Lecture 2: Basic elements of neurophysiology and psychophysics 1 Flashcards
Describe Condilac thought experiment
1714-180s
Imagine a statue deprived of all senses
Can statue have any thoughts, any mental life
What did condillac argue
Statue would not have thoughts or mental life
Without any prior sensory experiment statue wouldn’t be able to imagine anything = incapable of having any thoughts
What are our thoughts made up of
Past or present sensory experiences
Where did psychology begin as a scientific discipline
Began with study of perception
What is sensory perception
Process by which we gain consciousness of the external material world and of out bodies = how matter becomes mind
What is fechners law - explain a bit and describe formula
Beginning of psychology as a scientific discipline
P= k X log(S/S0)
What does p stand for
Subjective perception
Function of physical intensity of stimulus
What does S stand for - fechners law
Physical intensity of the stimulus
What does S0 stand for - - fechners law
Smallest physical intensity of the stimulus that can be perceived
Absolute threshold
End point on left of function
Everything will be rescaled according to this
What does k stand for - fechners law
Modality specific factor controlling the steepness of the fucntion
Depends on sensory modality
Mathematically related to webers fraction
Describe fechners law significance
Mathematically connecting objective material phenomenon with subjective perceptions of things
What is fechners law =
Eeuqivalent to newtons law
F=ma
Describe philosophical background - gen
Preoccupied by nature of mind
Burial sites = realized body remained but not person - something is missing, what is it
When Plato
428-348 bc
Describe Plato - explain
Senses gave us shadows of reality - shouldn’t be trusted
Only through reason we can know true forms that structure world
Only thing that matters = immaterial things, souls = immaterial
Senses deceiving us
What is allegory of the cave -Plato
3 prisoners chained to wall - only see shadows
One breaks out (=the philosopher try to get at real objects) and realized Shadows = reflection of objection
Our experience = that of prisoner = things we perceive through our senses are not the real things that exist, just mere shadows
What is Plato’s theory
Theory of forms
What does theory of forms apply to
Beauty
Justice
Describe theory of forms - gen
Real equilateral triangle cannot exit in reality = will always be imperfections, = only idea of it
What matters is the idea of the perfect equilateral triangle
Perfect ideas= forms, exist in separate realm of pure forms that can only be discovered by out reason
Describe theory of forms - relation to us
Concept of perfectly equilateral triangle cannot come from our sensory experience
Souls = fragments of an all knowing cosmos soul, = had all knowledge
We already have knwodleg in us - we have to recover it
Fragments of cosmos soul put into us at birth, lost knowdlege when soul put into body, task as humans = rediscover knowledge
Describe equilateral triangle
Connect Center of 3 equilateral triangle = makes another on e
There to be discovered/rediscovered
Already know everything just need to rediscovery, dismisses sensory infor
When Aristotle
384-322 bc
What was Plato’s view (vs Aristotle)
Problem of realization
Form realized in matter (put into everyday objects we interact with)
What was aristotles view (vs plato)
Form and matter together
Vice versa
What is form - aristotle
Organization of matter
Cannot be form without matter and cannot be matter without form
describe souls - aristotle
We do not have souls that exist independently from body - souls refer to functional organization of living matter
No separate immaterial soul
When Rene Descartes
1596-1650
Define rationalism
Belief that knowledge primarily gained through reason and logical thought
Independent of sensory experience
Define empiricism
Belief that knowledge comes primarily from sensory experiences and observation fo the world
What does Descartes say
Rationalist
Superiority of deductive reasoning over inductive reasoning
Describe inductive reasoning
Drawing general conclusions from specific observations or evidence
Conclusions are probable but not certain (weakness that Descartes sees)
One need one observation to disprove theory
Describe inductive reasoning - ex
Observing that all swans seen so far are white = conclude all swans are white
Not true, when England colonized Australia
Describe deductive reasoning
Drawing specific conclusions from general principles or premises
If premises are true, conclusion must be true
Logical, more certain conclusions
Describe deductive reasoning - ex
All mammals have lungs, whale = mammal so whale must have lungs
Describe inductive reasoning explain more
Start with observation
All humans are mortal
Weakness = one immmortal human proves whole theory wrong
Describe deductive reasoning - explain more
Works on syllogisms
2 premises = major and minor
Major premise = all humans mortal, Descartes is a human = minor premise
Conclusion = Descartes is mortal
True if premises true, have to prove premises true
What are syllogisms
2 premises followed by a. Conclusion
What did Descartes think he could get from deductive reasoning
If a first self evident premise could be identified then all knowledge could be deduced from it
If find one self evident Truth = doesn’t need to be proven = can start chain of deductive reasoning
Need to keep proving premise = infinite regress problem
Describe what Descartes concluded and how
Trying to get self evident truth = engage in preemptive skepticism
Evil spirit deceives him —> thinks what is one thing he cannot deceive him of = I THINK THEREFORE I AM=
NO DENying we are thinking, cannot be fooled into thinking we are thinking bc if we are fooled we are thinking
Certain we having thought = self evident truth
But no way to start any meaningful chain of deductive reasoning from it
What is john Lockes quote
Mind a blank slate (tabula rasa) unto which experience leaves its mark
Everything comes from our senses
Describe lockes theory of ideas
Info from our senses enters our mind as simple ideas (sensations - now called) for instance the simple idea of blue or a triangular shape - these simple ideas can then be assembled (combined) to form complex ideas - for instance the complex idea of blue triangle
Thoughts and knwodlege grounded in sensory info being combine into more and more complex ideas, from outside in
