Increasing the number of irrelevant stimuli increases ability to detect countermeasures to the <scp>P</scp>300‐based <scp>C</scp>omplex <scp>T</scp>rial <scp>P</scp>rotocol for concealed information detection

Based on P300 data, 100% of the simple guilty (no countermeasure use) and 92% of the innocent subjects were correctly identified as having or not having concealed information. In the countermeasure groups, detection rates varied from 71% to 92% across the different groups. Notably, in the present study with eight irrelevant items, simultaneous countermeasure use was indicated by elevated RT in the 50% and 75% countermeasure proportion groups, which it was not, previously, with 50% (two) countermeasures and four irrelevants.