The Wyndham Apartments Elevator
Problem Description
I recently lived at the Wyndham Apartments in Chicago. During my short
stay there, I was constantly having problems with the elevator.
The main problem I had with the elevator was with getting the doors to
open and close at the proper times. The elevator controls had a single
button marked "Door", with no indication whether it was to
be used for holding the door open, or for closing the door.
On numerous occations, I attempted to use this button, but it always
seemed to do the opposite of what I wanted. When someone got off of
the elevator, the doors would typically take a long time to close.
Pressing the button would either have no effect, or would keep the
doors open longer. At other times, when I was trying to hold the door
open for someone, I would press and hold the button. Invevitably, the
doors would start to close, forcing me to grab the safety bar on the
doors to hold them open.
On several occasions, I asked other residents of the building whether
the button was for opening the door, closing the door, or something
entirely different. I never received an answer. To this day, I still
have no idea what the function of the "Door" button was.
HCI Analysis
Eberts (1994) argues that a user should develop an accurate mental
model during the use of a system. The affordance provided by the
button was that it controlled the elevator's doors in some
way. Elevators typically have buttons for keeping the doors open and/or
closing them. My mental model for elevators includes the fact that
elevators usually have a "Door Close" button, and less
frequently have a "Door Open" button. I assumed from the
beginning that the "Door" button was for closing the doors,
but my experience did not support this hypothesis.
Apple's interface guidelines (1992), call for feedback from any task a
user attempts. This feedback should be as immediate as possible.
Because neither the button nor the elevator provided feedback, I was
never certain that the button was working correctly. Since I had no
idea what the elevator was trying to do, the gulf of evaluation (Norman,
1988) was difficult to bridge. Even after careful observation of
several attempts at using the button, a clear mental model could not
be formed.
Recommendation
The easiest solution to the probblem would be to change the labeling
of the button from "Door" to "Door Close" or some
other label that gives an accurate description of the button's
function. (Whatever that may be.)
Another, more expensive change would be to bridge the gulf of
evaluation by providing additional indications about what the elevator
is doing. Audio cues (other than the inevitable "ding"),
indicator lights on the doors, or simply a light indicating that the
"Door" button had been pressed would be very helpful.
References
Apple Computer (1992) Macintosh Human Interface Guidlines. Addison
Wesley. [Chapter 1]
Eberts, R. (1994) User Interface Design. Prentice-Hall, Inc. [Chapter 7]
Norman, D. (1988) The Psychology of Everyday Things. New York: Basic
Books [Chapter 2]
rscherle@cs.indiana.edu
Last modified: Thu Mar 25 21:52:40 US Eastern Standard Time 1999