dissertation aaron tesch

A Tale of Two Systems: The effects of executive function on

UG DecisionsAaron Tesch

Rational Theories Of Decision-Making

Greeks: The spirt world is rational but our decisions are contaminated by the physical world.

I reject your offer !

Utility Theories

Absolute value ≠ Utility : St. Petersburg Paradox

Utility can't be calculated because of limitations of human cognition, therefore we use heuristics and have psychological biases.

However, still used in much of economic theory.

Two-System Decision Models

• Posner & Snyder (1975) and Schneider & Shiffrin, (1977) proposed two-systems models that pit a automatic system against a controlled system.

• Kahneman (2003) outlined such a theory:

• System 1 which automatically makes quick judgments based on simple heuristics and emotions

• System 2 which monitors the quality of the answer System1 produced and corrects it if necessary.

Neural Evidence for Two-System Decision models

• Delay Discounting (McClure)

• Moral Decision Making (Greene)

• Ultimatum game (Sanfey)

Other Two-System Models?

High vs. Low road visual processing- Ahh a bug!

Facial Expression- Say “monkey butts”

How do these systems relate to the decision systems?

Possible Neurological Evidence for Two system model in the UG

• Sanfey (2003) had people play the responder in a series of Ultimatum Games. Found higher activation in dlPFC than the Insula when accepting unfair offers and higher activation in the Insula when rejecting offers.

Priming Affective systems

• Harle & Sanfey (2007) found that rejection rates are reduced when primed with “sad” movie clips.

• Sadness = Insula activation? • Also disgusting clips may increase rejection rates!

TMS on the DLPFC

• Van ‘t Wout et al. (2005) and Knoch et al. (2006) both showed that TMS on the DLPFC increases acceptance rates during the Ultimatum Game.

• This suggests that the DLPFC is somehow, causally linked to decisions during the ultimatum game.

Working Memory is Associated with the DLPFC

Sakai, Rowe, & Passingham (2002) found that there was activation of DLPFC during correct working memory trials but not for incorrect working memory trials.

Pilot Experiment (WM-Easy)

• Two groups were given a UG task either with a working memory prime or without.

Results of Acceptance Rate Analysis

Acceptance rates in the easy working memory task were significantly higher then the control group with no working memory prime.

There was also a significant interaction. Acceptance rates also decayed slower in the working memory condition then in the control condition.

Pilot Experiment (WM-Hard)

• A harder working memory task that varied color, shape and location dimensions was used instead of the simple black dot task.

r=-0.44*

Results of Acceptance Rate Analysis

• Unfair acceptance rates were significantly negatively correlated with the error rates.

Trial by Trial Analysis

• A chi^2 showed that participants were more likely to reject on incorrect trials then on correct trials.

Limitations• How general is the System 2? Is it a general

executive functioning system, general working memory system, or is it limited to spatial working memory? We are not sure how the differences in memory task difficulty affect acceptance rates.

• Is loading the controlled system activating or depressing its function?

• Are their affective confounds due to memory task feedback?

Experiment 1

• Independent measures of spatial working memory (Visual Digit Span), verbal working memory (N-back), switching (Global-Local), inhibition (SSRT) and self reported general executive function (BADS).

• Also find the effect of different working memory difficulty levels on decisions.

• The No Feedback condition also allowed detection of emotional feedback confounds.

Visual Digit Span Task

• Adapted a digit span task to present 2-6 dots in a 3x3 grid instead of digits 1-9.

• Example with three dots →

750ms → 250ms blank

750ms → 250ms blank

750ms → 250ms blank

Ultimatum Game Trial

Picture → Proposal → Decision → Outcome

R T Y

F G H

V B N

Type of Trials

• Each participant received every combination of the five memory difficulty levels (2-6 dots) and the five UG Offer levels ($ 1-5).

D,O 2 3 4 5 6

1 2,1 3,1 4,1 5,1 6,1

2 2,2 3,2 4,2 5,2 6,2

3 2,3 3,3 4,3 5,3 6,3

4 2,4 3,4 4,4 5,4 6,4

5 2,5 3,5 4,5 5,5 6,5

Outcomes

• Updating but not switching or inhibition measures have positive relationship with System 2 decision making system.

• There is no within subject effects of working memory difficulty level.

• The trend for a relationship for visual digit span performance is dependent on memory feedback.

Experiment 2: Affective Processing due to unfair feedback• Unfair memory feedback

FeedbackR T Y

F G H

V B N

Outcomes

• Relationship between visual digit span reversed. Suggesting an emotional prime in proportion of unfairness experienced.

Experiment 3: Priming vs. Loading

• Is there any differences in UG decisions or EF relationships with those decisions after priming vs. loading the working memory system?

Condition Timelines

Condition WM Presentation Loaded task WM Test Unloaded task

Loading condition Dot Presentation → UG Trial → Dot Test → Control

Priming condition Dot Presentation → Control → Dot Test → UG Trial

Loading condition Priming condition

Outcomes

• The relationships between Updating and UG decisions that were not found in the other experiments were not found in the Priming condition.

• However, these relationships were not found in Loading control task either suggesting that the relationships mentioned above are fragile.

Overall Outcomes

• No System 2 effects of memory difficulty in the within subject paradigm but evidence of a good range of memory task difficulty.

• Fragile relationship between independent updating measures and UG decisions.

Discussion

• Little evidence supporting the connection of EF and System 2 decisions may suggest many interacting systems.

• However may simply be a limitation of the within subject paradigm.

Future Directions

• Between subject memory manipulations.

• How are decision related System 1 and System 2 related to other similar cognitive systems i.e. visual systems and expression systems?

• What are the outlines of the systems related to decision making?

• Can these models help explain preference reversals?