Obtaining detailed accounts from individuals who have witnessed complex events under challenging encoding conditions presents a difficulty for investigators. In the present research, participants (N = 132) reported their recall of an event witnessed under full or divided attention using a timeline reporting format. Extending the Timeline Technique to assess the relative performance of two additional mnemonics, Self-Generated Cues (SGC) and Other-Generated Cues (OGC), participants provided an account across three Timeline reporting conditions comparing the efficacy of SGC, OGC, and No Cues (control). Mock-witnesses using SGC provided more correct details than mock-witnesses in the OGC or No Cues conditions, under full but not under divided attention conditions. There was no difference between cue conditions with respect to the number of errors reported across attention conditions. Findings show SGC to be a promising addition to interviewing techniques as a retrieval support mnemonic with implications for applied contexts.

Summary In information gathering interviews, follow‐up questions are asked to clarify and extend initial witness accounts. Across two experiments, we examined the efficacy of open‐ended questions following an account about a multi‐perpetrator event. In Experiment 1, 50 mock‐witnesses used the timeline technique or a free recall format to provide an initial account. Although follow‐up questions elicited new information (18–22% of the total output) across conditions, the response accuracy (60%) was significantly lower than that of the initial account (83%). In Experiment 2 (N = 60), half of the participants received pre‐questioning instructions to monitor accuracy when responding to follow‐up questions. New information was reported (21–22% of the total output) across conditions, but despite using pre‐questioning instructions, response accuracy (75%) was again lower than the spontaneously reported information (87.5%). Follow‐up open‐ended questions prompt additional reporting; however, practitioners should be cautious to corroborate the accuracy of new reported details.

In criminal investigations and human intelligence gathering contexts obtaining reliable information about the verbal content of criminal interactions (what was said and who said what) may be critical. We found that mock witnesses who used a selfadministered timeline format reported more information overall, more verbatim information, made fewer sequencing errors, and were more likely to correctly identify 'who said what' than those participants who used a free recall reporting format. These findings contribute to the work of practitioners in investigative and intelligence gathering contexts by facilitating the elicitation of detailed accounts, including conversational details.

Reports about repeated experiences tend to include more schematic information than information about specific instances. However, investigators in both forensic and intelligence settings typically seek specific over general information. We tested a multi-method interviewing format (MMIF) to facilitate recall and particularisation of repeated events through the use of the self-generated cues mnemonic, the timeline technique, and followup questions. Over separate sessions, 150 adult participants watched four scripted films depicting a series of meetings in which a terrorist group planned attacks and planted explosive devices. For half of our sample, the third witnessed event included two deviations (one new detail and one changed detail). A week later, participants provided their account using the MMIF, the timeline technique with self-generated cues, or a free recall format followed by open-ended questions. As expected, more information was reported overall in the MMIF condition compared to the other format conditions, for two types of details, correct details, and correct gist details. The reporting of internal intrusions was comparable across format conditions. Contrary to hypotheses, the presence of deviations did not benefit recall or source monitoring. Our findings have implications for information elicitation in applied settings and for future research on adults' retrieval of repeated events.

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