When john Locke
1632-1704
When tichener
1867-1927
Structuralism
Describe what tichener thought
Reverse process = complex thoughts —> simpler (sensory in nature)
Through introspection - tried to go other way around, that is begin with complex or even abstract ideas and decompose them into their simpler elements
Describe what tichener thought - ex
Introspecting on mental imagery associated with concept of meaning
Titchener reported having image of he blue grey tip of a kind of scoop - digging into a dark mass of what appears to be material plastic - weird to us
Similar to synesthesia kinda
When David Hume
1711-1776
What Hume thought - inference
Inference of a nesscary cause and effect (B has to follow A) relationship is invalid, but psychologically we believe their is cause and effect
Cannot know for sure if white ball caused 4 ball yo move= maybe it was weird coincidence (perceiving white ball pushing 4 ball, own action causes 4 ball to go in, but if stick to immediate experience = perceive white ball hitting 4 ball)
Senses do not tell you there is causation- we have tendency to believe causation
What Hume thought- beliefs
Idea of causation = beliefs caused by psychological habits (ex sun rises every morning so far so should expect it rise tmr again)
Causation = psychological habit
What did Kant think
Thought of course there is causation - one of the building blocks of humanity
Used introspection = imagine removing all sensory content from thoughts, there are a certain number of concepts - like causality - that seem to exist independently from sensory experience
Define noumenon
We may never really know thing in itself
What provides sensory info
Define phenomenon
All we can know is impression that the noumenon exerts on our senses
Conclusions Kant
Minds have to contribute innate knwoldge = a priori structures, in order to amke sense of our sensations = SPACE TIME, CAUSE AND EFFECT
Exist in mind before sensory experience
What are a prior structures and describe them
Causation = have causal straucture in mind = allows us to interpret sensory info
Space = do not perceive space, mind organizes it, retina = 2d, info conveyed = 3d so mind extracts 3d from it
Time = exists, we perceive it but cannot feel or see = not by sensory experience, mind produces it by rearranging sensations in temporal order
What can Kant be compared to
Like condilac = if no sensory info nothing happens
Diff - john Locke = but sensory info = meaning less unless have structures to give it sense
Describe William Blake
Can only know how world appears to use
If doors or perception were cleansed everything would appear to man as it is, infinite
1757-1827
Sense and a priori structures provide lens = see world but never be able to know exactly how it is (noumenon)
Describe what philosophers thought about studying the mind scientifically
Like Kant = didn’t think mind could be studied scientifically
1 There is no substance or space in inner observations, only Time = there is nothing to measure, nothing material only time when think = cannot measure objectively
2 Inner observation cannot be separated and recombined at will - cannot play with thoughts
3 Act of introspection changes content of mind
= 3 issue WRONG WITH INTROSPECTION
What did physiologist identify
SEnsory pathways conveying sensory info to Brain and motor pathways controlling msucles
But didn’t understand what happens in between
How brain controls = primary motor cortex —> motor neurons —> spinal cord —> movement
Ex - Perceive temp
When Weber
1795 - 1878
What is Jnd - Weber
Proprioception = position of limbs and forces
Jnd = smallest weight difference someone can Percieve - aka difference threshold
Describe Weber fractions
The just noticeable difference between the standard and comparison weight is always close to 1/40 (or 0.025) of the standard weight - Mathematiucal tool
Ex = standard weight = 40g, comparison = 41 g = 1/40
400g, 410g = 10/400=1/40
= UNTILL THEY NOTICE DIFFERNCE
FROM other types of stimuli fraction differentbut always a fraction
What is discriminability
How easy is it to notice a small differnce in terms of physical intensity
Describe webers fraction and discirminability
High Weber creation = can percieve v small diff
Low fraction = need to have big change between standard and comparison to percieve diff
When fechners
1801-1887
Describe fechners life
Background in medicine and pshyciss and mathematics = studied light
Suffered eye damage from gazing too much at sun while doing experiments, fell into depression
Experienced miracle = vision began to recover, became a very spiritual man and was obsessed with relationship between mind and matter
What is panpsychism
Idea that everything material also has mental aspect
Subjective perception fo external world = mental aspect of that external physical world
Describe panpsychism compared to dualism
DIFFErent - dualism proposes that mind and matter can potentially exist independently from each other
Descartes believes that non human animals did not have souls
By contrast, panpsychism proposed that reality is of one piece but that is has 2 aspects = material and mental
Depends on perspective
Conclusions of fechners
Each Jnd = perceptually equivalent,
Smallest detectable differnce - cannot be further fragmented = called a perceptual atom
Constant fraction fo standard weight
Bring together subjective perception and physical intensity of stimulus
Describe fechners law but graphed
Shows relationship between maters and mental phenomenon
Log shape= grows fast at beginning then slows
Change is subjective - changes in physical intensity the same
All Jnd perceptually euiqvalent
Need larger change to create same subjective change in perception= FOR LARGER VALUES, PROGRESSIVELY SMALLER IMPACT ON SUBJECTIVE PERCEPTion
X= stimulus physical intensity, y = Jnd
Describe role of k value
Diff for every sensory modality
K closely related to Webers fraction
Allows to account for diff slides of log functions for diff senses
Ex = length of lines - weber fraction = 0.001 = v detectable, greatest discriminability
Define discimrinability
Hwo easy it is to discriminate 2 diff intensities
High weber fraction =
Low discriminability
High k value in fechners =
High discriminability
Steeper slope
Webers fraction and k factor =
Almost opposite
Inversely related
What happens when k=1,2,0.5
K = 0.5 = lower, flatter fucntion
K=1 = higher
K=2 steepest, highest
