Fitting the machine to the user and fitting the user to the machine:
Prologue: Names and definition
A. Other common names for the field
- Human factors
- human factors engineering
- human engineering
- -> engineering psychocology
B. Definition (p.234): The science of
a) designing machines for the human use and
b) determining appropriate behaviors for the efficient operation of ma-
chines.( from machine to nucliar power’s machines).
->two goals that led to development of the field
-fitting the machine to the user
- fitting the user to the machine
Part 1: Historical development
A. Design the machine and ignore the user. Not effective E.g. WW2
- Design of Army tanks (p.243)
- - too much noise
- - poor visibility around the distance of tank was poor, failing the digits
- - seating posiitons caused back and neck injuries
- --> more damage to operators than enemy!
- Altitude displays in airplanes: too complex (took 7 sec to read; misread
12% of time). ex. it looks like a clock 700 feet (or 10700 feet)??the dis-
play was misleading in accurance of misearuaring.
B. Design the machine and then fit user to the machine. Two ap-
1. Select ppl who fit the machine. E.g.
- if strength required, select strong users
- if intellegence required, select intelligent users
Problem: not always possible to find ppl who fit the machine. E.g.
- women in WW2 weapons factories were not very productive. Why?
- - not smart enough? No!!
- - machines designed for men- women didnt fit the machines (but no
men to use them)
2. Train people to use the machine. E.g.
- give pilots more training with altitude displays
- time and motion studies: train workers to move more efficiently when
using machines (eliminate unnecessary movement)
- training was time consuming and expensive to provide - Machines were becoming so complex that no amount of training would
be effective. ( they exceeded human capabilities to operate them).
C. Design the machine so it fits the user
1. Two early examples that it can be done:
- Taylor(1898): Changing the design of shovels can increase productivity
- The Gilbreths (p.237-38): Can increase movement efficiency by re-
designing machines and the workplace. E.g.
- use scaffolds when laying bricks
- put shelves in fridge doors
- put foot pedal on trash cans
- have nurses provide instruments to surgeons
2. Additional examples that designing machines to fit the user must be
a) Technological disasters:
- Three Mile island (1979): a nuclear power plant in US comes very close
to a meltdown.
- Bhopal, India (1984): Chemical spill kills 400, injures 200000
- Chernobyl (1986): explosion at nuclear power plants kills 300; contam-
inates millions of acres
- -> what do they have in common? Human factors were ignored when
the technology was designed!
The control room at Three Mile Island was very complex.Complexity is
amde by the poor of layouts of controls: operator has to reach for con-
trols with suppoort from his hand. Operator needs a special ladder to see
some of the contorls. What if ladder is in wrong place at a critical mo-
b) An increase in product liability and personal injury lawsuits:
- poorly designed products can cause injuries
- so products must be designed to be safe (dont change the user;
change the product!)
c) The development of personal computers:
- originally designed to be functional, but not user-friendly.
- e.g. command-line interface required learning a new language. e.g. to
underline : (CTL U) world (CTL u)> RTFM
- difficult to learn; easy to make mistakes
- The apple Macintosh’s approach:
- - Rely on what users are already familiar with- an office enviroment
(desctops, files, folders, trash can).
- - design the computer to match this familiar enviroment
- - today nearly all popular software uses this easy windows enviroment
(with a grphical user interface).
ex. sa-250, re-450,b-90,-bo 185, ph-150
Part 2: The systems concept in engeneering Psychology
Machines and ppl who use them are not sepaprate entit