EV-0042
The best evidence in this library that training changes behavior
Morewedge, C. K., Yoon, H., Scopelliti, I., Symborski, C. W., Korris, J. H., & Kassam, K. S. (2015). Policy Insights from the Behavioral and Brain Sciences, 2(1), 129-140 · Source
What this entitles us to say
Two longitudinal experiments finding that a single training intervention - a video or an interactive game - produced large reductions in several cognitive biases, with effects still present two months later, and a later field study reporting the effects transfer outside the laboratory.
What it found
Two longitudinal experiments using a single training intervention - either an instructional video or an interactive game - targeting bias blind spot, confirmation bias, fundamental attribution error, anchoring, representativeness and social projection.
Effects were large (reported at Cohen's d > 1) and still present two months later. The game outperformed the video in both experiments. A 2019 follow-up published in Psychological Science reported that the training transferred to decisions in the field.
The authors note the contrast with the field's own history: earlier attempts to reduce decision biases through training had met with so little success that researchers had largely moved on to changing incentives and choice architecture instead.
Why it matters here
This entry does a job no other one in the library does. Every other file argues that a trait matters. This is the only evidence so far that structured teaching can move something in this territory and have it stick - which is the question a chief executive writing a cheque is actually asking.
It also carries three lessons for how the modules should be built:
1. The interactive version beat the passive one. The game outperformed the video, twice. That is a direct argument for the five-beat module's check and the workbook's written prompts over anything lecture-shaped. 2. A single session held for two months. It supports spacing modules across weeks rather than compressing them, and it supports the re-assessment at three and six months as a real measurement rather than a marketing moment. 3. Be careful with it. It is about thinking errors, not character. Stretching it into "research proves character training works" would be exactly the overclaim the Attitude and Discipline files were built to guard against.
The limits
This is about cognitive biases in decision-making, not about character traits - the transfer to honesty, courage or faithfulness is not demonstrated and must never be implied. It is a small number of experiments, not a meta-analysis. Note also the history the authors themselves record: earlier attempts at debiasing training largely failed, which is why this result was notable. Two months is a real follow-up but far short of the six-month program this material supports. Verified to abstract level.
What we do not say
"Research proves character training works." This is about cognitive bias in decision making. It is an encouraging analogy for our method, not evidence for our claims.