Figure 1
An example of two counter-balanced stimuli for the Questioned Signature Position format as they were displayed on the eye-tracking system. These stimuli differ only in the position of the questioned and known signatures. The order of the known signatures did not vary, so that in the left example known signatures 1, 3, and 5 were adjacent to the questioned signature. In the example on the right, signatures 2, 4, and 6 were adjacent to the questioned signature.
Figure 2
An example of two counterbalanced Protocol 2 stimuli as they were displayed on the eye-tracking system. These stimuli differ in the order of presentation of the questioned and known signatures. In the top example the questioned signature was presented alone, followed by the questioned signature paired with the known signatures. In the counterbalanced example at the bottom, the known signatures were presented first, followed by the questioned/known pairing. The order of the known signatures did not vary.
Figure 3
These images demonstrate different ways of visualizing eye-tracking data. The gaze plots at the left provide several kinds of information. Each circle represents a “fixation” where the participant’s gaze fell remained within a 50-pixel area for a time of greater than 100 msec. The size of the circle indicates “fixation duration,” or how much time in total the participant spent in that area. Larger circles indicate that the participant fixated in that area a greater amount time. The lines represent “saccades,” which are recordings of the movement of the eyes as they travel from one fixation to another. Thus, the gaze plot shows what the participant looked at, how long they looked at it, and the order in which the fixations occurred. The heat map displayed in the center image is a visualization of gaze concentration. Red and yellow areas indicate where the participant’s gaze was more concentrated. These areas correspond to the areas in the gaze plot where many fixations were recorded. The image on the right demonstrates how “areas of interest” (AOIs) were developed from the gaze plot and heat map visualizations. AOIs permit analysis of specific areas within an image.
Figure 4
The eye-tracking computer, pictured at the right, rests on an adjustable laptop stand. The experimenter controlled all activities and recorded all verbal responses by keyboard and mouse from the operator station, pictured on the left. This ensured that the participant’s gaze remained on the eye-tracker screen during the gaze recording sessions.
Figure 5
The Tobii X2-60® eye-tracker is located at the bottom of the computer display. The system projects infrared light into the participant’s eyes, illuminating the retina. The eye-tracking software records the position of the illuminated retina for each eye as X/Y coordinates. The raw data for the gaze position coordinates are then processed by the Tobii Pro Studio© software using the ClearView Fixation filter, which designates as a fixation any eye movement slowing below a velocity threshold of 50 pixels/100ms. During calibration, the eye- tracker records the position of the participant’s gaze as the participant visually follows the movement of a red spot as it travels randomly to each of the nine positions on the calibration grid displayed at the right.
Table 1
Known Signature Fixation Count by Ground Truth and Decision Accuracy.
| Known Signature Fixation Count and Ground Truth | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 95% Confidence Interval | |||||||||
| Ground Truth | N | M | SD | t | df | p | Lower CI | Upper CI | |
| FC Known 1 | Genuine | 763 | 17.68 | 25.58 | 9.36 | 962 | < .001 | 7.28 | 11.15 |
| Simulated | 935 | 8.47 | 10.28 | ||||||
