1. The Single Locus of Attention
A genuine web interaction session is produced by a human user with one central cognitive processor and a single locus of physical attention. When filling out a form, human actions follow strict biomechanical and motor control laws.
[!NOTE] Central Attentional Bottleneck Theory (Pashler 1994) confirms that human central cognitive processes cannot simultaneously program two distinct motor effectors (e.g. right hand typing and left hand cursor targeting) without severe latency degradation.
2. Theoretical Foundations
The Keystroke-Level Model (Card, Moran, & Newell, 1980)
Card et al. established that human task execution time decomposes into primitive motor operators:
- Homing Operator ($H \approx 400\text{ms}$): Physical time required to move a hand between keyboard home row and mouse.
- Mental Preparation ($M \approx 1.35\text{s}$): Cognitive pause before initiating an unfamiliar action chunk.
- Keystroke Burst ($K \approx 80-200\text{ms}$): Typing cadence of skilled typists.
Gaze-Cursor Coupling (Huang, White, & Buscher, ACM CHI 2012)
Eye-tracking studies demonstrate that cursor position naturally lags visual gaze by an average of 700ms (ranging from 250ms to 1s). The visual system fixates on an input element before motor commands direct the cursor.
| Cognitive Operator | Calibrated Human Range | Automated Bot Profile | Metric Code |
|---|---|---|---|
| Mouse Idle During Typing | 0.92 – 1.00 ratio | 0.10 – 0.65 ratio | MIDT |
| Hand Homing Switch Latency | 250ms – 550ms | 0ms – 40ms | COC |
| Keystroke Onset Lag | 180ms – 420ms | < 30ms or > 1200ms | KOL |
| Cursor Lead before Focus | 80ms – 400ms lead | Instant / 0ms lead | PPF |
3. Translating Biomechanics into CMCC Features
CORROBORATE formalizes these cognitive principles into mathematical features:
- MIDT (Mouse-Idle-During-Typing): Verifies that the mouse remains stationary while typing bursts occur.
- KOL (Keystroke-Onset Lag): Verifies that typing begins within a plausible human reaction window (150–450ms) after an input field click.
- PPF (Pointer-Precedes-Focus): Confirms that ballistic cursor motion leads focus acquisition.