Lecture 4 Flashcards
what was Stanley Smith Stevens’ question
1906 - 1973
In proportion, how much more/less intense are two stimuli of different intensites perceived?
(with regard to fechner)
what did stevens test
he wanted to test magnitudes
so fechner’s y axis was very broad/arbituary and stevens wanted to know actual numbers of stimuli
what is the name of the equation stevens came up with
Stevens’ power law:
what is Stevens’ power law:
R = aSb
explain each of the parts inn R = aSb
R: Response
S: Stimulus magnitude
b: controls the curvature of the function
a: corrects for the scaling of measurement units used for S
what is another variation of stevens power law
R = aψ ψ=Sb
what is ψ:
Perceived intensity
what was the problem with Stevens expierments
the modules
why do you choose the intensity and why do you tell participants it is that number of intensity?
how did this issue that steven had become eliminated
absolute magnitude ratings
what re absolute magnitude ratings
Absolute magnitude ratings: How intense is a percept in relation with two «absolute» boundaries?
0= no pain 100 = worst pain imaginable
what is an issue the absolute magnitude ratings
it is difficult to imagine extreme pain
what is the problem and solution to absolute magnitude ratings
Problem: is my «10/100» equal to your «10/100»
Solution: cross-modality matching
what is cross-modality matching
use another sensory modality to rate a sensory perception
for example, match sweetness of coke to auditory sound
‘super sweet tasters’ right rate a coke slower in sweetness than normal people so then this was identified and they could do further research
what are the nervous systems
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Nerves in the body
what is included in Central Nervous System (CNS)
brain + spinal cord
what is included in Peripheral Nervous System (PNS)
Nerves in the body
what are the The Four steps of sensation and perception
Physical stimulus
1. transduction –> 2. transmission –> 3. perception
what is transduction
The physical stimulus interacts with a specific receptor located on a peripheral sensory neuron and causes the neuron to fire, i.e. the stimulus is transduced into a electrical signal
what is the Doctrine of specific nerve energies
A doctrine formulated by Johannes Müller (1801–1858) stating that the nature of a sensation depends on which sensory fibers are stimulated, not on how the fibers are stimulated.
give an example of how the nature of a sensation depends on which sensory fibers are stimulated, not on how the fibers are stimulated.
when you eat something minty (methane) it feels cold but it actually not the sensory fibres for cold are just stimulated which makes you think it is cold
same with heating a hot pepper
who came up with the Doctrine of specific nerve energies
Johannes Müller
what is important to understand about action potentions
they are an all or non phenomenon
what are the different types of actions potentials
no stimulus, weak stimulus, strong stimulus
what happens to the neurones in no stimulus
there is a baseline firing that happens in our nervous system, so it fires occasionally but nothing out of the ordinary
what is the Second step in physical stimulus -
transmission
what is transmission
The signal is transmitted to the brain
what is the only stimulus to have sensors in the spinal cord
pain
all others transmit directly to their respective locations
what are the types of nerves that go to the brain
sensory and motor
what nerves do we have to focus on in this class
sensory
what are the sensory nerves
optic (vision)
olfactory (smell)
trigeminal (face, touch and pain sensation in face)
Facial (tongue, soft palette)
Vestulochoclear (spatial orientation, balance, hearing)
glossopharyngeal (posterior tongue, tonsils, pharynx, pharyngeal muscles)
vagus (internal organs and orgasms; heart, lungs, gastrointestinal tract, bronchi, trachea, larynx)
what is the third step in sensation and perception–perception
The signal reaches the cortex and produces a counscious perceptual experience.
what is the fourth step in sensation and perception
modulation
what is included in modulation
Cognitive factors, like expectations, attention, etc. will influence how sensations are perceived.
e. g. Top-down vs bottom-up processing
e. g. Bayesian prediction process
give an example of a bottom up process
you see a light and then the nerves fire and go to your brain and you perceive a light
give an example of a bottom down process
you take a placebo, you think it is real and it impacts your brain to believe something is happening
what is the Bayesian prediction process equation
P(A | B) = P(B | A) P(A) / P(B)
explain the parts to the Bayesian prediction process equation
P(A|B) = Probability of A (e.g. having cancer) given B (e.g. test is positive)
P(B | A) = Probability of B (e.g. test is positive) given A ( e.g. having cancer)
P(A) = Probability of A (e.g. having cancer)
P(B) = Probability of B (e.g. test is positive)
