Lecture 2 Flashcards
Fechner’s Law
p= k x log(S/So)
-p= subjective percept
-S= physical intensity of the stimulus
-So= smallest intensity of the stimulus that can be perceived, or absolute threshold
-k= factor controlling the steepness of the function depending on the sensory modality
Antiquity : Plato (Rationalism)
Our senses only gave us mere shadows of reality and should never be trusted. It is only through our reason that we can know the true Forms that structure our world
Antiquity : Theory of Forms
-A real equilateral triangle cannot exist in reality, there will always be imperfections
-What matters is the idea of a perfect equilateral triangle
-These perfect ideas, or forms, exist in a seperate realm of pure forms that can only be discovered by our reason
-Our souls are but fragments of an all-knowing ‘‘cosmos-soul’’ that had all knowledge. Therefor, we already have the knowledge within us, we just need to recover it
Antiquity : Aristotle (Empiricism)
-The form is just the organization of matter. There cannot be form without matter; there cannot be matter without form!
-We don’t have souls that exist independently from our bodies. Our ‘‘souls’’ simply refer to the functional organization of living matter
Rene Descartes
-‘‘I think therefor I am’’
-Superiority of deductive reasoning over inductice reasoning
-If a first, self-evident, premise could be identified, then all knowledge could be deduced from it
Inductive Reasoning
Drawing general conclusions from specific observations or evidence. Conclusions are probable but not certain
-E.g. observing that all swans seen so far are white and concluding that all swans are white
Deductive Reasoning
Drawing specific conclusions from general principles or premises. If the premises are true, the conclusions must be true
-E.g. all mammals have lungs; a whale is a mammal; therefor, a whale has lungs
John Locke
'’The mind is a blank slate (tabula rasa) unto which experience leaves its mark’’
- Information from our senses enters our minds as ‘‘simple ideas’’- for instance the simple idea of ‘‘blue’’ or the simple idea of a ‘‘triangular shape’’. These simple ideas can then be assembled to form ‘‘complex ideas’’ - for instance the complex idea of a ‘‘blue triangle’’
Edward Bradford Titchener
Through introspection, he tried to go the other way around. That is begin with complex, or even abstract ideas and decompose them into their simplier elements
David Hume
-Inference of necessary cause and effect (B has to follow A) relationship is invalid, but psychologically we believe there is cause and effect
-Beliefs are caused by psychological ‘‘habits’’
-E.g. the sun has risen every morning so far, we should expect it to rise tomorrow again
Immanuel Kant
Critique of pure reason
-Didn’t think that the mind could be studied scientifically
Critique of Pure Reason
-‘‘If I imagine removing all sensory content from my thoughts, there are a certain number of concpets - like causality- that seem to exist independantly from sensory experience’’
-We may never know the thing-in-itself (noumenon)
-All we can know is the impression that the noumenon exerts on our senses (phenomenon)
-Our minds have to contribute innate knowledge (a prior structure) in order to make sense of our sensations (space, time, cause and effect)
Just Noticeable Difference (JND)
The smallest weight difference that someone can percieve
Weber Fractions
The JND between the standard and comparison weights is always close to 1/40 (or 0.025) of the standard weight
-For other types of stimuli, the fraction is different, but there is always a fraction
Discriminability
How easy it is to notice a small difference in terms of physical intensity
Gustav Theodor Fechner
-Background in medicine + physical + mathematics
-Suffered severe eye damage from gazing too much at the sun while performing his experiments, he then fell into a deep depression
-Then he experiences what he believed to be a miracle when his vision began to recover. He became a very spiritual man and was obsessed with the relationship between mind and matter
-Panpsychism
Panpsychism
Refers to the idea that everything material also has a mental aspect
-This is different from dualism, which proposes that mind and matter can potentially exist independantly one from another. For instance, Descartes believed that non-human animals didn’t have souls. By constrast, panpsychism proposed that reality is of one piece, but that it has 2 aspects : material + mental
The role of the k variable
K is closely related (but not identical to) to Weber’s fraction. It allows to account for different slopes of logarithmic functions for different sensory dimensions
