Mouse idle and the fatigue tells nobody talks about
Most fatigue tracking ignores the mouse entirely. Idle stretches and movement cadence are quieter than camera signals but harder to game, and they line up with the rest of the read.
- Mouse idle stretches grow with session length and predict fatigue better than mouse speed.
- Mouse signals are quieter than camera signals but harder to game.
- They are most useful as a confirmation layer for what the camera is already telling you.
The signal nobody talks about
Mouse activity gets a fraction of the attention keyboard or camera signals do. Part of that is fashion. Part of it is that mouse data alone is not very interpretive — pull it out of context and it tells you almost nothing.
As a *confirmation layer* for the rest of the read, though, it is one of the more useful inputs Sarenica has. Quieter than camera. Harder to game than keyboard. Always there.
Distance and speed: read across comparable blocks
Sarenica records cumulative mouse distance and average speed per minute. Both move with task type more than strain. A design block has wildly different mouse metrics from a reading block, even on the same day.
Where they get useful is comparing comparable blocks. If your morning design sessions average 700 px/sec and your afternoon design sessions average 480 px/sec, that is a real signal. Same task, different cadence. Something happened between morning and afternoon.
Idle stretches: the actual fatigue tell
The mouse signal that earns its place is idle minutes — stretches longer than about 30 seconds with no movement at all. Not the same as breaks (you might be reading, or thinking), but they accumulate in a pattern that tracks tightly with session length.
Short sessions accumulate almost no idle time. Long sessions accumulate a lot — and the rate accelerates in the last third. That accelerating shape is exactly what fatigue signals from the camera and keyboard show in parallel. When three independent sources agree, the report has earned the right to be confident.
Click rate vs movement
Click rate often diverges from movement rate, and that divergence carries information. Lots of clicks with little movement is a navigation-heavy task. Lots of movement with few clicks is a passive consumption pattern. Each shows up differently in fatigue burden.
The pattern closest to a real strain signal is *high movement with declining click rate* within the same session. Your hand is still moving but you are doing less with each click. That is what late-session drift looks like in mouse data.
Why mouse never calls fatigue alone
Mouse data on its own is rarely conclusive. It earns its place in the weekly report by *lining up* with camera and keyboard signals. When eyes-closed seconds, head-pose drift, and mouse idle all rise together in the same session, the weekly report has a far stronger claim than any of them alone.
That is also why Sarenica refuses to call fatigue from mouse data alone. The signal is too noisy out of context, and the cost of a false positive is wrecked trust in the rest of the read. Conservative reads compound; sloppy ones erode.
- Distance and speed → best read across comparable blocks.
- Idle minutes → best read against session length.
- Click-rate divergence → best read inside a single session.
