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Dread and the Disvalue of Future Pain

Figure 5

Model comparison and framing effects: Experiment 1.

A: Bayesian Information Criterion (), summed across participants (N = 25) for the alternative models. Lower values of indicate better fits of the model. Exponential Dread outperformed other models, with Undiscounted Exponential Dread providing the most parsimonious fit at the group level, indicated by the red circle. B: Mean frequency of choosing sooner pain across all choices by all participants in either frame. Error bars show one standard error from the mean in each direction. Two-tailed paired t-test showed significant difference between the two frames t(32) = 2.84, p = 0.0077. This result was confirmed with non-parametric testing for differences between paired samples using the Wilcoxon Signed Rank test, which revealed significant differences between the two medians (N = 33, Z = −2.6, p = 0.0093). C: Results of fitting the general form Exponential Dread model to both pain and relief frames, whilst restricting which parameters were allowed to vary between frames. In the unrestricted framing model (All-Framing) all four parameters, the inverse softmax temperature, , the discount parameters, and , and the anticipation parameter, , were applied separately to each frame, yielding an eight parameter model. In the fully restricted framing model (No-Framing) all parameters were constrained to be equal across frames, yielding a four-parameter model. The best fit, indicated by the red circle, was provided by a four-parameter model in which , and were fixed across frames, leaving between-frame differences explained by differences in (-Framing). Likelihood ratios are displayed at both the group level and the individual level, strongly favoring the -Framing model over the No-Framing model at both the group (fixed effects) (LR = 10¹⁰⁸∶1, χ2 = 497.3, p<0.001, d. f. = 25) and individual levels (Mean individual LR = 2088∶1, χ2 = 19.9, p<0.001, d. f. = 1) .

doi: https://doi.org/10.1371/journal.pcbi.1003335.g005