Lecture 2 - A Brief History of Cognitive Psychology Flashcards
computational complexity
you have too many choices to process at any given one time
The brain cannot deal with this - there are too many stimuli and choices to process at each moment in time.
Your attention system(s) help
bias/constrain what you process at any one time.
Eye attention system
eyes are constantly in motion, saccading about
every 300 ms. They are drawn to items that are
visually salient – high contrast, novel, or
different than the surroundings.
− This is considered a bottom-up, automatic process.
• We also have background knowledge that
informs our visual search.
− This is considered a top-down, deliberate process.
How does a mind/brain survive (and thrive) in
a complex world that is constantly changing?
• There are too many events and changes in
your immediate environment to constantly
monitor and consider everything.
• The brain cannot deal with this computational
complexity – there are too many stimuli and
choices to process at each moment in time.
• We need internal (innate or learned) biases or
constraints that work with external cues to tell
us what is immediately relevant.
how do we tell what is immediately relevant?
crossing the street
We need internal (innate or learned) biases or
constraints that work with external cues to tell
us
gavagai problem
How do you learn what is relevant in a particular situation?
Suppose something runs by and the person next to you points and says “gavagai.” What does the word refer to? − Rabbit? − Fur? − Running? − Food? − Undetached rabbit parts?
This is W. V. O. Quinne’s problem of
indeterminacy of translation.
gavagai problem
at any particular stimulation the stimuli will under-specify some unique meaning
you need innate help to identify a particular meaning with a word (gavagai)
we need some constraints on learning
natural biases or expectations
what does that help determine?
Organisms seem to have natural biases or expectations about stimuli in their environments. This help them determine what is specifically relevant to them.
Ellen Markman (1989)
found that young children have a bias for
assuming that labels refer to whole objects, rather than parts of objects.
− This is known as the whole-object constraint.
• Markman also found that labels can be extended to other objects of the same kind.
− This is the taxonomic assumption.
• Both biases appear to be innate and help constrain how words are learned and applied to objects (gavagai –> whole rabbit).
whole object constraint
innate, specific to humans
children have a bias for
assuming that labels refer to whole objects, rather than parts of objects.
taxonomic assumption.
labels can be extended to other objects
of the same kind.
(other types of rabbits or gavagai or dogs, etc…)
Some biases in learning may be species specific
• Rats appear to easily associate tastes
and smells with illness due to food.
• Pigeons are more likely to associate
visual cues with food.
• Each innate bias fits the evolutionary
niche of the animal and is generally
adaptive.
Memory appears to be highly selective for
what is most relevant in a given situation.
• If you go for a hike and come upon a snake,
you will tend to remember things like:
− Don’t move quickly
− Look and listen for a rattle
• You don’t immediately start to remember trivialor irrelevant facts about snakes:
− Snakes are heterothermic
− Snakes hibernate
− “Snake” rhymes with “rake”
Taken together, cognitive systems need to overcome
complexity using a variety of innate and learned biases.
Some biases are
species-specific and reflect an animals
evolutionary adaptation to their ecological niche.
Different cognitive systems (e.g. attention, learning, and memory)
may have
different limits and constraints.
Cognitive Psychology:
To characterize how each cognitive
system operates, it is helpful to study the biases and tendencies of the system.
− With a complete functional account of how a system operates, you can make testable predictions and build detailed models
of the system and how they will work in the future.
− THEN you can them examine how the brain implements these models.
Which of the following is NOT true of cognitive
biases:
They are always innate.
because bias can be learned (top-down)
Franciscus Donders (1868)
performed one of the first experiments that would be considered cognitive psychology:
• Empirical: He wanted to know how long (physical measurement) it took for a person to make a decision (what happens in your head?).
• He performed a reaction-time (RT)
experiment that compared two conditions:
− Simple RT: Push a button as quickly as possible in response to a light. PERCEPTION
− Choice RT: Push one button if the light is on the right side, another button if it is on the left side. DECISION
took the difference: Choice RT - Simple RT = how long it took for the decision to be made
Donders’ reaction-time experiments were remarkable for a few reasons:
3
- It was the first use of a behavioral measure to infer a mental process. This is known as mental chronometry.
