Eliciting intelligence from sources informed about counter‐interrogation strategies: An experimental study on the Scharff technique

The Scharff technique aims to elicit information by affecting the source's perception of the interviewer's existing knowledge. Although the technique has been found to be effective for gathering new information, countermeasures to the technique have not been examined. In a 2 × 2 between‐subjects experiment, we informed half of the 120 sources about the counter‐interrogation strategy of carefully considering the interviewer's prior knowledge and the tactic of providing information perceived as already known to the interviewer. After this, sources were interviewed with the Scharff technique or the Direct approach, widely used in human intelligence‐gathering situations and consisting of open‐ended and direct questions. We found that “informed sources” did not succeed in revealing information already known to the interviewer, where informed sources and uninformed sources revealed known information to a similar degree (1.62 pieces vs. 1.65 pieces). Sources interviewed with the Direct approach (vs. Scharff technique) revealed a larger amount of information previously known to the interviewer (2.18 pieces vs. 1.08 pieces). When interviewed with the Scharff technique, sources informed about the counter‐interrogation strategy attempted to adopt more counter‐interrogation strategies. The present study replicates earlier research on the Scharff technique as a technique effective in affecting the source's perception of the interviewer's prior knowledge. The results of the current study indicate that both the Scharff technique and the Direct approach might be similarly robust against counter‐interrogation strategies, in terms of gathering new information. Future studies should focus on implementing more comprehensive training in counter‐interrogation strategies for the sources.