thinking lectures 1 and 2 recap notes on bayes when studying this! Flashcards
what is thinking?
process in the mind
organisation and manipulation of internal representations
which debate shows how different representations are formed?
rationalism vs empiricism
what is rationalism?
reason is enough for knowledge
what is empiricism?
knowledge should be created through obeservation and experience
importance of sensory observations
what do algorithms suggest about thinking?
perception doesnt directly map the physical world to the mind
instead it is an inference process, and the brain uses algorithms to construct an image of the world
how does the brain use integration for thinking?
integrates specific observations with different contextual information
what can interpretations depend on?
what we are primed with
what are the two opposing ideas for how human cognition works?
human cognition is based on Bayesian algorithms
OR
humans fail to take prior probabilities/base rate into account
what is Bayes formula for inference?
p(H1|O)= (p(H1)xp(O|H1))/p(O)
what does p(O|H1) mean?
probability of a certain observation O given that hypothesis B1 was true
(true positive)
what does p(H1) mean?
prior probability of hypothesis H1 being true
what does p(O) mean?
prior probability of making observation O
(positive)
what does P(H1|O) mean?
posterior probability of H1 being true given observation O being made
what do we use Bayes’ theorem for?
the likelihood of perceptions occuring
how can Bayes’ theorem be used for senses?
can derive how senses are combined to result in a common judgement
what happened when Ernst and Banks (2002) investigated perception?
VR task
compared the heights of two bars
can measure the accuracy of judgement in the visual and somatosensory domain
in combined perceptions, judge how much their judgement depends on visual vs haptic perception
what does the psychometric function do?
relates an observer’s performance to an independent variable
how do psychologists use the psychometric function to assess perceptions?
ppts had to judge whether a second stimulus was larger than the first
different ppts have different sensitivities to the difference
psychometric function often modelled as a cumulative function/S shape
better performance=steeper curve
how did Ernst and Banks (2002) investigate the psychometric function?
had a standard and comparison stimulus
measured the psychometric function- haptic stimulation only/visual stimulation/at different noise levels
get different psychometric functions for the different conditions
what sense is haptics?
touch
did Bayes theorem predict how visual and haptic stimuli were used?
yes, predicted how they were used for optimum perception
people benefit from combining information
what did Stocker and Simoncelli (2006) investigate?
looked at noise characteristics and prior expectations in human visual speed perception
how did Stocker and Simoncelli investigate visual speed perception?
presented moving gabor patches/gratings at different speeds or contrast levels
what hypotheses did Stocker and Simoncelli have when investigating visual speed perception?
low contrast stimuli will be perceived as more ambiguous
ppts will be biased to perceive motions as slower than they are
perceived motion of low contrast gratings will be slower than high contrast gratings
what hypotheses did Stocker and Simoncelli have when investigating visual speed perception?- were these hypotheses confirmed
yes
the Bayesian observer model explained the behavioural data for different motions speeds and contrasts well and better than other models
what is a criticism of Ernst and Banks’ study?
didn’t investigate whether participants integrate sensory signals and prior probabilities
what is a criticism of Stocker and Simoncelli’s study?
didn’t manipulate the prior probabilities- only estimated them
