Dustin Stevens-Baier
COMP 449
9-19-05
Assignment #3
The aim of this assignment is for you to elicit mental models from people. In particular, the goal is for you to understand the nature of people's knowledge about an interactive product in terms of how to use it and how it works.
(a) First, elicit your own mental model. Write down how you think a cash machine (ATM) works. Then answer the following questions (abbreviated from Payne, 1991):
An ATM works by taking a person's card into the machine asking for a pin number that the user then types into the ATM machine. After the number is verified the user is asked questions like: What account do they want to use? Do you want to deposit money or take it out? After the user selects the option that they want the task is performed and the ATM then asks whether or not the user has any more tasks they wish to perform. If not the card and a receipt is spit out of the machine and the transaction is over. The machine is in turn communicating with the banks' databanks about who is using the machine how much money the have and what they want to do with it.
How much money are you allowed to take out?
I am allowed to take out $200.00 at a time. Although I imagine this number changes depending on the bank and person.
If you took this out and then went to another machine and tried to withdraw the same amount, what would happen?
The ATM would say that it is unable to process the transaction and ask you to go inside or try again later.
What is on your card?
The name of the bank is on the card, the card number, the expiration date,
my name. There is also a strip on the back that allows this information to
be processed by the ATM.
How is the information used?
This information is used to allow yourself to make transactions at the ATM, retail store, online shops, and over the phone. The strip on the card is swiped through a machine that reads all the information and then talks to the bank to make sure the available funds are there.
What happens if you enter the wrong number?
If you enter the wrong pin number the machine tells you and asks for the correct one. This usually can only happen for three times then the card is sucked into the ATM machine and you have to go into the bank to get it back. This is a security measure to prevent people from stealing the card and using it.
Why are there pauses between the steps of a transaction?
There are pauses so that the computer in the ATM machine can access the information in the banks computers and bring it up on the screen of the ATM. It is also so passwords and data can be verified.
How long are they? What happens if you type ahead during the pauses?
The pauses are usually just a couple of seconds. I haven't tried typing ahead but my guess is the information is stored in a Queue and then executed when appropriate.
What happens to the card in the machine?
The card is used to access the data about the accounts that you have and it stays in the machine until you are done with the entire transaction.
Why does it stay in the machine?
It stays in the machine to allow access to other accounts and possibly as a security measure to make sure you take your money and card at the same time when you are done.
Do you count the money? Why?
Yes I do count the money. I count it because a number of things could go wrong and you want to make sure that you get the right amount. If the machine runs out of money and gives you one less twenty than you asked for. Or if twenties stick to each other and it gives you two much money.
SECOND PERSONS ANSWERS:
How much money are you allowed to take out?
They are allowed to take out $100.00 at a time.
If you took this out and then went to another machine and tried to withdraw the same amount, what would happen?
The ATM would say that it is unable to process the transaction.
What is on your card?
The card number, the expiration date, my name.
How is the information used?
This information is used to make transactions at the ATM.
What happens if you enter the wrong number?
The machine tells you and asks for the correct one.
Why are there pauses between the steps of a transaction?
There are pauses so that the ATM can verify info.
How long are they? What happens if you type ahead during the pauses?
The pauses are usually just a couple of seconds. They hadn't tried typing ahead.
What happens to the card in the machine?
The card is used to access the data.
Why does it stay in the machine?
It stays in the machine to allow access to other accounts.
Do you count the money? Why?
Not really maybe briefly. Just to make sure.
THIRD PERSON:
How much money are you allowed to take out?
I am allowed to take out $200.00 at a time.
If you took this out and then went to another machine and tried to withdraw the same amount, what would happen?
The ATM would ask you to go inside or try again later.
What is on your card?
There is a strip on the back that allows this information to be processed by
the ATM.
How is the information used?
This information is used to make transactions the ATM.
What happens if you enter the wrong number?
If you enter the wrong pin number the machine tells you and asks for the correct one. If you screw up too many times then it eats the card.
Why are there pauses between the steps of a transaction?
There are pauses so that the computer in the ATM machine can catch up.
How long are they? What happens if you type ahead during the pauses?
The pauses are usually just a couple of seconds. They hadn't tried typing ahead.
What happens to the card in the machine?
The card is used to access the data about the accounts.
Why does it stay in the machine?
It stays in the machine until you get your money.
Do you count the money? Why?
Not usually.
(b) Now analyze your answers. Do you get the same or different explanations?
I get the same answers for most of the questions like what is an ATM used and what is on the card. I count my money but the other two don't really. Everybody recognized that the card stayed in the machine until you take your money out.
What do the findings indicate?
The findings indicate that most people have the same mental model of how ATM's work they are like a monitor for a central computer in a bank that holds everyone's info.
How accurate are people's mental models of the way ATMs work?
Not knowing exactly how ATM's actually work makes it difficult to know for sure but it seems like they are generally accurate that people recognize that the ATM is contacting another computer to verify this information.
How transparent are the ATM systems they are talking about?
It apparently is fairly transparent sense most users appear to understand what is going on fairly well.
(c) Next, try to interpret your findings with respect to the design of the system. Are any interface features revealed as being particularly problematic?
The way the buttons are lined up with the screen sometimes makes it difficult to tell which option the user is selecting. Another problem can be that the ATM has to access the information off of the ATM card before accessing the database in the bank. This card is used along with the pin as a security measure this step could be eliminated.
What design recommendations do these suggest?
This interface could be lined up better or the buttons could actually be on the screen that would enable users to be more confident and comfortable with their selections. This design could be changed by making the security information something biometric like retina scan or fingerprints that would make the system safer and make it so an ATM card does not have to be carried around.
(d) Finally, how might you design a better conceptual model that would allow users to develop a better mental model of ATMs?
I would explain the system as three steps. The banks information is like a monitor and a CPU, the ATM is the monitor that can access certain information off of the CPU but it needs security clearance to do so. The clearance is given when the card and pin number that is associated with the card and that account are given. The information is then pulled off the database and allows the ATM to perform certain functions on this information.