of a circle until it appears to match one with a black rim. Settings will be slightly different each time (noise)

2-Accuracy represented by the mean of several settings
If mean (average) probe brightness is close to the real brightness of the test stimulus, then there’s good accuracy
If there’s a difference, accuracy is poor: judgements are said to be “biased”

3- Precision represented by the ‘spread’ of settings (e.g. standard deviation)
Low St Dev => high precision => good discrimination ability
High St Dev => low precision => poor discrimination ability

Question 36

What is adaptation

Answer 36

Prolonged stimulation results in a decrease in the rate of firing (physiology)

Question 37

What are the various perceptual consequences

Answer 37

• Increased detection thresholds for same/similar stimuli
• Reduction of perceived intensity for similar suprathreshold stimuli
• Rate at which sensory magnitude rises with stimulus intensity is increased
• Perceived properties of other similar stimuli can appear biased e.g. the motion aftereffect that you saw in the first hour

Question 38

What are the invasive recording techniques

Answer 38

Single Cell Recording

Optical imaging

Question 39

What are the non- invasive recording techniques

Answer 39

Visually evoked potential (vep) and Magnetoencephalography (meg)

-Pet and fMRI