## 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, our actions follow strict biomechanical and motor control laws.
2. Theoretical Foundations
The Keystroke-Level Model (Card, Moran, & Newell, 1980) Card et al. established that human task execution time can be decomposed into primitive motor operators. A central constant is the **Homing Operator ($H \approx 400\text{ms}$)**-the physical time required to move a hand between the keyboard home row and the mouse pointing device.
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.
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.