The Correct Response Negativity (CRN) is an event-related potential component that is affected by the act of deception. However, there have been inconsistent findings on the effect of deception on the CRN. Suchotzki, et al. (2015) suggested that the design of the paradigm used to elicit the deceptive response is what controls the size of the CRN. Specifically, motivation to deceive changes the size of deception relative to telling the truth. This study attempted to follow up on suggestions made by Suchotzki et al. (2015) to investigate if extraneous motivation to lie does indeed invert the ratio of CRN in lie compared to truth responses in a deception experiment by manipulating the motivation to lie. This study used a modification of the image-based guilty knowledge test (GKT) paradigm used in Langleben et al. (2002). The first hypothesis of this experiments was that a larger CRN during deception relative to truth-telling will be observed when participants are not motivated to lie, while a larger CRN during truth-telling relative to deception will be observed when participants are motivated to lie. The hypothesis was not supported. The second hypothesis of this experiment was that the P300 component would be larger when participants were motivated to lie, as compared to when they were instructed to lie. Results indicated that P300 was significantly higher in the lie conditions than in the truth conditions; however, there was no difference in amplitude as a function of whether they were in the informed or motivated lie condition.

This dissertation presents two individual-difference measures that could be used to assess the validity of eyewitness identification decisions. We designed a non-forced two-alternative face recognition task (consisting of mini-lineup test pairs, half of which included a studied face and half of which did not). In three studies involving a total of 583 subjects, proclivity to choose on pairs with two unstudied faces weakly predicted mistaken identifications on culprit-absent lineups, with varying correlation coefficients that failed to reach the value r = 0.4 found in Baldassari, Kantner, and Lindsay (under review). The likelihood of choosing correctly on pairs that included a studied face was only weakly predictive of correct identifications in culprit-present lineups (mean r of .2). We discuss ways of improving standardized measures of both proclivity to choose and likelihood to be correct when choosing. The second measure is based on the Guilty Knowledge Test (GKT), a lie detection method that utilizes an oddball paradigm to evoke the P300 component when a witness sees the culprit. This GKT-based lineup was intended to postdict identification accuracy regardless of witnesses’ overt responses, thus faces are used as stimuli. Half of participants were instructed to respond as if they knew the culprit and wanted to falsely exonerate him. P300 amplitudes evoked by the culprit were indistinguishable from those evoked by a different learned face but were larger than P3s evoked by unfamiliar faces in both the described lying condition and the group of participants who intentionally told the truth. / Graduate / 2018-12-05