Belief bias in conditional reasoning - an fMRI study.
Matt Roser, Jonathan Evans, Nick McNair, Giorgio Fuggetta, Dries Trippas
Title
RES-062-23-3285 Collaborators Belief bias in conditional reasoning - an fMRI study.
Jonathan Evans Nick McNair
Giorgio Fuggetta Dries Trippas
Marie-Stephanie Cahart Lucas Michaelides Belief bias in conditional inference Intro to BB
• 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
Method and research questions Intro to BB
• 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 Brain areas of interest Brain areas of interest
• Right Inferior Frontal Gyrus (IFG) – inhibition
Goel, & Dolan (2003). Cognition, 87(1), 11-22. • Dorsolateral prefrontal cortex (DLPFC) – working memory
• Ventromedial cortex – belief
• VLPFC and connected posterior (temporal) areas
Barbey, Koenigs & Grafman (2013). Cortex, 49(5), 1195-1205.
O’Reilly, R. C. (2010). Trends in neurosciences, 33(8), 355-361. Harris, Kaplan, Curiel, Bookheimer, Iacoboni, & Cohen (2009). PLoS One, 4(10), e7272. Stimuli and Task
Stimuli • 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’
Believable MP Unbelievable MT If car ownership increases then traffic If fast food is taxed then childhood obesity will congestion will get worse increase Car ownership increases Childhood obesity does not increase Therefore, Traffic congestion gets worse Therefore, fast food is not taxed ------Believable DA Unbelievable AC If jungle deforestation continues then gorillas If the lottery prize-money increases then fewer will become extinct people will buy tickets Jungle deforestation does not continue Fewer people buy tickets Therefore, gorillas do not become extinct Therefore, lottery prize-money increases Stimuli and Task Task • 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
Exp BL Exp BL Exp A trial Task2
Major Major Premise Premise + Minor Confidence +
Premise
Conclusion
1 4-6 Response Response 3-5 sec sec sec
• 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) Instructions
Instructions
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
Baseline Baseline statements
“YES”
If jungle deforestation continues then gorillas will become extinct Foreign investment is encouraged Therefore, Prince Charles will become the king
“NO”
If fertility treatment improves then the world population will rise Sea levels rise Therefore, business practices will improve Acceptance Rates: Overall Acceptance rates
• A tendency to treat inferences from believable conditionals as logically valid was observed
MP MT AC DA Overall Belief: F(1,49)= 25.80, p< .001 Believable 97.6 43.7 43.1 75.6 65.0 Form: F(3,147)= 80.24, p< .001 Unbelievable 90.1 34.3 36.6 61.5 55.6 MP > DA > AC = MT
100 90 80 70 60 50 Believable 40 Unbelievable 30 20 10 0 MP MT AC DA Overall Acceptance Rates: Low / High IQ Low/High IQ
Belief*IQ: F(1,49)= 5.35, p= .025 Form*IQ: F(3,147)= 6.53, p= .001 Low IQ: Believable > Unbelievable Low IQ: MP > DA = AC = MT (DA > MT) High IQ: Believable = Unbelievable High IQ: MP > DA > AC = MT
100.0 90.0 100.0 90.0 80.0 80.0 70.0 70.0 60.0 60.0 50.0 Believable 50.0 Believable 40.0 Unbelievable 40.0 Unbelievable 30.0 30.0 20.0 20.0 10.0 10.0 0.0 0.0 MP MT AC DA Overall MP MT AC DA Overall Low IQ High IQ IQ and Belief Bias IB and BB correlation
50
40
30
20 Pearson’s r: -.31 (p< .05)
10 Belief Belief Bias
0 80 90 100 110 120 130 -10
-20 WASI IQ Score fMRI Data Model Model
BOLD modelled for major premise (P1) and for entire argument (PALL)
Major Major Premise Premise + Minor Confidence +
Premise
Conclusion
1 4-6 Response Response 3-5 sec sec sec Processing and analysis 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)
• 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 P1 > Control Task
P1 > Control contrast
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: Unbelievable > Believable
P1 Believability contrast Left and Right Inferior Frontal Gyrus
Right more ventral BA 45/47
Left TPJ
P1: Believable > Unbelievable
Ventral and Dorsal Anterior cingulate PAll > Control Task
PAll Believability contrast Left Dorsolateral PFC
BA 44
BA 8 and BA 9
PAll: Unbelievable > Believable Left and right middle frontal gyrus BA 44/45
Left and right parietal lobe Belief Bias: PAll Unbelievable > PAll Believable Index of belief effect: Believable – Unbelievable endorsement rates
Left MFG
0.5 0.4 0.3 0.2 Pearson’s r: .613 (p< .001)* 0.1 0 -20 -0.1 0 20 40 60 -0.2 -0.3
Left PPC
0.6 0.5 0.4 0.3 0.2 Pearson’s r: .512 (p< .001)* 0.1 0 -20 -0.1 0 20 40 60 -0.2 Belief Bias: PAll Unbelievable > PAll Believable Index of belief effect: Believable – Unbelievable endorsement rates
Right MFG
0.5
0.4 0.3 Pearson’s r: .642 (p< .001)* 0.2
0.1
0 -20 0 20 40 60 -0.1
-0.2
Right PPC 0.4
0.3
0.2 0.1 Pearson’s r: .591 (p< .001)* 0 -20 0 20 40 60 -0.1
-0.2 • Lateral inferior-frontal areas were differentially active according to the believability of the major premise Summary
• 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.
Conclusions • 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.
Inference follows Reinstate Draw
No Yes Yes
Withhold Check Believable? reasoning No Withhold
Yes No
Draw Withhold
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
TMS Within-trial rTMS in Conditional Reasoning 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 Within-trial rTMS in Conditional Reasoning
If DEAD then BREATHING Major premise (Consequent) (1 sec)
DEAD Minor premise
(1 sec)
BREATHING Conclusion
… … -1000 -500 0