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

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.

Prolonged response time concealed information test decreases probe-control differences but increases classification accuracy.

“…Nontarget-side fillers are control-referring expressions (e.g., the words “unfamiliar” or “irrelevant”) and have to be categorized with the same key as the probe and the controls. Fillers do not serve any diagnostic purpose, but their inclusion increases probe-control differences, thereby also increasing diagnostic efficiency based on these differences (for details, see Lukács & Ansorge, 2021; Lukács et al, 2017).…”

“…Furthermore, from another perspective, a series of studies shows that more cognitively demanding RT-CIT designs (e.g., increased number of different items in the task) increase probe-control differences (Hu et al, 2013; Lukács & Ansorge, 2021; Verschuere et al, 2015; Visu-Petra et al, 2013). This could also imply that if participants can perform the task more easily after practicing it for some time, the decreased cognitive demand may lead to decreased probe-control differences.…”

“…However, certain RT-based deception detection tests with "truth" versus "lie" (or "control") responses have also shown tendencies of diminished truth-lie effects with practice-although these findings are mixed and probably to a great extent depend on specific task designs and paradigms (Hu et al, 2012;Johnson et al, 2005;Van Bockstaele et al, 2012;Vendemia et al, 2005). In the RT-CIT specifically, slower responding to probes as compared to controls are generally assumed to originate in the perception of probes as response-incompatible stimuli (e.g., Lukács & Ansorge, 2021;Seymour & Schumacher, 2009;Verschuere & De Houwer, 2011). 2 Therefore, it is suggestive that various classic psychological RT tests that involve incompatible stimuli, to which comparatively slow responses are made, have also repeatedly been shown to be affected by practice, with RT differences between compatible and incompatible stimuli 3 decreasing with larger numbers of trials (e.g., Chen et al, 2013;D'Ascenzo et al, 2021;Gillebaart et al, 2020;Stroop, 1935).…”

Importance‐related fillers improve the classification accuracy of the response time concealed information test in a crime scenario

“…The results of the Lukács, Kleinberg, et al (2017) study confirmed this reasoning. Also, a follow-up study (Lukács & Ansorge, 2021) provided strong evidence that the meaning of the fillers matters: reversing key mapping (unfamiliarity-related fillers categorized together with targets), as well as using neutral (e.g., object name) or pseudoword fillers, both reduced, or even obliterated, the enhancing effect of fillers.…”

“…Furthermore, during the main task there was no header in either of our protocols.6 The smaller proportion (three to six) of important relative to unimportant fillers is intended to keep 'target-side' items (i.e. the target and items to be categorized with the same key as the target) less frequent than the rest of the items, thereby keeping the target (or all target-side items) more rare or even unique among all used items, since this relative rarity is assumed to contribute to the response conflict in case of probes: For more detailed explanation and empirical evidence, seeLukács & Ansorge (2021).…”