Abstract
BackgroundIn criminal investigations, uncooperative witnesses might deny knowing a perpetrator, the location of a murder scene or knowledge of a weapon. We sought to identify markers of recognition in eye fixations and confidence judgments whilst participants told the truth and lied about recognising faces (Experiment 1) and scenes and objects (Experiment 2) that varied in familiarity. To detect recognition we calculated effect size differences in markers of recognition between familiar and unfamiliar items that varied in familiarity (personally familiar, newly learned).ResultsIn Experiment 1, recognition of personally familiar faces was reliably detected across multiple fixation markers (e.g. fewer fixations, fewer interest areas viewed, fewer return fixations) during honest and concealed recognition. In Experiment 2, recognition of personally familiar non-face items (scenes and objects) was detected solely by fewer fixations during honest and concealed recognition; differences in other fixation measures were not consistent. In both experiments, fewer fixations exposed concealed recognition of newly learned faces, scenes and objects, but the same pattern was not observed during honest recognition. Confidence ratings were higher for recognition of personally familiar faces than for unfamiliar faces.ConclusionsRobust memories of personally familiar faces were detected in patterns of fixations and confidence ratings, irrespective of task demands required to conceal recognition. Crucially, we demonstrate that newly learned faces should not be used as a proxy for real-world familiarity, and that conclusions should not be generalised across different types of familiarity or stimulus class.
Highlights
Concealed knowledge tests employed in field practice typically use autonomic measures such as skin conductance to detect crime details (Ben-Shakhar & Elaad, 2003; Gamer, 2011; Gamer, Verschuere, Crombez, & Vossel, 2008; Meijer, Klein Selle, Elber, & Ben-Shakhar, 2014)
Using fixations to detect recognition Emergent research suggests that recognition detection of personally familiar faces is robust, such that fixation patterns for personally familiar faces are distinguished from genuinely unfamiliar faces despite cognitive effort to conceal recognition during explicit denial (Millen et al, 2017) and informed strategies to beat the test
In an entirely novel strand of the research, we examine whether patterns of verbal confidence judgments differ for familiar and unfamiliar items and how these patterns change across stimulus class, familiarity and explicit denial of knowledge
Summary
Concealed knowledge tests employed in field practice typically use autonomic measures such as skin conductance to detect crime details (Ben-Shakhar & Elaad, 2003; Gamer, 2011; Gamer, Verschuere, Crombez, & Vossel, 2008; Meijer, Klein Selle, Elber, & Ben-Shakhar, 2014). Findings for less familiar faces (e.g. one brief exposure and famous celebrities) are smaller and less robust (Millen et al, 2017) These findings are in line with existing research indicating that exposure to variability in appearance and personal social and emotional experiences (i.e. personal familiarity) facilitates fast, reflexive recognition (Gobbini & Haxby, 2007; Natu & Toole, 2011; Wiese et al, 2019). Beyond faces, these findings are consistent with Peth et al (2013), who reported less robust findings for incidentally acquired knowledge of objects during a mock crime; items central to the crime were successfully detected, but those peripheral to it were not. To detect recognition we calculated effect size differences in markers of recognition between familiar and unfamiliar items that varied in familiarity (personally familiar, newly learned)
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