Module Useri.Human

module Human: sig .. end
Human factors.


System latency feelings

These values are from here.

val noticed : Useri.Time.span
noticed is 0.1s, the time span after which the user will notice a delay and feel that the system is not reacting instantaneously.
val interrupted : Useri.Time.span
interrupted is 1.s, the time span after which the user will feel interrupted and feedback from the system is needed.
val left : Useri.Time.span
left is 10.s, the time span after which the user will switch to another task and feedback indicating when the system expects to respond is needed.
val feel : unit -> [ `Interacting | `Interrupted | `Left ] React.signal
feel () is a signal that varies according to user latency constants:

Touch target and finger sizes

These values are from here.

val touch_target_size : float
touch_target_size is 9.mm, the recommended touch target size in millimiters.
val touch_target_size_min : float
touch_size_min is 7.mm, the minimal touch target size in millimeters.
val touch_target_pad : float
touch_target_pad is 2.mm, the minimum padding size in millimeters between two touch targets.
val average_finger_width : float
average_finger_width is 11.mm, the average adult finger width.