| FC Known 2 | Genuine | 763 | 16.12 | 20.43 | 9.37 | 1032 | < .001 | 5.95 | 9.10 |
| Simulated | 935 | 8.59 | 9.57 | ||||||
| FC Known 3 | Genuine | 763 | 18.84 | 23.18 | 9.71 | 1145 | < .001 | 7.29 | 10.99 |
| Simulated | 935 | 9.70 | 13.06 | ||||||
| FC Known 4 | Genuine | 763 | 15.75 | 19.03 | 10.84 | 1026 | < .001 | 6.63 | 9.56 |
| Simulated | 935 | 7.66 | 8.81 | ||||||
| FC Known 5 | Genuine | 763 | 12.14 | 17.60 | 9.00 | 1059 | < .001 | 4.91 | 7.65 |
| Simulated | 935 | 5.86 | 8.66 | ||||||
| FC Known 6 | Genuine | 763 | 11.06 | 14.14 | 9.60 | 1118 | < .001 | 4.35 | 6.59 |
| Simulated | 935 | 5.59 | 7.66 | ||||||
| Known Signature Fixation Count and Decision Accuracy | |||||||||
| 95% Confidence Interval | |||||||||
| Decision Accuracy | N | M | SD | t | df | p | Lower CI | Upper CI | |
| FC Known 1 | Accurate | 1493 | 11.92 | 17.31 | -2.69 | 223 | .008 | -9.90 | –1.53 |
| Misleading | 205 | 17.63 | 29.72 | ||||||
| FC Known 2 | Accurate | 1493 | 11.39 | 14.79 | -3.07 | 230 | .002 | -7.91 | -1.73 |
| Misleading | 205 | 16.21 | 21.80 | ||||||
| FC Known 3 | Accurate | 1493 | 13.28 | 18.29 | -2.67 | 243 | .008 | -7.55 | -1.14 |
| Misleading | 205 | 17.63 | 22.31 | ||||||
| FC Known 4 | Accurate | 1493 | 10.77 | 14.19 | -3.19 | 237 | .002 | - 7.04 | -1.67 |
| Misleading | 205 | 15.12 | 18.81 | ||||||
| FC Known 5 | Accurate | 1493 | 8.22 | 12.51 | -2.57 | 225 | .011 | -6.70 | -0.89 |
| Misleading | 205 | 12.02 | 20.61 | ||||||
| FC Known 6 | Accurate | 1493 | 7.78 | 10.92 | -2.15 | 238 | .032 | -4.24 | -0.19 |
| Misleading | 205 | 9.99 | 14.17 | ||||||
Figure 6
Mean fixation counts for the Ground Truth analyses are presented at the left. Mean fixation counts for Decision Accuracy analyses are presented at the right. Fixation counts in the Ground Truth analyses were significantly greater for genuine than for simulated signatures. Fixation counts were significantly greater for misleading opinions than for accurate decisions. The three highest mean fixation counts for genuine and simulated signatures are indicated by the arrows. This demonstrates that FDEs utilized known signatures 1, 2, and 3 to a greater extent overall than they did known signatures 4, 5, and 6. The same pattern is revealed in the known signature fixation counts in the Decision Accuracy analyses.
Table 2
Regression Coefficients for Predictors of Ground Truth and Decision Accuracy.
| Ground Truth | |||||||
|---|---|---|---|---|---|---|---|
| 95% Confidence Interval | |||||||
| Areas of Interest All Knowns | B | Wald | df | p | Odds | Lower CI | Upper CI |
| FC Known 1 (center left) | -0.02 | 5.25 | 1 | .022 | 0.98 | 0.97 | 1.00 |
| FC Known 2 (center right) | 0.00 | 0.03 | 1 | .864 | 1.00 | 0.98 | 1.01 |
| FC Known 3 (top left) | 0.00 | 0.20 | 1 | .655 | 1.00 | 0.99 | 1.01 |
| FC Known 4 (top right) | -0.03 | 17.76 | 1 | <.001 | 0.97 | 0.95 | 0.98 |
| FC Known 5 (bottom left) | 0.00 | 0.13 | 1 | .723 | 1.00 | 0.99 | 1.02 |
| FC Known 6 (bottom right) | -0.01 | 0.67 | 1 | 0.413 | 0.99 | 0.97 | 1.01 |
| Decision Accuracy | |||||||
| 95% Confidence Interval | |||||||
| Areas of Interest All Knowns | B | Wald | df | p | Odds | Lower CI | Upper CI |
| FC Known 1 (center left) | 0.00 | 0.35 | 1 | .553 | 1.00 | 0.99 | 1.02 |
| FC Known 2 (center right) | 0.01 | 2.28 | 1 | .131 | 1.01 | 1.00 | 1.03 |
| FC Known 3 (top left) | -0.01 | 0.64 | 1 | .423 | 0.99 | 0.98 | 1.01 |
| FC Known 4 (top right) | 0.01 | 1.35 | 1 | .245 | 1.01 | 0.99 | 1.03 |
| FC Known 5 (bottom left) | 0.01 | 1.31 | 1 | .252 | 1.01 | 0.99 | 1.03 |
| FC Known 6 (bottom right) | -0.02 | 3.15 | 1 | .076 | 0.98 | 0.95 | 1.00 |
Table 3
Known Signature Fixation Count by Signature Type and Signature Complexity.
