Belief bias in conditional reasoning - an fMRI study.

Matt Roser, Jonathan Evans, Nick McNair, Giorgio Fuggetta, Dries Trippas

RES-062-23-3285

Title

Jonathan Evans

Giorgio Fuggetta

Marie-Stephanie Cahart

Nick McNair

Lucas Michaelides

Dries Trippas

Belief bias in conditional reasoning - an fMRI study. Collaborators

• Many cognitive biases influence reasoning and decision making

• Performance on reasoning tasks often diverges from normative correctness but at least some people can reason analytically on these tasks

• We studied Belief Bias in conditional reasoning. This is manifest as a tendency to endorse more inferences derived from believable conditional statements, regardless of logical validity

• In the dual-process framework – type 1(intuitive) processes cause the belief bias which may or may not be overridden by type 2(reflective) processes

• Individuals of higher cognitive ability (and WMC) are more likely to inhibit the effects of believability in conditional reasoning, under the right conditions

Intro to BB

Belief bias in conditional inference

• We studied conditional reasoning while scanning with fMRI - In addition, we collected IQ, working-memory and measures of rational thinking disposition from all of our participants • Research questions - what neural systems are involved in conditional reasoning?

- how is believability processed in the brain? - what distinguishes those more or less susceptible to belief bias in terms of

neural activity?

- in particular, do those showing less belief bias, show more evidence of inhibition and/or more evidence of engagement of analytic reasoning

Intro to BB

Method and research questions

• Right Inferior Frontal Gyrus (IFG) – inhibition • Dorsolateral prefrontal cortex (DLPFC) – working memory • Ventromedial cortex – belief

• VLPFC and connected posterior (temporal) areas

Brain areas of interest

Harris, Kaplan, Curiel, Bookheimer, Iacoboni, & Cohen (2009). PLoS One, 4(10), e7272.

Goel, & Dolan (2003). Cognition, 87(1), 11-22.

Barbey, Koenigs & Grafman (2013). Cortex, 49(5), 1195-1205.

O’Reilly, R. C. (2010). Trends in neurosciences, 33(8), 355-361.

Brain areas of interest

Believable MP

If car ownership increases then traffic congestion will get worse

Car ownership increases

Therefore, Traffic congestion gets worse

---

Believable DA

If jungle deforestation continues then gorillas will become extinct

Jungle deforestation does not continue

Therefore, gorillas do not become extinct

Unbelievable MT

If fast food is taxed then childhood obesity will increase

Childhood obesity does not increase

Therefore, fast food is not taxed

---

Unbelievable AC

If the lottery prize-money increases then fewer people will buy tickets

Fewer people buy tickets

Therefore, lottery prize-money increases

• Three-term conditional statements comprised the Major Premise (MajP), Minor Premise (minP), and Conclusion (C)

• Conditionals described causal relationships about the world

• Half of the MajP statements were ‘believable’, half ‘unbelievable’

Stimuli and Task Stimuli

• N = 51

• 72 x experimental trials in 3 x blocks of 24 – Half Un/believable

– Half In/valid

– Each MajP was shown twice: 1 x Valid and 1 x Invalid

• 36 x baseline-task trials in 2 x blocks of 18

Stimuli and Task

Exp BL Exp BL Exp

Task

A trial

• Split presentation allows separation of the sentence containing the belief content (the major premise) from the content that allows reasoning to begin (the minor premise and conclusion)

Major Premise

+

1 sec

4-6 sec

Major Premise

Minor Premise

Conclusion

Response

+

3-5 sec

Confidence

Response

Task2

Reasoning Condition:

• Participants shown an example

• Assume the premises are true

• Determine whether the conclusion must necessarily follow by logic

• Two-button choice response – 15 seconds

Baseline Condition:

• Participants shown an example - three unrelated premises

• Check for repetitions of verbs – one versus none or two

• Two-button choice response – 15 seconds

Instructions Instructions

Baseline statements

If jungle deforestation continues then gorillas will become extinct

Foreign investment is encouraged

Therefore, Prince Charles will become the king

If fertility treatment improves then the world population will rise

Sea levels rise

Therefore, business practices will improve

“YES”

“NO”

Baseline

• A tendency to treat inferences from believable conditionals as logically valid was observed

Acceptance Rates: Overall

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100

MP MT AC DA Overall

Believable

Unbelievable

MP MT AC DA Overall

Believable 97.6 43.7 43.1 75.6 65.0

Unbelievable 90.1 34.3 36.6 61.5 55.6

Belief: F(1,49)= 25.80, p< .001

Form: F(3,147)= 80.24, p< .001

MP > DA > AC = MT

Acceptance rates

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MP MT AC DA Overall

Believable

Unbelievable

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MP MT AC DA Overall

Believable

Unbelievable

Low IQ High IQ

Belief*IQ: F(1,49)= 5.35, p= .025

Low IQ: Believable > Unbelievable

High IQ: Believable = Unbelievable

Form*IQ: F(3,147)= 6.53, p= .001

Low IQ: MP > DA = AC = MT (DA > MT)

