The mechanism of filler items in the response time concealed information test

Ulrich Ansorge,Gáspár Lukács

doi:10.1007/s00426-020-01432-y

Ulrich Ansorge, Gáspár Lukács

Open Access

https://doi.org/10.1007/s00426-020-01432-y

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Abstract

The response time concealed information test (RT-CIT) can reveal that a person recognizes a relevant (probe) item among other, irrelevant items, based on slower responding to the probe compared to the irrelevant items. Therefore, if this person is concealing the knowledge about the relevance of this item (e.g., recognizing it as a murder weapon), this deception can be unveiled. Adding familiarity-related filler items to the task has been shown to substantially increase the validity of the method, but assumptions for this effect have never been tested before. In the present series of three experiments (N = 511), we tested several factors, most of which were found to indeed influence the enhancing effects of fillers. First, larger enhancement is achieved when a smaller proportion of fillers shares the response key with the target. Second, familiarity context does play a role in the enhancement, and the target sharing its response key with the familiarity-referring fillers leads to larger enhancement. Third, mere symbolic fillers (such as simple arrow-like characters) also lead to enhancement, but filler words without task-relevant meaning are not effective. Fourth, small visual differences (lettercase or underlining) between fillers and the rest of the items have no significant influence. All this provides justification for the original structure of the fillers and also demonstrates that the enhancement is highly generalizable: Fillers have a potential to improve the RT-CIT regardless of deception scenario, item types, or the examinee's language comprehension.

Highlights

Undetected deception may lead to extreme costs in certain scenarios such as counterterrorism, pre-employment screening for intelligence agencies, or high-stakes criminal proceedings
The concealed information test (CIT) aims to disclose whether examinees recognize certain relevant items, such as a weapon used in a recent homicide, among a set of other objects, when they try to conceal any knowledge about the criminal case
The present study aims to test the key hypotheses, as well as some potentially relevant underlying factors, and, thereby, gain insight into the mechanism of filler items in the response time concealed information test (RT-CIT)

Summary

Introduction

Undetected deception may lead to extreme costs in certain scenarios such as counterterrorism, pre-employment screening for intelligence agencies, or high-stakes criminal proceedings. Researchers have advocated special techniques that facilitate lie detection, including computerized tasks such as the concealed information test (CIT; Lykken, 1959; Meijer, Selle, Elber, & Ben-Shakhar, 2014). The CIT aims to disclose whether examinees recognize certain relevant items, such as a weapon used in a recent homicide, among a set of other objects, when they try to conceal any knowledge about the criminal case. In the response time (RT)-based CIT, participants classify the presented stimuli as the target or as one of several nontargets by pressing one of two keys (Seymour, Seifert, Shafto, & Mosmann, 2000; Suchotzki, Verschuere, Van Bockstaele, Ben-Shakhar, & Crombez 2017; Varga, Visu-Petra, Miclea, & Buş, 2014). The items are repeatedly shown in a random sequence, and all of them have to be responded to with the same response keys, except one arbitrary target—a randomly selected, originally irrelevant

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