PS-INP-162 · r1
INPUT
OBSERVED
ENGAGED
REACH AND READ SPLIT
The hand is held where it can hold; the eye goes where the hand cannot follow.
01 DEFINITION
Condition in which the way a surface has to be held in order to be carried decides which parts of it the hand can reach, and those are not the parts the eye settles on, so acting and reading compete for opposite regions of the same area.
02 CONDITIONS
UNCERTAINTY
MISSING
Nothing on the surface shows where the reachable region ends; it is learned by failing to reach.
TIME PRESSURE
SHORT
The cost appears in the seconds between deciding to act and finding somewhere to act from.
ERROR ASYMMETRY
SYMMETRIC
Losing area to controls and losing controls to area cost about the same, which is why neither settles the question.
OPERATOR STATE
CONCURRENT
The operator is carrying the surface and using it at the same time; the grip is not negotiable.
03 WHERE IT APPEARS
MEDICALA device held in both hands at the bedside puts its controls under the thumbs and its image in the middle, and the middle is what the examination is for.
LOGISTICSHandheld terminals are gripped to be carried all shift, and the grip decides which part of the screen is a control and which part is only something to look at.
INDUSTRIALPortable panels taken to the equipment are held rather than rested, so the reachable band and the readable field are different parts of one small surface.
CONSTRUCTIONA screen carried around a site is held at the sides, and the drawing that justifies carrying it needs the centre.
MOBILITYControls placed within reach of a seated posture are placed away from where the eye is already looking.
DEFENSEA two-handed carried console reserves its edges for the hands and its centre for what the hands are acting on.
04 WHAT AEON WORKED THROUGH HERE
The grip was fixed before the layout was: both hands hold the device, so the reachable area is two narrow strips and the centre is not one of them. Putting the controls where they could be reached put them where the view had to give way. The work went into which commands earn the strips, and what the centre owes in return.
What stays unresolved is what belongs at the edge once the edge is the only place a command can live — every control moved there is taken from the margin the reading needed, and the reading is why the command is being issued at all.