Extracting critical information from group members' partial knowledge using the searching concealed information test

The Concealed Information Test (CIT) is a psychophysiological method designed to detect information that an individual cannot or does not wish to reveal. The present study used a version of the CIT, the Searching Concealed Information Test (SCIT), to extract information from partial information that participants possessed on a planned jailbreak. In the first experiment, 52 undergraduate students were randomly, but not equally, allocated into 15 different clusters of partial knowledge. In each, participants possessed knowledge about 2 of 6 critical items. Using a lenient decision rule, and a combined measure defined as the mean of 3 individual measures (skin conductance response amplitude, finger pulse, and respiration line length) 5 of the 6 critical items were identified. Experiment 2 extended the first experiment to unequal proportions of critical knowledge. Forty-six undergraduate students were randomly allocated into 25 clusters of partial knowledge in which 0, 1, 2, 3, or 6 pieces of information were known. Using the same lenient decision rule and the combined measure, all 6 items were identified. It was suggested that the Group SCIT is capable of assembling a comprehensive picture out of partial information possessed by informed innocent participants.