Table 1.
Summary of models analyzed to account for the influence of ambiguity and second-order uncertainty on choice (see also Fig. 3)
| Models accounting for ambiguity | Models accounting for ambiguity and second-order uncertaintya | ||
|---|---|---|---|
| Baseline | Baseline (ideal observer) model, assuming the reduction of compound lotteries axiom and taking into account the silhouette position for the calculation of expected outcome probability | Baseline SOP | Baseline SOP weighting model without additional parameters to account for entropy |
| Utility weighting | Utility weighting model, using different utility functions for ambiguous and nonambiguous decisions | Utility weighting | Utility weighting model, assuming modulation of the utility function in ambiguous trials |
| EU weighting additive | Expected utility additive weighting model, adding a constant to the expected utility of ambiguous choices | EU weighting additive | Expected utility additive weighting model, adding a variable amount to the expected utility of ambiguous choices |
| EU weighting multiplicative | Expected utility multiplicative weighting model, multiplying the expected utility of ambiguous choices with a constant | EU weighting multiplicative | Expected utility multiplicative weighting model, multiplying the expected utility of ambiguous choices with a variable |
| Ep weighting | Expected probability weighting model, nonlinearly weighting the expected probabilities in ambiguous choices by exponentiating them with a constant (Hsu et al., 2005) | Ep weighting | Expected probability weighting model, exponentiating expected outcome probability of ambiguous choices with a variable |
| Pessimistic weighting | Pessimistic weighting model, biasing the second-order probabilities toward the worse scenario in ambiguous choices (Ghirardato et al., 2004; Huettel et al., 2006) | Pessimistic weighting | “Pessimistic” weighting model, overestimating/underestimating the second-order probability of the worse scenario |
| Minimax | Minimax model, where choice in ambiguous trials is based on the worse scenario only | Not applicable | |
| SOP | SOP model, in which the conditional expected outcomes are nonlinearly weighted before being combined with the unbiased second-order probabilities into an expected outcome (Segal, 1987; Klibanoff et al., 2005) | Combined SOP | Combined SOP model, in which the second-order probabilities are additionally weighted by entropy |
aBased on the second-order probability (SOP) model, additional models were formed that accounted for entropy within ambiguous choices by having an additional free parameter that is modulated by mean-centered entropy. EU, Expected utility; Ep, expected probability.