Welcome back. The topic for this lecture is the Gulf of Execution and the Gulf of Evaluation. This video draws on work first done by Donald Norman and his book, The Design of Everyday Things. Now, I want to start with just a simple example to illustrate sort of the foundation for this concept. So Don Norman talked about different stages of action and he said, if you want to achieve a goal, you have to form an intention to take some action to achieve that goal. You have to figure out what actions you're going to take, you have carry out the actions and those actions always involve acting in the world, changing the world or the environment. And for our purposes, that environment typically is a computer system. Then you have to perceive and interpret what happened, what changed, if anything in the environment and then you have to evaluate progress towards the goal. Did I achieve the goal? Did I make progress toward the goal or not? So, I'll just talk through a simple example of this. So suppose I want to clean up my desktop interface and I've got a shortcut to Spotify on my Windows desktop and I decide, I want to remove it now. So, that's forming an intention to act. I then have to figure out how to do it and actually carry out my intention, carry out my plan. And so I can figure out or I already know, I can put this into the recycle bin by dragging and dropping it over to the recycle bin and I can use the mouse to actually perform the drag and drop action. And then once I do that, I have to see what changed and I might immediately notice that I don't see the shortcut on the desktop anymore and then I can evaluate progress toward my goal. Well, in this case, it's very simple if the short cut isn't visible any more on my desktop interface. I think I've achieved my goal. So, just a really simple example that illustrates the idea of these stages of action. But as you might be thinking already, things can go wrong with this whole process and they can go wrong at different stages. For example, I might not know about the recycle bin or I might not see the recycle bin icon even if I do know about this concept. I might not know about drag and drop or I might have a hard time executing the drag, and drop action. Maybe my motor skills aren't good. Maybe I can't see that well. Maybe the mouse isn't working right and I just have a hard time actually executing that action. So, there's names to describe two particular types of failures that can occur through this process. One is the Gulf of Execution and one is the Gulf of Evaluation. Now the Gulf of Execution happens, as it sounds like if you have trouble executing an intention and this can occur. Well, think of these questions. Does the system provide actions that correspond to the user's intentions? That is, is there a way to do what you wanted and can the user figure out that these are the right actions? Can you actually do these actions? And any difficulty, any problem and going from your intentions from your plan to available actions is called the Gulf of Execution and the Gulf of Evaluation is the other side of things. You can ask yourself, does the system provide physical representations that is displays or outputs that can be easily perceived, easily noticed and interpreted in terms of the users goals and intentions? That is can you tell, have you made progress toward achieving your goals? And the Gulf of Evaluation then represents the amount of effort or how difficult it is to interpret the physical state of the system that is what you see in the system and determine have you made progress toward your goal. So let's take a couple examples, because what we'll see is that these two gulfs account for many Hall of Shame User Interfaces, that is bad user interfaces. So, I'm going to take first an example of the Gulf of Execution. So, what you could see on this slide is a picture of a conference room that I go in to all the time. And if you'll notice, there's a screen at the front of the room. So often, we want to project on to that screen. And when anybody does this, you want to dim the lights at the front of the room by the screen. So that when you project information on the screen, it's more visible. Well, so I form an intention to dim the lights at the front of the room. Well, I have to figure out where are the controls and I have to figure out how to actually operate those controls to dim the light at the front of the room. Yeah, so my goal is to dim the lights in front of the room and I have to find out where are the controls. Now perhaps, not surprisingly. If I look at the back of the room, there is a nice lights switch right by the door and that's where the controls are. Pretty much where you'd expect. Now if you zoom in on those controls though, you have this issue. Which of those two switches, there's one on the left, one on the right is for the front lights and which for the back? For me, at least, the answer is not obvious. And although I've probably done this dozens of times, I'd typically just do it by trial and error. So, the problem of which switch should I press is a problem for me on an ongoing basis. And since the answer to this is not clear to me, there is a Gulf of Execution. Let's take another example, a Gulf of Evaluation Example. So as I was preparing these slides, I downloaded some picture files onto my computer and you can see them over there and you see the names of those picture files. Well, which ones of these is the close-up of the light switch that I used a couple slides back? Which one of those file names represents the light switch picture? And if it is not clear to me from this display, there is a Gulf of Evaluation. Now, you might be thinking that there are other representations in the Windows File Explorer that does let me get a preview of the actual pictures. That's true, but this is the default configuration that I use for various purposes. And in this display, it is not clear to me which of these pictures indicates the picture of the light switch. And therefore, there is a Gulf of Evaluation. Also for another couple of examples, remember that in another video, we gave the example of controlling the temperature of the fresh food and freezer compartments of a refrigerator. And in that example, we saw both a Gulf of Execution and a Gulf of Evaluation. So going back to the action model that we introduced earlier, it's useful to note that we can use this model as a guide for creating good designs. We can ask ourselves a series of questions. You can ask yourself things like, how easily can the user determine what the system is for, determine what can be done with it? How easy is it for the user to tell what actions are possible to be done with the system? How easy is it for the user to identify and carry out the appropriate actions? How easy it for the user to perceive and interpret what happened? And how easy is it for the user to evaluate progress towards the goal? And as we shall see soon, there are useful design principles that help us answer these questions. A key set of these principles include visibility, feedback, mappings and constraints and these will be coming up soon. That's it for the Gulf of Execution and the Gulf of Evaluation, and that's all until next time.