High IQ: MP > DA > AC = MT

Acceptance Rates: Low / High IQ Low/High IQ

IQ and Belief Bias

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-10

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80 90 100 110 120 130

Be

lief

Bia

s

WASI IQ Score

Pearson’s r: -.31 (p< .05)

IB and BB correlation

Major Premise

+

1 sec

4-6 sec

Major Premise

Minor Premise

Conclusion

Response

+

3-5 sec

Confidence

Response

BOLD modelled for major premise (P1) and for entire argument (PALL)

fMRI Data Model Model

• Reasoning Task > Control for Major premise (P1) and Entire Argument (PAll)

• Contrasted Believable/Unbelievable for Major premise and Entire Argument • Correlate Belief-Bias index with extracted signal strength for each ROI

• Correction for Multiple Comparisons

– Voxel-level: p < .001 uncorrected

– Cluster-level: p < .05 FDR corrected

Processing and Analyses • High-pass filter – cutoff 128s • Smooth with a 6mm FWHM kernel • Normalisation to MNI template • Six motion regressors were included (3x translation; 3x rotation) • Temporal derivatives not included • Four subjects excluding from analysis due to functional/movement artifacts • Three subjects excluded on behavioural grounds (accepted or rejected all)

Processing and analysis

P1 > Control Task

Left Middle Temporal gyrus – Temporal pole Left Inferior Parietal cortex - Angular gyrus Left Inferior Frontal cortex (BA 44) R Hemisphere homologues show lesser activity Left SMA, Dorsomedial PFC Bilateral ventromedial frontal Right Inferior frontal (BA 45)

P1 > Control contrast

P1: Unbelievable > Believable Left and Right Inferior Frontal Gyrus Right more ventral BA 45/47 Left TPJ

Ventral and Dorsal Anterior cingulate

P1: Believable > Unbelievable

P1 Believability contrast

PAll > Control Task

PAll: Unbelievable > Believable

Left Dorsolateral PFC BA 44 BA 8 and BA 9

Left and right middle frontal gyrus BA 44/45 Left and right parietal lobe

PAll Believability contrast

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Belief Bias: PAll Unbelievable > PAll Believable

Left PPC

Left MFG

Pearson’s r: .512 (p< .001)*

Pearson’s r: .613 (p< .001)*

Index of belief effect: Believable – Unbelievable endorsement rates

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Right PPC

Right MFG

Pearson’s r: .642 (p< .001)*

Pearson’s r: .591 (p< .001)*

Index of belief effect: Believable – Unbelievable endorsement rates

Belief Bias: PAll Unbelievable > PAll Believable

• Lateral inferior-frontal areas were differentially active according to the believability of the major premise

• Involvement of representational and inhibitory mechanisms at an early stage of the trial invoked by the presentation of belief-laden material when participants are instructed to reason deductively.

• Dorsolateral prefrontal and parietal regions were differentially activated by believability when all premises available for inference

• Individual differences in the degree of belief bias correlated strongly with functional activation in DLPFC and PPC at the later stage of the trial.

• Individual differences in the degree of belief bias are reflected in later processes of premise integration which draw heavily on working memory.

• Areas show greater activity with unbelievable materials – demands on them are greater when reasoning with unbelievable material.

• People who are more susceptible to belief bias show a greater degree of differential demand on these regions when believability is manipulated.

Summary

• These results are consistent with dual-process accounts of reasoning. They imply an initial processing of belief that is actively inhibited (according to instructions) but which can determine responses if WM- demanding processes are insufficient Believability modulated activity in IFG/Temporal network and DLPFC/Parietal network under different stimulus conditions (P1,PAll) Locus of BB effect in latter stage of premise integration and manipulation (PAll), which draws heavily on WM and activates DLPFC/PPC, consistent with negative correlation between IQ/WM and BB.

Conclusions

Reinstatement of inference in opposition to belief Greatest in high IQ, leading to less BB Low IQ experience relatively greater demand on WM resources when reasoning with unbelievable materials and are less able to reinstate the valid inference

Inference follows

No

Withhold

Yes

Believable?

Yes

Draw

No

Withhold

Check reasoning

Yes

Reinstate Draw

No Withhold

Within-trial rTMS in Conditional Reasoning TMS

Within-trial rTMS in Conditional Reasoning • Investigate stages of Major-Premise (MajP) processing (believability apparent) and

Minor-Premise (minP) (Between subjects) • Investigate functional regions such as DLPFC (working memory) and IFG (inhibition),

informed by group fMRI de-normalised to individual

Cross these two factors in a 2x2 design: MajP – IFG MajP – DLPFC minP – IFG minP – DLPFC • MajP - Decontextualisation of materials and the suppression of belief may occur

following the MajP. • minP - Effortful combination of premises and the derivation of a conclusion • An effect of rTMS over IFG for MajP, but not for minP, coupled with an effect of rTMS

over DLPFC for minP but not for MajP would doubly dissociate the MajP and minP stages and inform on processing in conditional reasoning

…

0 -1000 -500

…

If DEAD then BREATHING (1 sec) DEAD (1 sec) BREATHING

Major premise

Minor premise

Conclusion

(Consequent)

Within-trial rTMS in Conditional Reasoning