1. Neuroscience
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Model-based fMRI reveals dissimilarity processes underlying base rate neglect

  1. Sean R O'Bryan  Is a corresponding author
  2. Darrell A Worthy
  3. Evan J Livesey
  4. Tyler Davis
  1. Texas Tech University, United States
  2. Texas A&M University, United States
  3. University of Sydney, Australia
Research Article
Cite this article as: eLife 2018;7:e36395 doi: 10.7554/eLife.36395
6 figures, 2 tables and 2 additional files

Figures

Abstract task design and an example trial.

In the headings, I = imperfect predictor, PC = common perfect predictor, PR = rare perfect predictor. The second row refers to the visual category used for each stimulus feature: F = face, S = scene, O = object. Each following row corresponds to a learning trial, with a ‘1’ indicating the presence of the feature and ‘0’ indicating its absence.

https://doi.org/10.7554/eLife.36395.003
Learning curves.

Points depict proportions correct for common and rare disease predictions over the 12 blocks of the training phase (mean ± SEM). *p < 0.05.

https://doi.org/10.7554/eLife.36395.004
Figure 3 with 1 supplement
Multivoxel pattern similarity to common and rare stimulus features for ambiguous trials in which participants made common (left) and rare (right) responses (mean ± SEM).

Purple squares correspond to the objects/scenes associated with the common category, while green squares correspond to the objects/scenes associated with the rare category in a given trial. Gray squares depict mean pattern similarity to the non-present face dimension for both response types. *p < 0.05. No error bars are included for the gray bars because face dimensions were not included in the overall mixed effects model.

https://doi.org/10.7554/eLife.36395.006
Figure 3—figure supplement 1
Multivoxel pattern similarity to common and rare objects, scenes, and faces for ambiguous trials in which participants made common (left) and rare (right) responses (mean ± SEM).

Purple corresponds to objects/scenes associated with the common category, while green corresponds to the objects/scenes associated with the rare category on a given trial. Triangles indicate objects, and circles indicate scenes. Gray squares depict mean pattern similarity to the non-present face dimension for both response types. *p < 0.05. No error bars are included for the gray bars because face dimensions were not included in the overall mixed effects model.

https://doi.org/10.7554/eLife.36395.007
Multivoxel pattern similarity to each feature type during the learning phase (mean ± SEM).

The left panel is for trials predictive of a common disease, and the right for trials predictive of a rare disease. Red points represent perfect predictors, purple points represent imperfect predictors (faces), and blue points represent non-present features. **p < 0.01, ***p < 0.001.

https://doi.org/10.7554/eLife.36395.008
Associations between multivoxel pattern similarity to stimulus dimensions during the learning phase and individual differences in base rate neglect.

For each graph, the y-axis depicts the proportion of rare responses made by each subject on ambiguous test trials, while the x-axis depicts subjects’ mean BOLD pattern similarity to a respective stimulus dimension over the course of learning. **p < 0.01.

https://doi.org/10.7554/eLife.36395.009
Results from the model-based univariate analysis.

(A) Depicts activation that tracks similarity-based contributions to choice (summed similarity to the winning category). Red depicts activation positively correlated with similarity-based contributions and blue depicts negatively correlated activation. (B) Depicts brain regions that are positively correlated with dissimilarity-based contributions to choice (summed dissimilarity to the non-winning category).

https://doi.org/10.7554/eLife.36395.010

Tables

Table 1
Observed and dissGCM-predicted response probabilities for the test phase.

The feature combinations presented at test are listed in the leftmost column: F = face, S = scene, O = object. In the headings, D1–D4 correspond to the four possible category responses (diseases). Bold, italicized values indicate results for the key ambiguous stimuli in which a scene was paired with an object.

https://doi.org/10.7554/eLife.36395.005
BehaviordissGCM
Test itemD1D2D3D4D1D2D3D4
F1 + S1.972.018.008.003.971.014.008.008
F1 + O1.031.962.0080..063.901.018.018
F2 + O2.0050..987.008.008.008.972.013
F2 + S2.023.008.069.901.018.018.059.905
F1.667.295.023.015.667.283.025.025
F2.107.038.550.305.027.027.640.307
S1.848.061.008.083.955.015.015.015
O1.008.908.069.015.040.880.040.040
O2.008.069.908.015.012.012.965.012
S2.023.053.008.916.032.032.032.904
S1 + O1.414.487.073.027.419.496.042.042
O2 + S2.035.047.453.465.038.038.460.464
F1 + O2.131.238.6310..156.174.658.013
F1 + S2.264.062.008.667.178.237.023.563
F2 + S1.608.031.138.223.657.013.155.175
F2 + O1.008.674.302.016.024.567.170.239
O1 + O2.008.514.475.004.040.444.477.040
S1 + S2.397.065.011.527.400.040.040.520
Table 2
Activated clusters and peaks for the fMRI results in Figure 6.
https://doi.org/10.7554/eLife.36395.011
ContrastRegionsPeak t-valuePeak MNI coordinates (x,y,z)Number of voxelsCluster P
Similarity > 0
Rostral and ventral medial
prefrontal cortex
7.760, 54, –22268p<0.001
Middle temporal gyrus5.7464, –6, −141050p=0.016
Precentral gyrus7.6542, –16, 621031p<0.001
Precentral gyrus4.810, –30, 58463p=0.008
Middle temporal gyrus4.98−62, –2, −16322p=0.016
Parietal operculum cortex5.74−34, –30, 18282p=0.027
Hippocampus5.25−22, –18, −16271p=0.019
Lateral occipital cortex (inferior)4.6850, –72, 12157p=0.039
Similarity < 0
Superior parietal and lateral
occipital cortex (superior)
8.43−44, –46, 585123p<0.001
Middle frontal gyrus7.01−52, 12, 362491p<0.001
Dorsal medial PFC9.00−2, 18, 46917p<0.001
Cerebellum6.1128, –64, −28769p=0.002
Middle frontal gyrus6.2332, 2, 62730p=0.002
Middle frontal gyrus5.8944, 36, 30391p=0.009
Inferior temporal gyrus6.09−54, –52, −12375p=0.009
Inferior temporal gyrus6.5360, –52, −10271p=0.016
Cerebellum6.08−28, –60, −32186p=0.031
Thalamus4.88−10, –18, 10175p=0.038
Dissimilarity > 0
Occipital cortex7.5512, –78, 121372p<0.001
Fusiform and lateral occipital
cortex (inferior)
6.8242, –60, −18865p=0.002
Fusiform and lateral occipital
cortex (inferior)
5.97−36, –52, −18575p=0.003
Middle frontal gyrus5.0054, 16, 34255p=0.020
Frontal pole (rostrolateral PFC)5.93−42, 52, –6130p=0.047

Additional files

Supplementary file 1

Number of trials where common and rare responses were made for each participant over the 24 ambiguous scene-object test trials.

https://doi.org/10.7554/eLife.36395.012
Transparent reporting form
https://doi.org/10.7554/eLife.36395.013

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