Week 8-Sensation and Perception 1

Question 1

Explain the different types of sensory energy

Answer 1

Transduction: sense organs convert energy from environmental events into neural activity (electrical signals) (brain does not pervieve objects directly
eye=light stimuli=radiant energy transduced
ear=sound stimuli=mechanical energy transduced
tougue=taste stimuli=recognition of molecular shape
nose=odour=recognition of molecular shape
skin=touch/temp/vibration=mechanical/thermal/mechanical

Question 2

Mullers Doctrine of specific nerve energies:

Answer 2

the sense experienced depends on WHICH nerve is stimulated, not HOW it is stimulated (ex. pressing on eye still makes you see flashes of light even though it is mechanical)
all types of sensory receptor cells are uniquely sensitive to particular types of energy (every sensory domain has “adequate stimulus” ex. light= adequate stimulus for vision)

Question 3

Describe different ways that neurons can code information: place coding, population coding, temporal coding

Answer 3

Place coding: different features are coded by the activity of different neurons in different places (ex. where neurons fire in retina=where object is in space)
Population coding: different features are coded by the pattern of stimulation across a group of neurons
Temporal coding: different features are coded by the rate of firing of a neuron (ex. brightness in light=how fast a group of neurons fire)

Question 4

Describe how physical characteristics correspond to psychological characteristics (ex. loudness, brightness, transduction)

Answer 4

loudness: psychological correlate of a sound intensity (coded in firing rate)
Brightness: psychological correlate of intensity of light which increases as firing rate increases
Transduction=energy to signal to brain
senses travel along cranial nerves

Question 5

Describe sensory adaptation

Answer 5

change in sensitivity that occurs when sensory system is repeatedly stimulated in the same way
occurs when sensory neurons are fatigued (happens after a few seconds of continuous stimulation)
system is less responsive if stimulus is continuously presented (can ignore unimportant stimuli and focus on important stimuli)

Question 6

Compare structuralist, Gestalt, and constructivist (knowledge-based accounts) of perception

Answer 6

Gestalt: whole is not necessarily equal to sum of its parts, can be level of pattern and order at whole that is not accounted for by viewing the parts in isolation (like a illusion)
Structuralist: perception is joining of elementary parts, perception built up from elemental sensations (apple example)
Constructivist: continual adjustment of perception and action to the external output, based on previous knowledge and experience

Question 7

Describe the Gestalt principles contributing to visual perception
Psychology Can Sometimes Cause Gigantic Frustrations

Answer 7

Law of Proximity: elements close to each other belong together
Good Continuation: if there are 2 options, we prefer straight line/smooth continuation/simplest interpretation
Law of Similarity: similar events are a part of the same figure
Law of Closure: elements missing from an outline are filled in by visual system
Law of goo form: we prefer simple, uncluttered objects
Law of Common Fate: elements that move together belong together

Question 8

Compare and contrast sensation and perception

Answer 8

Sensation: psychological process that transforms chemical, mechanical, light and sound energy from world into electrical activity in the brain
Perception: Psychological process involved in organization and interpretation of sensation

Question 9

Explain the psychophysical concepts of just-noticeable difference, absolute threshold, difference threshold

Answer 9

Just-noticeable difference: minimum change required in intensity of something in order to detect that it is now stronger or weaker than it was (ex. light intensity) (ex. taste= 20% JND, so you would have to add/remove 20% of ingredient (say salt) for someone to notice a difference in taste)
Absolute threshold: minimum value of stimulus that can be detected (ex. the highest/lowest pitch noise that someone can hear)
Difference threshold: another name for JND

Question 10

Describe measuring sensations and signal detection theory, nd describe external noice and internal/neural noice in association to SDT

Answer 10

measuring sensations: assumed JND was basic unit of sensory experience and thought each JND was equal to step in psychological magnitude of sensation (ex. juice company makes juice boxes as small as possible so that the JND is just not seen)
signal detection theory: detection of faint stimuli depends on sensitivity and expectation, sensitivity is how sensative your senses are, expectation involves cognitive factors (ex. phone in shower not expecting vs. phone while showering expected to go off)
external noise: plays role if stimulus will be detected (ex. hearing phone if not directly under shower water, or if you poke head out there will be less external noise)
internal noise: plays role if stimulus detected (spontaneous firing rate of neurons, stimulus might not be detected if too weak to raise firing rate of neurons by a lot, but sometimes randomly neurons will fire and you may hear it)