PSY270H1 Lecture Notes - Lecture 2: Resting Potential, Lobes Of The Brain, Frontal Lobe
Lecture 2:
Types of Studies:
Observational Studies – No random assignment of individuals to our experimental conditions.
Third variable problem (we don’t know if the result is correlation, if there is some third variable
influencing both)
Experimental Study – Randomly assign student to two groups. The issue is when your
manipulating one thing you may be manipulating another construct instead/in tandem. You can
assume causation if there aren’t additional confounds.
Experimental Design Conditions:
Dependant Variable: The variable that is measured in the experiment
(important question is how you decide to operationalize the variable?)
Independent Variable: The variable that is manipulated in the experiment. How do you
manipulate naps? Within vs. Between subject design? Between is like one groups take nap and
one not and Within is like you have one group take two tests first with nap and then without
nap.
Confounding Factors: Uncontrolled variables that could also influence the dependent variable.
A variety of statistical analyses are used in cognitive psychology.
Their basic aim is to determine how likely the results of an experiment are to occur by chance.
If it is sufficiently unlikely that a result occurred by chance (<5%) the independent variable is
said to have a “statistically significant” effect on the dependent variable. You can use both
within one study.
Other statistical inference notes are on slides.
Different types of error bars:
If 95% confidence intervals don’t overall results pass standard thresholds (but can be significant
if they overlap a bit)
If standard error bars overlap results are not significant (but they need to be quite distant to be
significant).
Ceiling Effect: dependant variable is not sensitive to manipulation because performance is
already so high.
Floor Effect: dependant variable is not sensitive to manipulation because performance is
already so low.
Specific research designs also on slide
Neuro Anatomy
Why study the brain to understand cognition:
The same cognitive question can be answered in different ways ‘
David Marr outline 3 levels of analysis.
1) Computational level (broadest): What does the process do and why does it do it?
2) Algorithmic level (intermediate) how does the problem work? What are its specific
inputs, outputs, and representations?
3) Implementation (specific); How is the process physically manifested in the brain?
Our nap example could have hypothesis at each level of analysis:
1) The function of sleep is to strengthen important new memories
2) Important, newly-formed memories are integrated with existing long-term memories
during sleep, strengthening their representations and increasing their accessibility.
3) The hippocampus replays important, newly-formed memories during slow-wave sleep,
strengthening their representations in the cerebral cortex.
Understanding how the brain supports cognition at an implementation level can give insights
into how cognition works at computational and algorithmic levels:
If two cognitive abilities are neutrally independent, we can assume that they are cognitively
independent.
Long-standing cognitive debates often can’t be resolved by behaviour alone – sometimes neural
findings show that both theories are right, just implemented in different parts of the brain.
Discoveries in the brain can give us new clues about how cognition works.
Neurons:
Santiago Cajal discovered that the brain is made up of distinct calls; led to the Neural Dotorine
Images on slides
Interpretation that brain was like network of highways
Part of the reason for that is that neurons are so densely packed together that when you try to
visualize them all at once you can’t see the spaces between them. However, if you look at a
small proportion of Neurons within a slice using mechanisms such as a the golgi stain you can
see the spaces between them.
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PSY270H1 Full Course Notes
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Document Summary
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