Conceptual Model Activity

What's the Point?

Conceptual models are key in design and use of any system. For example, if your home is too hot and you want to cool it down as quickly as possible, you might be tempted to set the thermostat at 55 degrees rather than 68 degrees, because you think it will cool down faster. But you'd be wrong, because that would be using the wrong conceptual model of a cooling system, which usually has no levels of power -- it's simply on until the thermostat level is reached, and then it's off.

Conceptual models are a way of thinking that must be shared between the designer and the user. Sometimes that means a common language or understanding.

Can you describe what makes a good conceptual model vs. a bad one?

How's It Done?

You're going to do two (2) short activities with conceptual models, one about ATMs, and one in which you try to describe a drawing for someone else to draw.

Conceptual models can be represented in lots of ways, e.g. flow charts, narratives, outlines, etc. Choose whatever representation you want for the ATM bit, as long as you can get it up into this wiki later.

If you want to make a quick pencil sketch and get it scanned, that's fine. One easy way to scan a paper is to fax it to my work fax, which will turn it into a PDF and I can then attach it to the Week 2 activities page for you. To do this, fax it to 973-939-8421. I don't need a coversheet; this goes direct to me, but do put your name on it.

If you're doing this in class, I'll scan them all for you.

You Do It!

Part 1: ATMs

Do this part individually.

1. Think about an ATM cash machine and answer these questions to yourself, maybe taking brief notes so that you can refer back to your answers:

1. 1. What kind of bad user experiences are possible with an ATM, e.g. it gives you the wrong amount of money?
   2. What information is on your ATM card?
   3. Is there a limit to the amount of cash you can take out? If you take out that amount at one machine, can you go across town and get more from another ATM?
   4. Why do some machines keep your card during the transaction, while others don't? Are there pros and cons?
   5. Why do many machines ask, early on in the transaction, whether you will want a receipt?
   6. Do you count the money that comes out? Why or why not? What does this mean about the design of the ATM?
   7. Some ATMs charge you a fee like $2 if the ATM is not part of your bank. Does this fee actually pay for some service, i.e. help that bank reduce some cost that it incurs? If so, what?
   8. Are ATMs on the Internet? If so, does that mean that a machine sitting in convenience store has an Internet connection? Could a savvy Internet hacker eavesdrop on your transaction?
   9. Some ATMs allow "Fast Cash" withdrawal and offer amounts like $40, $75, etc. How are those amounts set? Do they differ from machine to machine? Why?
   10. How much cash does an ATM typically have in it?
   11. How often does a bank or ATM company employee have to come service the machine?
   12. What kind of things can go wrong with an ATM that would need servicing?

2. Draw, Write, or Sketch something that, to you, represents your conceptual model of how an ATM works. It might be a script, e.g. first you do this, then the machine does that. Or it might be a sketch with boxes for where the card goes and the money comes out, etc. Whatever makes sense to you. You might think of it explaining to a naive friend how an ATM works.

• Just spend 10 - 15 minutes on this.
• There's no right answer. The point is for you to grapple with representing your thoughts about ATMs in a concrete form.

Now find a partner, from class or a friend or family member. You just need another person who has used an ATM. Ask for 10-15 minutes of their time.

3. Explain to the person that you're thinking about how ATMs work and that you had to answer the questions above about them. Ask these questions to your partner, just verbally. See if your partner's answers are different than yours. If you're surprised, make a note so you can write about it in your activities post.

4. Now ask the person if they could do a brief drawing activity with you. You have two simple pictures, and you'd like the other person to try to draw what's on them, purely based on your talking about what's on your pictures. Don't show the other person your pictures! You can't gesture, you can't point to their drawing. Imagine you're doing this over the phone. (You could do it over the phone, but it's harder to get their drawing afterward.) You could have the other person do the talking and you do the drawing if you like.

• Spend just a couple minutes on each drawing. Emphasize to the partner that you don't want Picasso; this is just for fun and learning.
• If you're on-campus, don't download this link! (It's a spoiler) pictures_to_draw.pdf: Pictures to draw

5. Picture 1 will probably be harder for the other person to draw accurately or harder for you to describe than PIcture 2. Why? Talk with your partner about why, and write your thoughts on your activity post. What does this have to do with conceptual models of the world?

Explain It!

Write a blog post that includes:

• Were there any surprises for you with the ATM cognitive modeling?
• What did you notice from the drawing exercise?
• Your criteria by which you think a conceptual model should be evaluated. What makes a good one?

Now Think Again

The drawing exercise might make you appreciate what an achievement it was when Adobe introduced Postscript in 1984. Postscript is a computer language used inside printers largely in the 80s and 90s (though still today also) for describing exactly what should be drawn on a page by the printer. It was impressive for capturing a picture and fonts based on vectors, so they could scale smoothly to any size, rather than just dots.

For PostScript to be created, the designer had to create a conceptual model of the graphics world that would work with everyone else's graphics and printing needs.

Wikipedia on PostScript

• REU_HCI_Day2.ppt: Slides on sensory properties and their role in HCI