Publications Pages Publications Pages. Search my Subject Specializations: Select Users without a subscription are not able to see the full content. More This book reveals the secret to detecting artifacts items. Authors Affiliations are at time of print publication. Joe Nickell, author More Less. Print Save Cite Email Share. Show Summary Details.
Subscriber Login Email Address. Library Card. View: no detail some detail full detail. Chapter 1 Investigating Documents. Chapter 2 Diary of Jack the Ripper. Chapter 3 Novel by an American Slave. Chapter 6 Out of the Archives. Chapter 9 Likenesses of Lincoln. Chapter 10 Assassin or Look-Alike. Chapter 11 From the Album. Chapter 12 Authenticating Artworks and other Artifacts.
Chapter 13 Lost Icon Found. Chapter 15 Debris from the Titanic. The tendency to deploy strategic fixation improved with experience, suggesting that authentication benefits from precise visual orienting and refined categorisation criteria. Authentication is a cognitive process used to detect close mimics of motivationally salient objects so that unnecessary or costly effort in approaching or avoiding them can be prevented. Indeed, judging the authenticity of many objects is a critical component of food plant or prey and predator identification for most animal species 1. For humans in the digital age where full-colour, high resolution graphic reproduction is ubiquitous, judging authenticity is important for approaching or avoiding stimuli used for socially and economically significant transactions or permissions.
Specifically, authentication of complex, valuable documents e. Yet, the cognitive processes that underpin visual authentication in humans remain poorly understood. To investigate, we examined visual authentication of banknotes, focusing specifically on the visual foraging strategies used for these highly familiar and frequently-handled stimuli.
Although billions of people exchange banknotes every day, how these valuable objects are visually examined during authentication has not previously been reported. Judging whether a banknote or other object is authentic is distinct from tasks involving rapid detection of a pre-defined target, as in widely-studied visual search tasks used in cognitive psychology laboratories.
Typically, in those studies, the presence of a single visual target with pre-defined features must be detected in an array of other simultaneously presented objects or within a complex scene 6 , 7 , 8. The categories defining target versus distractors or background scene elements are usually distinct and widely separated in at least one and often many dimensions.
Eye movements during such tasks tend to be rapidly directed toward only those scene areas containing targets or target-like features 9 , 10 showing that a priori knowledge of the search goal contributes to mechanisms controlling eye movements. In contrast, in an authentication task, the critical sensory information, or tell, used to confirm a counterfeit versus genuine decision is typically unspecified.
A counterfeit tell can be the absence of an expected sensory detail, or the presence of an unexpected specific detail or feature.
Identity Verification and Validation
The tell or tells are necessarily imbedded within the object being authenticated. This means that the observer must judge object authenticity whilst processing a range of other object-related sensory signals that are highly consistent with internally generated neural predictions about the object derived from previous encounters with genuine exemplars As banknote counterfeit are rare in many communities, prior experience of how a counterfeit might differ in appearance from a genuine note is lacking for many banknote users.
Moreover, counterfeits vary in their accuracy of mimicry, meaning that having identified a counterfeit tell previously might not facilitate detection of a subsequently encountered counterfeit. However, some people have some explicit knowledge of how to check a banknote e.
Banknote authentication by the general public is also unlike well-studied medical diagnostic and baggage security screening tasks that involve extensive training of observers 13 , 14 , 15 , 16 , In both these highly-skilled tasks, rare visual targets that could belong to multiple, loosely defined categories must be discovered within complex scenes.
Previous studies linking performance and eye movements in these tasks have shown that the acquisition of both explicit knowledge of targets and the accumulation of considerable visual experience with them leads to more efficient and target-directed eye movements, as well as better performance 15 , These studies not only support the notion that eye movements are instrumental for performance on these tasks, they also underscore the point that experience controls oculomotor orienting in context-specific ways.
In the case of banknote authentication, the general public have little or no experience with counterfeit and limited explicit knowledge of what the visual tell s identifying a note as counterfeit might look like In the absence of such information, how are eye movements controlled and can they reveal the state of knowledge held by users? We reasoned that, with no a priori knowledge, a useful eye movement strategy for authenticating banknotes might be to distribute fixations across the whole surface of the banknote without regard to content, searching for any discrepancy between the observed and a remembered genuine note.
Such a search could be potentially exhaustive, defaulting to acceptance of the note as genuine only after a thorough search revealed no discrepancy. However, such a strategy would be reliant on a detailed and accurate memory of the genuine object. Considering previous findings of surprisingly poor explicit memory of details on everyday objects, like banknotes 18 , a widely distributed search strategy might be associated with poor authentication performance.
Alternatively, users could be more strategic in their visual foraging of banknotes if they were equipped with specific knowledge about the presence and location of specially-printed, harder to mimic elements, known as security features e. The visual characteristics of banknote security features are intended to provide obvious authenticity tells to users whilst at the same time being particularly difficult to reproduce using commercially available technologies. Such directed fixations should be especially helpful considering that the critical authentication tell inherent in most security features is physically small and detailed, requiring precise fixation to be properly evaluated.
However, it remains unknown whether security features are fixated more than other areas on banknotes because, to our knowledge, no previous study of eye movements during banknote authentication has been published.
