8 files

Dataset for research paper ‘Unanticipated questions can yield unanticipated outcomes in investigative interviews’

posted on 12.10.2018 by Thomas Parkhouse, Thomas Ormerod
Data files for the paper submitted to PLOSOne

A copy of SPSS software is required to open these .sav files.

-Experiment 1 Interviewer Accuracy (dichotomous choice RM): this shows the number of times each interviewer correctly guessed the veracity of the interviewee for each of the six conditions. A repeated measures ANOVA was conducted on this data.
-Experiment 1 Interviewer Compliance: this shows the number of deviations from script made by interviewers for each interview.
-Experiment 1 Interviewer Reasons: this show the number of reasons interviewers gave for their veracity decisions, coded into 4 categories. A binary logisitic regression was used on this data, with accuracy as the outcome variable.
-Experiment 1 interviewer accuracy (scale judgement): this shows the interviewer veracity scale scores, with liars' scores reversed. This was analysed with a between-groups ANOVA.
-Experiment 1 Manipulations & Anticipation: this includes the data on Question Anticipation and Question Difficulty.
-Experiment 1 Reality Monitoring: this data shows the % of word count for each interview that fell within the 4 reality monitoring categories. A MANOVA was conducted on this data.
-Experiment 2 Observer Accuracy (dichotomous choice): this data show the accuracy of forced choice decision for observers accros each condition. This was analysed with a series of one-sample t-tests.
-Experiment 2 Observer Accuracy (Scale; with liars scores Reversed): this data shows the Observer Veracity Scale Ratings. This was analysed with a repeated measures ANOVA.

Abstract for research paper
Asking unanticipated questions in investigative interviews can elicit differences in the verbal behaviour of truth-tellers and liars: When faced with unanticipated questions, liars give less detailed and consistent responses than truth-tellers. Do such differences in verbal behaviour lead to an improvement in the accuracy of interviewers’ veracity judgements? Two empirical studies evaluated the efficacy of the unanticipated questions technique. Experiment 1 compared two types of unanticipated questions, assessing the veracity judgements of interviewers and verbal content of interviewees’ responses.. Experiment 2 assessed veracity judgements of independent observers. Overall, the results provide little support for the technique. For interviewers, unanticipated questions failed to improve veracity judgement accuracy above chance. Reality monitoring analysis revealed qualitatively distinct information in the responses to the two unanticipated question types, though little distinction between the responses of truth-tellers and liars. Accuracy for observers was greater when judging transcripts of unanticipated questions, and this effect was stronger for spatial and temporal questions than planning questions. The benefits of unanticipated questioning appear limited to post-interview situations. Furthermore, the type of unanticipated question affects both the type of information gathered and the ability to detect deceit.


The project was funded by The Engineering and Physical Sciences Research Council (grant number: EP/M508172/1).




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