Can Jurors Disregard Inadmissible Evidence? Using the Multiphase Optimization Strategy to Test Interventions Derived...

Area of Science:

• Legal Psychology
• Cognitive Psychology
• Jury Decision-Making

Background:

• Inadmissible evidence often biases jurors towards guilty verdicts, compromising fair trials.
• Judicial instructions to disregard such evidence are standard but often ineffective.
• Existing research indicates jurors struggle to ignore inadmissible information even when instructed.

Purpose of the Study:

• To test four theory-driven strategies to help jurors disregard inadmissible evidence.
• To identify an optimized intervention package for juror comprehension.
• To evaluate the effectiveness of this package against standard judicial instructions.

Main Methods:

• Study 1: A 2^4 full factorial randomized controlled trial assessed four candidate intervention strategies.
• Study 2: A parallel four-arm randomized controlled trial compared conviction rates across four conditions.
• Conditions included: no inadmissible evidence, inadmissible evidence without objection, standard judicial instructions, and instructions plus the optimized intervention.

Main Results:

• A synergistic interaction among the four candidate strategies identified an optimized intervention package.
• Mock jurors receiving the optimized intervention package showed significantly lower conviction rates.
• The optimized intervention package proved more effective than judicial instructions alone.

Conclusions:

• Novel intervention strategies show promise in aiding jurors to disregard inadmissible evidence.
• The optimized intervention package offers a potentially more effective safeguard for defendants' rights.
• Further research and implementation of these strategies are warranted to improve jury decision-making.