Sensation and Perception

Question 1

What is sensation?

Answer 1

Registering stimulation of the senses

Question 2

What is perception?

Answer 2

Processing and interpreting sensory information

This is where consciousness begins

Question 3

What is cognition?

Answer 3

Using perceived information to learn, classify and comprehend

Question 4

Why is studying sensation and perception important?

Answer 4

Racing - need to perceive when to start running
Shooting and aiming
Aid someone’s life by understanding sense
Painting
Tells us about the brain

Question 5

Important concepts

Answer 5

Each external change in the body has a different receptor associated with it, and a different part of the brain

Question 6

What is bottom up processing?

Answer 6

Perception starts with physical characteristics of stimuli and basic sensory processes - features
Don’t need other information to understand what is going on
Direct processing - Gibson - information from sensory receptors is enough for perception to happen. Complex thought isn’t required. the environment contains sufficient cues to provide context to aid perception ie. texture indicates depth

Question 7

What is top down processing?

Answer 7

The perceiver constructs their understanding of external knowledge based on past experience and knowledge
dynamic search for the best interpretation of available data
Despite ambiguous stimuli, you can still make inferences about what is going on eg. hearing lyrics when there are none - filling in gaps

Question 8

What are the methods of investigating sensation and perception?

Answer 8

Staining
Single cell recordings
fMRI scanning
Optical imaging/near infra red spectroscopy
Event related potential from EEG
Computational modelling
Illusions
Psychophysics

Question 9

Lesion studies

Answer 9

Animal - by knife or neurotoxins, ethics - studying faulty system, brain will change
Neuropsychology - damage due to stroke, trauma, boxing etc
Damage can be diffuse, individual variation in damage

Question 10

Virtual lesions

Answer 10

TMS - send pulses of magnetic energy which disrupts activity in the brain for a short period of time (temporary lesion) - used to investigate sensation and perception
eg. TMS on posterior superior temporal sulcus - disrupts biological motion, shows there is a specific part of the brain responsible for motion

Question 11

Psychophysics

Answer 11

Quantifying the relationship between physical stimuli and sensation and perception
Threshold - change from one experience to anther
Absolute threshold - smallest stimuli intensity needed for detection
Differential - smallest difference between stimuli can be detected
Psychophysics has found distrusted biological motion in children with autism

Question 12

How to measure thresholds?

Answer 12

Method of adjustment - change intensity of a stimulus until can no longer detect it

Question 13

Staining

Answer 13

Take dead brain tissue, apply stains, depending on chemical properties, it will stain in different ways (can see structures, layers etc)

Question 14

fMRI

Answer 14

Measure activity that is going on in the brain

Question 15

Optical imaging

Answer 15

Shine light on skulll and sense how much blood is going through

Question 16

Event related potential

Answer 16

Electrodes on head, look at visual stimuli

Question 17

Virtual illusions

Answer 17

No depth cues lead to ambiguity

introspection is a valid way to ask about sensation and perception, consider investigating it systematically

Question 18

Single cell recordings

Answer 18

Put a microelectrode inserted close to cell, action potentials are then recorded
Cortical recordings require section of skull to be removed, only on humans if medical operation (epilepsy)
Identifies selective cells - for certain faces
Evidence - epileptic patients implanted with depth electrodes, presented with photos, text name of people and spoken name. Selective neutrons in medial temporal lobe respond to individuals in multiple sensory modalities