When Half Is at Least 50%: Effect of “Framing” and Probability Level on Frequency Estimates

Expert judgment often involves estimating magnitudes, such as the frequency of deaths due to a pandemic. Three experiments ( N s = 902, 431, and 755, respectively) were conducted to examine the effect of outcome framing (e.g., half of a threatened group expected to survive vs. die), probability level (low vs. high), and probability format (verbal, numeric, or combined) on the estimated frequency of survivals/deaths. Each experiment found an interactive effect of frame and probability level, which supported the hypothesis that forecasted outcomes received by participants were implicitly quantified as lower bounds (i.e., “ at least half”). Responding in a manner consistent with a lower‐bound “at least” interpretation was unrelated to incoherence (Experiments 1 and 2) and positively related to numeracy (Experiments 1 and 3), verbal reasoning (Experiment 3), and actively open‐minded thinking (Experiments 2 and 3). The correlational results indicate that implicit lower bounding is an aspect of linguistic inference and not a cognitive error. Implications for research on framing effects are discussed.