PS-INP-158 · r1
INPUT
OBSERVED
ENGAGED · ONGOING
POINTER CONTINUITY LOSS
The hand knows where it is going; the eye has to find out where the pointer was left.
01 DEFINITION
Condition in which the control the hand moves exists on one surface at a time while the operator attends to several, so the position of the pointer becomes a state the operator has to hold and recover rather than one the display carries.
02 CONDITIONS
UNCERTAINTY
MISSING
Where the pointer is is not shown anywhere; it is inferred or searched for.
TIME PRESSURE
SHORT
The cost appears in the seconds between deciding and acting.
ERROR ASYMMETRY
SYMMETRIC
Losing the pointer costs the same in either direction of movement.
OPERATOR STATE
CONCURRENT
Attention is spread across surfaces while the control is on one of them.
03 WHERE IT APPEARS
MEDICALAttention spans several displays while one control moves between them, and the interval before an action is spent locating the control rather than choosing.
FINANCEAcross a bank of screens the position of the pointer is carried by the operator rather than by the surfaces, and is recovered by looking.
INDUSTRIALControl room surfaces each assume they hold the pointer, and none of them shows where it actually is.
TELECOMOperations displays multiply faster than the means of moving between them, so the cost of the move grows while the cost of the decision does not.
DEFENSETwo or more large surfaces are attended at once and the pointer exists on only one of them at a time.
04 WHAT AEON WORKED THROUGH HERE
Watching operators move between surfaces showed that the delay was rarely in deciding and often in re-finding — the moment between knowing where to act and seeing where the pointer had been left. The work went into that moment rather than into the number of surfaces.
What stays unresolved is whether a pointer that announces itself solves the problem or moves it — a marker large enough to be found without searching is large enough to cover what was being looked at.