Fitting the machine to the user
Fitting the user to the machine
A. Other common names for the field:
Human factor engineering
B. Definition p. 226: the science of
a. designing machines for human use and
b. determining appropriate behaviors for the efficient operation of machines.
- machines includes – thump tacks to nuclear missiles
= 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 approach seen during WW2.
- Design of army tanks (p.235) – there was no problem with the tanks, no consideration
was given to the ppl using the tanks.
- Eg: too much noise, couldn’t talk to eachother,
- Poor visibility, could not see near the tank and would fall into ditches.
- Seating position caused back and neck injuries,
- More damage to the operators than the enemy!
Altitude display in airplanes: too complex (took 7 sec to read; misread 12% of the time).
- 700 feet (or 10,700 feet)?
B. Design the machine and then “fit” user to the machine.
1. Select people who fit the machine eg:
- if strength required, select strong users
- if intelligence required; select intelligent users ( this is true in I-O psychology; finding
the right person for the job)
Problem: not always possible to find people who “fit” the machine eg:
- women in WW2 weapons factories were not very productive. Why?
- Not smart enough? No!
- But, machines were designed for men – women didn’t “fit” the machines (but men were
not allowed to use them).
2. Train people to use the machine. Eg.,
- 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 the training would be effective
(they exceeded human capabilities to operate them).
- It was assumed that the machines was a constant, the user can be changed, so the user
would have to fit the machine.
- However the machine is NOT a constant according to engineering psychologists.
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 (p. 229).
- The Gillbreths (p.229-230): can increase “movement efficiency” by redesigning
machines and the workplace. Eg:
- Use scaffolds when laying bricks; - minimize the amount the reaching the brick makers
would have to do.
- Put shelves in fridge doors;
- Put a foot pedal no trash cans;
- Have nurses provide instrument to surgeons during operation.
2. Additional examples that designing machines to fit the user must be done
a. Technological disasters:
- Three Mile island (1979): a nuclear power plant in US comes very close to a meltdown.
- Bhopal, India (1984): chemical spill kill 400, injured 200,000
- Chernobyl (1986): explosion at nuclear power plant killed 300; contaminates millions of
- What did they have in common? Human factors were ignored when the technology was
Complexity is made worse by the poor layout of controls:
- Operator has to reach for controls with support from his hand.
- His knees are very close to the buttons
- Another picture:
- Operator needs a special ladder to see some of the controls. What if ladder is in wrong
place at critical moment?
B. An increase in product liability and personal injury lawsuits:
- Poorly designed products can cause injuries
- So products must be designed to be safe (don’t change the user; change the product!)
c. The development of personal computers:
- originally designed to be “fuctional”, But not “user-friendly”
- Eg: command-line interfere required learning a new language. Eg: to underline: [Ctl U]
word [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 environment (desktops, files,
folders, trash cans).
- Design the computer to match this familiar environment. - Today nearly all-popular software uses this easy “windows” environment (with a
graphical user interface).
Part 2: The “systems” conc