Mechanistic explanations are not immune to biased or heuristic processing

Teaser text: Mechanistic explanations are assumed to encourage careful reasoning about contentious scientific issues. In an experiment examining climate change and mask wearing, we found little evidence that participants systematically evaluated the causal logic of these explanations. Instead, most relied on heuristics, identity signaling, or other forms of engagement unrelated to the mechanism itself. These findings challenge common assumptions about how mechanistic explanations influence public understanding and suggest that explanation alone may not be enough to promote reflective engagement. Mechanistic explanations have been proposed as a way to reduce public ideological resistance to politicized scientific issues by directing audiences’ attention to the causal processes underlying scientific phenomena. In an online experiment, 507 U.S. participants viewed coherent or incoherent mechanistic explanations about climate change or mask-wearing, evaluated the strength of those arguments, and completed a thought-listing task. We assessed objective, systematic processing using 3 indicators: (a) differentiating between coherent and incoherent explanations in argument-strength evaluations, (b) identifying logical flaws in the incoherent condition, and (c) focusing thoughts on the explanatory mechanism. Participants generally failed to distinguish between coherent and incoherent explanations, only 5% identified flaws, and just 14% produced mechanism-focused thoughts. Instead, most participants exhibited identity-signaling, heuristic, or otherwise non-mechanistic responses, suggesting that mechanistic explanations do not reliably elicit the objective, systematic processing often assumed to underlie their effectiveness.