The Magnitude Heuristic: Larger Differences Increase Perceived Causality.

The article focuses on the "magnitude heuristic," a cognitive bias whereby consumers infer that relationships between variables with larger perceived magnitudes are more likely to reflect true causal effects, even when correlations are held constant or the relationships are spurious. Through seven studies, the research demonstrates that consumers rely on this heuristic across various contexts, including health-related decisions, and that normatively irrelevant factors—such as the units of measurement, graphical presentation, and reference points—can distort perceived magnitudes and thus causality judgments. The findings highlight that exposure to large-magnitude but noncausal relationships, increasingly common due to big data and machine learning, can lead to systematic biases in consumers' judgments and subsequent purchase or consumption decisions. This research contributes novel insights into how magnitude perceptions influence causality judgments beyond correlation and underscores important implications for marketing, consumer welfare, and decision-making in domains where causal inference is critical.