• This is (still) a basic paradigm in all of experimental psychology and cognitive neuroscience.
- The underlying assumption was that the mental processes were resource-limited (i.e. they need time to work).
• This was somewhat novel and is still a basic assumption today.
- KEY: The subtraction method put mental events on the same basis as physical events.
• This subtraction method is the basis of comparison for fMRI, EEG, MEG, and other modern recording methods.
mental chronometry
use of a behavioral measure to infer a mental process
still foundational for all Cognitive Science experiments (measurements of reaction times)
subtraction method
is the basis of comparison for fMRI, EEG, MEG, and other modern recording methods
find what was unique
Hermann Ebbinghaus (1885)
wanted to understand the nature of memory and how we forget.
• Using himself as his subject, he repeated
lists of nonsense syllables (e.g. DAX, YAT,
ZIF, etc) and determined how long it took
him to learn the entire list.
• He then waited some (variable) amount of
time and then measured how long it took
him to re-learn the list. (if it took you 5 minutes the first time and 2 minutes the second time then there was some saving of memory; if it took 5 minutes the first time and 5 minutes the second time you didn’t learn anything)
• He wanted to know if the length of the
delay affected how much was forgotten.
Ebbinghaus and memory
Ebbinghaus found that memory for the syllables dropped steeply with increasing time.
- This was the first experimental quantification of memory and showed that mental properties could fit a mathematical curve (!!! this makes a formula is a model that allows you to make predictions).
- As with Donders, this was an example of using behavioral measures to infer something about mental properties.
limits of Ebbinghaus’s experiment
using himself as a subject limited the external validity of the
experiments – it couldn’t be shown that the effect would hold for other people.
The first experiments in cognitive psychology were based on the idea that mental responses can be:
inferred from the participant’s behavior
NOT MEASURING MENTAL PROCESSES
MEASURING CORRELATED BEHAVIOR AND THEN INFERR SOMETHING ABOUT THE MENTAL PROCESS UNDERNEATH
NEVER DIRECTLY MEASURING THE MENTAL EVENT: CAN’T OBJECTIVELY MEASURE
even recording from a single neuron - it’s still behavioral: measuring brain behavior (mind is not necessarily in the brain)
Wilhelm Wundt
started the first laboratory for psychological research in 1879.
structuralism - maybe thoughts have basic units like atoms or molecules
• His believed that mental processes could be
broken down into basic elements or fundamental units (sensations).
Wilhelm Wundt trained people to use analytic
introspection –
a descriptive technique that required subjects to describe their experiences and thought processes using a standardized vocabulary.
trying to get better access to those mental events and not make an appeal to behavior
e.g. if you were angry you were given 5-10 terms to describe your anger and then given a scale
Wilhelm Wundt hoped to get
direct access to mental phenomena and not need to infer processes from behavioral responses.
Wilhelm Wundt’s results
BIG PROBLEMS: were highly variable between individuals: the intensity of one person’s headache vs. the intensity of another person’s: we don’t have some object basis for determining this
The method also could not give an account of unconscious inferences (intuitions, bias): how do you get access to these things if they’re not in your mental awareness?
John B. Watson
was an early psychologist who was interested in animal and infant learning.
• He was critical of Introspectionism due to its
extreme variability in results. He also
questioned how results could be verified and tested, does it repeat, can you get same results across individuals?
− Internal processes are ‘invisible’ and
cannot be objectively measured or replicated.
• wanted to re-structure psychology entirely: “What we need to do is to start work upon
psychology, making behavior, not
consciousness, the objective point of our
attack.”
you can’t trust the mental, you don’t know what’s really there, all you have is behavior
Watson proposed a new approach called behaviorism.
• All topics of interest had to be given operational definitions – specific operations that were objectively observable.
− can’t talk about ‘Hunger’ = instead absence of eating for 24 hours (quantify and compare between people)
− ‘Memory’ = repetition of trained behavior
- ‘Mental’ entities were no longer valid topics of study.
- “Its theoretical goal is the prediction and control of behavior.”
Behaviors no longer allowed inference to an internal state.
Behaviors were, themselves, the thing of interest.
radical change! and very influential!
