Class Notes: Chapter 4

What Does It Mean To Be Interdisciplinary?

Is there such a thing as cognitive science (as opposed to the cognitive sciences)?
Does cognitive science have a distinctive methodology?
Or is it merely a collection of separate disciplines (all talking to each other, or past each other)?

Chapter 4: Section 4.1

What are the advantages of an interdisciplinary approach to cognitive science (or any other discipline)?

Are there any dangers that come with an interdisciplinary approach? How can we avoid them?

Possible advantages:
The mind is too complicated to be understood using the resources of any one discipline alone
The mind needs to be (can be?) understood at many different levels

Possible problems:
Interdisciplinary interference? Political conflicts?

Chapter 4: Section 4.2

Describe the difference between how psychology and neuroscience are organized.

Neurosciences: Levels of organization and explanation

Experimental psychology
Cognitive and Behavioral neuroscience
Systems neuroscience
Cellular neuroscience
Molecular neuroscience

Organization of the NeuroSciences
Churchland & Sejnowski: Tools organized by space and time

Organization of Psychology
By topical domains. No hierarchy of levels.

Chapter 4: Section 4.4

Case history in integration: Reasoning and rational judgment

Much research in this area has compared human judgment with normative models
Departures from the normative model may indicate “irrational” thinking
Thirty years of argument over the issue might be settled by integrating evolution theory, math models of game theory, and cognitive resrach

Two Views of Rationality

“What a piece of work is man. How noble in reason, how infinite in faculties, in form and moving how express and admirable, in action how like an angel. In apprehension how like a god. The beauty of the world, the paragon of animals”.
William Shakespeare, 1603

“The capacity of the human mind for formulating and solving complex problems is very small compared with the size of the problems whose solution is required for objectively rational behavior in the real world—or even for a reasonable approximation to such objective rationality”.
Herbert Simon, 1957.

An Example of Irrational Behavior?

Subscription offer from The Economist:
Internet only, for one year $59
Print only, for one year $125
Print plus internet, one year $125
Why would they provide the middle offer? (Dan Ariely, Predicable Irrationality)

Why are logic and probability theory considered to be domain-general?

Logic and probability are abstract normative theories
As such, they apply to any phenomenon that can be described in terms of the fundamental elements
P[A or B] = P[A] + P[B] – P[A and B]: It does not matter what A and B are.

Describe the original Wason selection task.

Hypothesis: “Cards with a ‘B’ on one side have a number 21 or greater on the other side”.
Which of these cards must you turn over to see if the hypothesis is false?

What is a deontic conditional? Give your own example of one.

The Law: “Anyone drinking beer must be 21 or older”.
Which of these people must you check to see if the law has been broken

Cassava root studies (Cosmides and Tooby)
Background about (imaginary) Pacific island:
Only married men have facial tattoos
Cassava roots are a highly prized delicacy and aphrodisiac
Molo nuts are bitter and not valued in the community
(Assume these are known facts)

Deontic versus Non-Deontic Rules

Non-Deontic Rule: Married men live on the side of the island where cassava roots grow, while unmarried men live on the side where the molo nuts grow
Deontic Rule: Only married men have the right to eat cassava roots.
“If a man is eating cassava root, he must have a tattooed face”

Descriptive (non-deontic) version: Poor performance (21%)
Social exchange (deontic) version: Better performance (75%)

Reconstruct Cosmides and Tooby’s argument for the cheater detection module.

Social exchange version has following structure:
If one wants to benefit from an exchange, then there is a cost.
A cheater is one who tries to obtain benefit without cost
It is socially adaptive to be able to detect cheats readily

Do Cosmides and Tooby give a successful explanation of the experimental results from versions of the Wason selection task? Have they made a good case for the cheater detection module?

The issue of modularity has been a controversial one
But considerable evidence supports the “cheat detector” hypothesis

Another Test of the Cheat Detector Hypothesis

An experiment by Gigerenzer & Hug:
“If an employee works during the weekend then that person gets a day off during the week”
Subjects took either the worker perspective or the employer perspective
What choices would you expect?

Describe a prisoner’s dilemma.

Prisoner’s dilemma illustrates the basic structure of interactions where being a free rider is advantageous
The dominant strategy for each play is to DEFECT
But mutual defection is sub-optimal

What is the TIT FOR TAT strategy? Why do evolutionary psychologists think it might provide a way of explaining the emergence of cooperative behavior?

Axelrod’s computer tournament: Highest average score came from TIT-FOR-TAT
Shows how cooperative behavior might emerge in very simple organisms

Some evidence that TIT-FOR-TAT is followed in the animal kingdom (Vampire bats, 3-spined sticklebacks)
Has been used to model complicated human interactions (e.g. voting patterns in US Senate)
TIT-FOR-TAT can only work if there is a reliable mechanism for detecting cheaters

Outline the local integration presented in Section 4.4.

Solution of adaptive problems Explains Emergence of dedicated cheater detection system Explains Patterns of error in logical reasoning tasks
Psychology, Evolutionary biology, and Mathematics of game theory work together to address a specific phenomenon

Chapter 4: Section 4.5

Briefly describe how fMRI works. Compare it with PET.

PET measures cerebral blood flow by tracking the flow of water labeled with a radioactive isotope
Basic assumption – local blood flow within the brain is related to cognitive function
The correlation between cognitive function and blood flow has been well documented since 19th century

fMRI measures levels of blood oxygenation - an indirect measure of blood flow
Cognitive activity correlated with increased cellular activity correlated with increase blood oxygen levels [supply exceeds demand]
BOLD contrast is the contrast between oxygenated and deoxygenated blood

Why do we need the local integration between neural activity and the BOLD signal?

How do we move from coarse-grained correlations between blood flow and cognitive activity to an understanding of how cognitive activity takes place?
We want to know not just where cognitive activity is happening, but how it is happening
Requires calibrating imaging data with data about neural activity

Neuroimaging allows us to identify which brain areas are active when subjects perform particular tasks
But there is a difference between localizing cognitive activity and explaining or modeling cognitive activity
What is the neural activity that generates the BOLD contrast?

What are some hypotheses about the source of the BOLD signal?

The large-scale activity results from the collective activity of large numbers of individual neurons – but how?
BOLD signal may be correlated with the firing rates of populations of neurons
BOLD signal may be correlated with the inputs to neurons

Outline the local integration presented in Section 4.5.

Logothetis et al (2001) measured the BOLD signal in monkeys at the same time as measuring (a) spiking activity of neurons and (b) local field potentials (LFP: measure of input to the neuron)

The neural correlate of the BOLD signal is LFP
LFP is not the dimension of neural activity most frequently measured in single neuron studies
We don’t know much about the connection between LFP and cognition
But we do have the beginning of an integration between levels of neuroscience: Single neuron and aggregates of neurons