Prolonged Response Time Concealed Information Test Decreases Probe-Control Differences but Increases Classification Accuracy

The Response Time Concealed Information Test (RT-CIT) can reveal that a person recognizes a relevant item (probe, e.g., a murder weapon) among other irrelevant items (controls), based on slower responses to the probe compared to the controls. The present paper assesses the influence of test length (due to practice, habituation, or fatigue) on two key variables in the RT-CIT: (a) probe-control differences and (b) classification accuracy, through a meta-analysis (using 12 previous experiments), as well as with two new experiments. It is consistently demonstrated that increased test length decreases probe-control differences but increases classification accuracies. The main implication for real-life application is that using altogether at least around 600 trials is optimal for the RT-CIT.