| Known Signature Fixation Count by Signature Type | ||||||||
|---|---|---|---|---|---|---|---|---|
| 95% Confidence Interval | ||||||||
| Area of Interest | Type | N | SD | t | df | p | Lower CI | Upper CI |
| FC Known 1 | Text | 934 | 22.09 | 4.08 | 1643 | < .001 | 1.91 | 5.46 |
| Stylized | 764 | 15.01 | ||||||
| FC Known 2 | Text | 934 | 17.81 | 4.22 | 1672 | < .001 | 1.68 | 4.61 |
| Stylized | 764 | 12.90 | ||||||
| FC Known 3 | Text | 934 | 21.03 | 3.68 | 1682 | < .001 | 1.53 | 5.03 |
| Stylized | 764 | 15.65 | ||||||
| FC Known 4 | Text | 934 | 17.07 | 5.21 | 1632 | < .001 | 2.25 | 4.97 |
| Stylized | 764 | 11.37 | ||||||
| FC Known 5 | Text | 934 | 16.40 | 5.01 | 1532 | < .001 | 1.94 | 4.43 |
| Stylized | 764 | 9.41 | ||||||
| FC Known 6 | Text | 934 | 12.90 | 4.93 | 1655 | < .001 | 1.58 | 3.67 |
| Stylized | 764 | 8.97 | ||||||
| Known Signature Fixation Count by Signature Complexity | ||||||||
| 95% Confidence Interval | ||||||||
| Area of Interest | Complexity | N | SD | t | df | p | Lower CI | Upper CI |
| FC Known 1 | High | 849 | 18.62 | –1.54 | 1688 | .123 | -3.28 | 0.39 |
| Low | 849 | 19.96 | ||||||
| FC Known 2 | High | 849 | 16.37 | -0.83 | 1696 | .409 | -2.15 | 0.88 |
| Low | 849 | 15.35 | ||||||
| FC Known 3 | High | 849 | 20.14 | -1.08 | 1696 | .282 | -2.78 | 0.81 |
| Low | 849 | 17.49 | ||||||
| FC Known 4 | High | 849 | 16.22 | -0.30 | 1639 | .766 | -1.63 | 1.20 |
| Low | 849 | 13.43 | ||||||
| FC Known 5 | High | 849 | 14.67 | -0.20 | 1667 | .841 | - 1.45 | 1.18 |
| Low | 849 | 12.86 | ||||||
| FC Known 6 | High | 849 | 12.32 | -0.09 | 1647 | .929 | -1.13 | 1.03 |
| Low | 849 | 10.35 | ||||||
Figure 7
Mean fixation counts for the Signature Type analyses are presented at the left. Mean fixation counts for Signature Complexity analyses are presented at the right. Fixation counts in the Signature Type analyses were significantly greater for text-based than for stylized signatures. Fixation counts were not significantly greater for low complexity than for high complexity signatures. The two highest mean fixation counts for text- based and for stylized signatures are indicated by the arrows. This demonstrates that FDEs utilized known signatures 1 and 3 to a greater extent than the other knowns in both the text-based and the stylized signatures. Similarly, at the right, the two highest mean fixation counts for high and low complexity signatures, known signatures 1 and 3, are indicated by the arrows, although these differences were not statistically significant.
Table 4
Regression Coefficients for Predictors of Signature Type and Signature Complexity.
