Stacking multiple depolarization interventions does not amplify their effect on out-party warmth.

Evidence

Fig. 5 shows the results. First, there was no consistent effect of any single intervention relative to the control condition. While we do observe an increase in out-party warmth for all dosage amounts relative to the control condition (1 dose ATE = 3.82, SE 1.49; 2 dose ATE = 3.33, SE 1.49; 3 dose ATE = 5.31, SE 1.52), the effects are smaller in magnitude than those reported in the original MegaStudy, and we find no effects for any other outcome of interest. … Second, stacking interventions by exposing respondents to two or three treatments did not produce a significant additive effect compared to receiving a single intervention. These findings suggest that combining interventions in a single session fails to amplify their impact on reducing affective polarization or related attitudes. — Derek E. Holliday, Yphtach Lelkes, and Sean J. Westwood, Why Depolarization Is Hard, 61

Categorization

• SHARE: For a colleague working on polarization intervention scaling - direct counter-evidence to the assumption that more treatment doses are better.
• XREF: connects to: Even with identical panels, replicating Megastudy depolarization effects proved unreliable. — Derek E. Holliday, Yphtach Lelkes, and Sean J. Westwood, Why Depolarization Is Hard: Evaluating…, 76; Depolarization interventions can succeed while creating unintended harms.

Related

• Depolarization interventions barely raise out-party warmth and show no gains from repetition. (similarity 0.85)
• Even with identical panels, replicating Megastudy depolarization effects proved unreliable. (similarity 0.82)
• Depolarization interventions produce small, decaying effects that fail to scale or shift downstream attitudes (similarity 0.81)
• Depolarization interventions produce only modest temporary effects on partisan animosity. (similarity 0.80)
• Study 1 randomly assigned thousands of respondents to one, two, or three depolarization treatments. (similarity 0.79)

Broader Connections

• Depolarization interventions can succeed while creating unintended harms. #complicates (0.85)