This study aims to evaluate the impact of a training course focused on investigative mindset and interview planning among police officers by analysing whether such training could mitigate confirmation bias and enhance the quality of suspect interview planning, including the formulation of investigative hypotheses, interview objectives, topics and questions.
Following a pre–post design, participants completed structured interview planning tasks before and after an 8-h training course. These tasks involved generating investigative hypotheses, defining interview objectives, identifying relevant topics and formulating questions. Responses were compared using non-parametric statistical tests to assess training effects.
Results showed that trained officers generated significantly more alternative hypotheses, planned more open-ended questions and demonstrated reduced reliance on closed-minded objectives and inappropriate questions. However, training effects on hypotheses generation were less pronounced in a case where the suspect’s guilt seemed more evident, suggesting that perceived strength of evidence can hinder hypotheses generation.
The findings support the inclusion of modules focused on planning and investigative mindset in police training programs. It also highlights the need for interventions that combine theoretical knowledge with practical, reflective learning.
This is the first empirical study to isolate and evaluate the effects of training focused specifically on investigative mindset and interview planning. It suggests that focused training can enhance interview planning quality, mitigate confirmation bias and foster more ethical and effective investigative practices.