| Signature Type | 95% Confidence Interval | ||||||
|---|---|---|---|---|---|---|---|
| Areas of Interest All Knowns | B | Wald | df | P | Odds | Lower CI | Upper CI |
| FC Known 1 (center left) | 0.00 | 0.02 | 1 | .893 | 1.00 | 0.99 | 1.01 |
| FC Known 2 (center right) | 0.01 | 0.84 | 1 | .360 | 1.01 | 0.99 | 1.02 |
| FC Known 3 (top left) | 0.01 | 1.48 | 1 | .225 | 1.01 | 1.00 | 1.02 |
| FC Known 4 (top right) | -0.02 | 6.35 | 1 | .012 | 0.98 | 0.97 | 1.00 |
| FC Known 5 (bottom left) | -0.01 | 2.66 | 1 | .103 | 0.99 | 0.97 | 1.00 |
| FC Known 6 (bottom right) | -0.01 | 0.81 | 1 | .368 | 0.99 | 0.97 | 1.01 |
| Signature Complexity | 95% Confidence Interval | ||||||
| Areas of Interest All Knowns | B | Wald | df | P | Odds | Lower CI | Upper CI |
| FC Known 1 (center left) | 0.01 | 3.78 | 1 | .052 | 1.01 | 1.00 | 1.02 |
| FC Known 2 (center right) | 0.01 | 0.65 | 1 | .419 | 1.01 | 0.99 | 1.02 |
| FC Known 3 (top left) | 0.00 | 0.24 | 1 | .624 | 1.00 | 0.99 | 1.01 |
| FC Known 4 (top right) | -0.01 | 0.96 | 1 | .328 | 0.99 | 0.98 | 1.01 |
| FC Known 5 (bottom left) | -0.01 | 1.97 | 1 | .161 | 0.99 | 0.97 | 1.00 |
| FC Known 6 (bottom right) | -0.01 | 0.44 | 1 | .509 | 0.99 | 0.98 | 1.01 |
Table 5
Known Signature Fixation Count by Signature Presentation Sequence and Questioned Signature Position.
| Known Signature Fixation Count and Signature Presentation Sequence | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 95% Confidence Interval | |||||||||
| Sequence | N | M | SD | t | df | P | Lower CI | Upper CI | |
| FC Known 1 | Questioned First | 849 | 16.22 | 22.84 | 7.83 | 1412 | < .001 | 5.41 | 9.02 |
| Known First | 849 | 9.00 | 14.09 | ||||||
| FC Known 2 | Questioned First | 849 | 14.82 | 17.98 | 7.52 | 1533 | < .001 | 4.21 | 7.18 |
| Known First | 849 | 9.13 | 12.82 | ||||||
| FC Known 3 | Questioned First | 849 | 17.29 | 21.40 | 7.74 | 1528 | < .001 | 5.21 | 8.74 |
| Known First | 849 | 10.32 | 15.16 | ||||||
| FC Known 4 | Questioned First | 849 | 14.55 | 17.67 | 9.24 | 1380 | < .001 | 5.13 | 7.90 |
| Known First | 849 | 8.04 | 10.49 | ||||||
| FC Known 5 | Questioned First | 849 | 11.39 | 16.82 | 8.25 | 1306 | < .001 | 4.13 | 6.71 |
| Known First | 849 | 5.97 | 9.11 | ||||||
| FC Known 6 | Questioned First | 849 | 10.33 | 13.35 | 8.43 | 1427 | < .001 | 3.50 | 5.62 |
| Known First | 849 | 5.76 | 8.39 | ||||||
| Known Signature Fixation Count and Questioned Signature Position | |||||||||
| 95% Confidence Interval | |||||||||
| Q Position | N | M | SD | t | df | p | Lower CI | Upper CI | |
| FC Known 1 | Q Right | 849 | 9.48 | 15.92 | -6.76 | 1554 | < .001 | -8.07 | -4.44 |
| Q Left | 849 | 15.74 | 21.76 | ||||||
| FC Known 2 | Q Right | 849 | 14.44 | 16.51 | 6.49 | 1676 | < .001 | 3.44 | 6.43 |
| Q Left | 849 | 9.51 | 14.80 | ||||||
| FC Known 3 | Q Right | 849 | 10.98 | 16.45 | -6.24 | 1616 | < .001 | -7.43 | -3.88 |
| Q Left | 849 | 16.64 | 20.63 | ||||||
| FC Known 4 | Q Right | 849 | 12.41 | 15.82 | 3.09 | 1665 | 0.002 | 0.81 | 3.64 |
| Q Left | 849 | 10.18 | 13.81 | ||||||
| FC Known 5 | Q Right | 849 | 7.19 | 11.52 | -4.47 | 1560 | < .001 | -4.28 | -1.67 |
| Q Left | 849 | 10.17 | 15.61 | ||||||
| FC Known 6 | Q Right | 849 | 8.26 | 11.46 | 0.79 | 1696 | 0.428 | -0.65 | 1.52 |
| Q Left | 849 | 7.82 | 11.30 | ||||||
Figure 8
Mean fixation counts for the Signature Presentation Sequence analyses are presented at the left. Mean fixation counts for Questioned Signature Position analyses are presented at the right. Fixation counts in the Signature Presentation Sequence analyses were significantly greater for questioned-before known than for the known-before-questioned sequence. Fixation counts were significantly greater when the questioned signature was presented on the left than when the questioned signature was on the right. The three highest mean fixation counts for each condition are indicated by the arrows. This demonstrates that participants utilized known signatures 1, 2, and 3 to a greater extent overall than they did known signatures 4, 5, and 6 in the Presentation Sequence protocol. A slightly different pattern is demonstrated in the Questioned Signature Position protocol, where the participants fixated more on signatures 3, 1, and 4 when questioned signatures were presented on the left, and signatures 2, 4, and 3 when the questioned signature was on the right.
