Figure 1
Examples of a text-based (top), stylized (middle), and mixed style (bottom) signature.
Table 1
List of stroke features extracted from MovAlyzeR and their definitions1
| Variable | Definition |
|---|---|
| Absolute Size | Absolute size of a vertical stroke in cm, calculated from the vertical and horizontal sizes |
| Average Absolute Velocity | Average (amplitude/time) absolute vertical velocity for a single stroke, in cm/second |
| Average Normalized Jerk | A measure of handwriting smoothness across all strokes, normalized for stroke duration and length |
| Average Pen Pressure | Average of pen pressure values over a stroke (ranging from 0–2047 units) |
| Stroke Duration | Time interval in seconds for a single vertical stroke, identified as movement occurring between two successive x-axis zero-velocity crossings (i.e. at the point of a change in stroke direction). |
| Horizontal Size | Horizontal vector difference between the beginning and end of a stroke, in cm |
| Loop Surface | Area of the loop enclosed by the previous and present stroke, in cm2 |
| Number Peak Acceleration Points | A measure of handwriting smoothness measured at the stroke level defined as the number of acceleration inversions (i.e. changes in direction) |
| Number of Strokes | Segmentation by absolute velocity minima, similar to number of turning points |
| Peak Vertical Acceleration | Instantaneous vertical acceleration, in cm/sec/sec |
| Peak Vertical Velocity | Instantaneous vertical velocity, in cm/sec |
| Road Length/Trace Length | Length of segment in cm from beginning to end |
| Slant | Stroke angle and its direction (see Stroke Duration for definition of segment) in radians |
| Straightness Error | Normalized standard deviation of the stroke trajectory from a straight line |
Table 2
Mean and standard deviation for each kinematic variable and complexity score, separated by style.
| Stylized (n = 34) | Mixed (n = 44) | Text-Based (n = 30) | |||||
|---|---|---|---|---|---|---|---|
| Variable (Mean) | Stroke Direction | Mean | SD | Mean | SD | Mean | SD |
| Duration, sec | Down | 0.13 | 0.04 | 0.14 | 0.03 | 0.14 | 0.02 |
| Up | 0.15 | 0.04 | 0.17 | 0.05 | 0.17 | 0.03 | |
| Peak Vertical Velocity, cm/s | Down | –7.99 | 3.84 | –6.53 | 3.03 | –4.73 | 1.74 |
| Up | 7.54 | 3.97 | 6.21 | 2.93 | 4.45 | 1.52 | |
| Peak Vertical Acceleration, cm/sec/sec | Down | –209.00 | 135.49 | –93.46 | 452.53 | –107.98 | 44.91 |
| Up | 190.42 | 113.62 | 185.16 | 390.96 | 95.29 | 40.03 | |
| Horizontal Size, cm | Down | –0.39 | 0.56 | –0.16 | 0.32 | –0.07 | 0.11 |
| Up | 0.94 | 0.76 | 0.53 | 0.32 | 0.30 | 0.13 | |
| Straightness Error | Down | 0.03 | 0.02 | 0.04 | 0.02 | 0.04 | 0.02 |
| Up | 0.03 | 0.02 | 0.04 | 0.02 | 0.05 | 0.02 | |
| Slant, radians | Down | –1.78 | 0.41 | –1.74 | 0.37 | –1.72 | 0.29 |
| Up | 0.77 | 0.33 | 0.85 | 0.30 | 0.87 | 0.24 | |
| Loop Surface | Down | 0.00 | 0.19 | 0.02 | 0.06 | 0.01 | 0.01 |
| Up | 0.00 | 0.10 | –0.02 | 0.03 | 0.00 | 0.01 | |
| Absolute Vertical Size | Down | 1.06 | 0.55 | 0.74 | 0.37 | 0.45 | 0.13 |
| Up | 1.32 | 0.70 | 0.89 | 0.48 | 0.54 | 0.11 | |
| Average Absolute Velocity | Down | 8.53 | 4.35 | 5.99 | 2.74 | 3.65 | 1.10 |
| Up | 9.53 | 5.12 | 6.24 | 2.93 | 3.84 | 0.99 | |
| Roadlength/Trace Length | Down | 1.21 | 0.65 | 0.92 | 0.49 | 0.55 | 0.16 |
| Up | 1.54 | 0.84 | 1.12 | 0.71 | 0.70 | 0.17 | |
| Average Normalized Jerk | Down | 23.22 | 33.54 | 52.51 | 97.40 | 54.12 | 75.89 |
| Up | 23.60 | 33.90 | 53.69 | 99.83 | 52.84 | 71.20 | |
| Number of Acceleration Peaks/Stroke | Down | 1.34 | 0.45 | 1.39 | 0.38 | 1.32 | 0.22 |
| Up | 1.56 | 0.38 | 1.76 | 0.65 | 1.68 | 0.33 | |
| Total number strokes | Both | 32.97 | 12.93 | 52.84 | 20.50 | 81.84 | 21.11 |
| Mean Pen Pressure | Down | 553.02 | 161.28 | 535.28 | 106.58 | 499.72 | 100.72 |
| Up | 521.55 | 172.03 | 485.64 | 118.21 | 448.16 | 94.54 | |
| Complexity Score | 3.14 | 1.06 | 3.54 | 0.90 | 4.19 | 0.60 | |
Table 3
Formulas and results from multiple regression analysis for 30 text-based, 44 mixed, and 34 stylized signatures. Shown are kinematic variables reaching statistical significance as independent predictors of complexity perception.
| Signature Style | Kinematic Model | ANOVA | R2 |
|---|---|---|---|
| Stylized | Complexity = 0.16 – (0.802*Horizontal Size Down) + (0.1217*Peak Vertical Velocity Up) – (0.0824*Average Absolute Velocity Up) + (0.0769*Total Strokes) | F(4,29) = 23.37; p < 0.0001 | 0.76 |
| Mixed | Complexity = –1.75 + (0.14*Peak Vertical Velocity Down) – (0.00052*Peak Vertical Acceleration Down) – (0.8557*Slant Down) + (15.75*Straightness Error Up) + (1.4835*Slant Up) + (0.246*Average Absolute Velocity Up) – (0.638*Road length Up) + (0.0363*Total Strokes) | F(8,35) = 16.54; p < 0.0001 | 0.79 |
| Text-Based | Complexity = 3.71 – (13.371 * Duration Down) + (1.4511*Road length Up) + (0.0164*Total Strokes) | F(3,26) = 21.18; p < 0.0001 | 0.71 |
Figure 2
Scatterplot showing relationship between the composite kinematic scores (x-axis) and FDE perception of signature complexity (Y-axis) with line of best fit for text-based signatures.
Figure 3
Scatterplot showing relationship between the composite kinematic scores (x-axis) and FDE perception of signature complexity (Y-axis) with line of best fit for stylized signatures.
Figure 4
Scatterplot showing relationship between the composite kinematic scores (x-axis) and FDE perception of signature complexity (Y-axis) with line of best fit for mixed style signatures.