Real or Fake: Studies in Authentication
Nevertheless, security features that provide ostensibly obvious cues to authenticity are widely used as counterfeit deterrents for banknotes, passports, and other high value government-issued documents. Although they add considerably to document costs and thus burden the tax-payer, evidence that security features are used by the public has thus far been based solely on interview and questionnaire data Although it is well established that high-level cognitive mechanisms coding current goals and prior knowledge 19 , 20 are able to control eye movements, there is also substantial evidence that gaze can be automatically captured by sensory configurations within a scene.
If gaze during banknote authentication were captured in this way by a specific sensory feature, e. In contrast, tendencies to strategically fixate useful, hard to mimic areas, such as a security feature, should be predictive of authentication performance and also become more pronounced with experience. To investigate, we monitored eye movements of adults recruited from the general public as they authenticated as quickly as possible a series of genuine paper banknotes not digitised images interspersed with two counterfeit notes.
Genuine notes used here were in general circulation at the time of the study; counterfeits were forensically recovered items; and both banknote types had similar signs of wear. To assess gaze prioritization in this task and how it was affected by experience, we assessed the distribution of fixations whilst participants authenticated successive presentations of genuine notes before and then again after encountering counterfeit. We compared the proportion of fixations directed at each of four different areas of interest AOIs on the banknote see Fig.
To distinguish the latter two possibilities, we examined effects of experience and correlated fixation probabilities with authentication performance. Such analyses were also used to assess how instrumental eye movements are for authentication. The solid lines not visible to the participant demarcate areas of interest AOI used to classify fixations.
Bar colours represent note conditions as in B. Touching the note was not permitted. Unbeknownst to the participant the series was not random, but rather comprised a succession of 20 genuine notes, a single counterfeit, another 13 genuine notes, and, lastly, another counterfeit. This series created three note conditions: pre-counterfeit genuine, post-counterfeit genuine, and counterfeit first and second notes. Both counterfeit notes were correctly rejected by The two counterfeits, although slightly different from one another, were rejected equally often Participants were On average, genuine notes were rejected on First, the distribution of fixations across the note during the entire viewing interval without regard to fixation order was analysed.
This whole-interval analysis was used to indicate what information was acquired prior to decision-making. Second, the sequence of fixations scan patterns used when initially viewing the note was examined so that orienting prioritization could be investigated. For both sets of analyses, we compared eye movement behaviours before and after counterfeit exposure to assess effect of this experience. First, genuine notes were sometimes reported as counterfeit, meaning that correct detection of the counterfeit could be unrelated to awareness of its tell s. Second, misclassifying the counterfeit cannot be used to infer lack of awareness of the counterfeit tell s because awareness could have emerged retrospectively upon viewing the next genuine note.
For whole interval analysis, the proportion of fixations directed at each AOI was determined for each note condition and participant. Group means are shown in Fig.
Fixation proportions were analysed by conducting repeated measures analyses of variance ANOVA separately for each AOI using note type as a within-subjects factor. These findings suggest that neither experience pre versus post counterfeit nor small sensory differences between genuine and counterfeit contributed to choices over what information to check prior to submitting an authentication decision.
See Fig. Tendency to fixate the Portrait or Watermark area was non-predictive of performance.
However, propensity to fixate the Hologram AOI was found to be highly predictive of counterfeit sensitivity; propensity to avoid the Number AOI was also predictive, albeit less reliably. To determine if a combination of these latter two behaviours supported good authentication even before a counterfeit had been encountered , the probability of fixating the Hologram AOI minus the probability of fixating the Number AOI was calculated for each participant for the pre-counterfeit genuine note condition.
As can be seen in Fig. We also analysed the average duration dwell of fixations directed at each AOI during the whole viewing interval. This effect resulted from note type determining the average dwell for the Hologram AOI. No significant note condition effects were found for any other AOI.
Longer mean dwell on the counterfeited versus genuine Hologram AOI is consistent with previous studies of eye movements during reading that showed prolonged dwell on words offering greater cognitive challenge e. Thus, the current observation of extended dwell to the counterfeit Hologram AOI suggests that the anomalous security feature found there initiated greater cognitive processing.
Real or Fake: Studies in Authentication - Joe Nickell - Google Libros
On average, participants made 8. To investigate visual orienting prioritization, we next analysed scan patterns, i. The proportion of fixations directed at each AOI for each of the first six fixations are plotted in Fig. We conducted repeated measures ANOVAs separately for each AOI that used serial fixation order 1—4 and note condition pre-counterfeit, post counterfeit as within-subject factors. The group mean proportion of fixations allocated to each AOI. However, this effect did not depend on note type [ F 2. However, the proportion of fixations it attracted dropped significantly from a group average of 0.
Taken together these results not only argue against the idea that scanning banknotes is independent of content, they indicate that experience serves to modulate orienting prioritisation.
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Although the first and third fixations were most likely to be captured by the Portrait and Hologram AOIs, respectively, for both note conditions, the second fixation was more likely to be captured by the Portrait in the pre-counterfeit condition and by the Hologram in the post-counterfeit condition. This general pattern suggests that with experience, participants learned to suppress capture by the portrait, prioritise fixation of the Hologram area, and suppress fixation of the Number AOI.
The latter area is probably habitually fixated in normal cash transactions where banknote denomination is important, whereas in the task used here, such information was irrelevant and fixation of this AOI unhelpful. As there were only two counterfeit notes tested in this study, data for analysis of sequential fixations of these notes were thin.
Even so, we observed very similar scan patterns for counterfeits as for genuine notes. The aim of this study was to determine how eye movements are used to visually forage for information when authenticating a complex object.