Table 6
Regression Coefficients for Predictors of Presentation Sequence and Questioned Signature Position.
| Presentation Sequence | 95% Confidence Interval | ||||||
|---|---|---|---|---|---|---|---|
| Areas of Interest All Knowns | B | Wald | df | P | Odds | Lower CI | Upper CI |
| FC Known 1 (center left) | -0.01 | 1.18 | 1 | 0.278 | 0.99 | 0.98 | 1.01 |
| FC Known 2 (center right) | 0.01 | 1.79 | 1 | 0.181 | 1.01 | 1.00 | 1.03 |
| FC Known 3 (top left) | 0 | 0.26 | 1 | 0.608 | 0.99 | 0.99 | 1.01 |
| FC Known 4 (top right) | -0.03 | 16.44 | 1 | < .001 | 0.97 | 0.95 | 0.98 |
| FC Known 5 (bottom left) | -0.01 | 1.45 | 1 | 0.228 | 0.99 | 0.97 | 1.01 |
| FC Known 6 (bottom right) | -0.01 | 1.63 | 1 | 0.201 | 0.99 | 0.97 | 1.01 |
| Questioned Signature Position | 95% Confidence Interval | ||||||
| Areas of Interest All Knowns | B | Wald | df | p | Odds | Lower CI | Upper CI |
| FC Known 1 (center left) | 0.12 | 98.22 | 1 | < .001 | 1.12 | 1.10 | 1.15 |
| FC Known 2 (center right) | -0.17 | 173.14 | 1 | < .001 | 0.84 | 0.82 | 0.86 |
| FC Known 3 (top left) | 0.06 | 48.84 | 1 | < .001 | 1.07 | 1.05 | 1.09 |
| FC Known 4 (top right) | -0.06 | 31.19 | 1 | < .001 | 0.94 | 0.92 | 0.96 |
| FC Known 5 (bottom left) | 0.02 | 2.97 | 1 | 0.085 | 1.02 | 1.00 | 1.05 |
| FC Known 6 (bottom right) | 0.02 | 2.77 | 1 | 0.096 | 1.02 | 1.00 | 1.05 |
Table 7
Regression Coefficients for Decision Accuracy Predictors.
| 95% Confidence Interval | |||||||
|---|---|---|---|---|---|---|---|
| Predictor Variables | B | Wald | df | p | Odds | Lower CI | Upper CI |
| FC Known 1 | -0.01 | 0.38 | 1 | .537 | 0.99 | 0.98 | 1.01 |
| FC Known 2 | 0.02 | 3.67 | 1 | .055 | 1.02 | 1.00 | 1.04 |
| FC Known 3 | -0.01 | 0.42 | 1 | .515 | 0.99 | 0.98 | 1.01 |
| FC Known 4 | 0.01 | 0.65 | 1 | .422 | 1.01 | 0.99 | 1.03 |
| FC Known 5 | 0.02 | 2.45 | 1 | .118 | 1.02 | 1.00 | 1.04 |
| FC Known 6 | - 0.03 | 4.01 | 1 | .045 | 0.97 | 0.94 | 1.00 |
| Signature Type | 1.30 | 25.76 | 1 | <.001 | 3.65 | 2.21 | 6.02 |
| Signature Complexity | -2.32 | 126.30 | 1 | <.001 | 0.10 | 0.07 | 0.15 |
| Presentation Sequence | 1.00 | 15.38 | 1 | <.001 | 2.73 | 1.65 | 4.50 |
| Questioned Signature Position | -0.12 | 0.38 | 1 | .536 | 0.89 | 0.61 | 1.29 |