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Dialogue: 0,0:00:01.94,0:00:05.60,Default,,0000,0000,0000,,In this video, we are going to talk about mental models,
Dialogue: 0,0:00:05.60,0:00:09.02,Default,,0000,0000,0000,,and the questions that we are going to tackle here are:
Dialogue: 0,0:00:09.02,0:00:15.19,Default,,0000,0000,0000,,“What makes an interface learnable?“ and “What leads to errors that people make in user interfaces?”
Dialogue: 0,0:00:15.19,0:00:19.100,Default,,0000,0000,0000,,And to do that, I’d again like to start with an example from the physical world.
Dialogue: 0,0:00:19.100,0:00:23.58,Default,,0000,0000,0000,,Here we are outside the Computer Science building at Stanford.
Dialogue: 0,0:00:23.58,0:00:28.01,Default,,0000,0000,0000,,And what I’d like to show you is an example of a user interface error.
Dialogue: 0,0:00:28.01,0:00:34.13,Default,,0000,0000,0000,,It’s really simple one: Our department and its front door has two doors.
Dialogue: 0,0:00:37.08,0:00:44.96,Default,,0000,0000,0000,,It both have exactly the same handle on them. However, the door on the right never actually opens.
Dialogue: 0,0:00:44.96,0:00:53.89,Default,,0000,0000,0000,,So, if I go to use this door right here, 24-hours-a-day 7-days-a-week it never works — it’s locked!
Dialogue: 0,0:00:53.89,0:00:58.63,Default,,0000,0000,0000,,So why does it have the same handle as the other that does open?
Dialogue: 0,0:00:58.63,0:01:03.57,Default,,0000,0000,0000,,And you can see right here that a whole lot of people have tried using this handle.
Dialogue: 0,0:01:03.57,0:01:06.35,Default,,0000,0000,0000,,In fact, faculty who have been around for years
Dialogue: 0,0:01:06.35,0:01:11.42,Default,,0000,0000,0000,,still often make the mistake of grabbing the wrong door.
Dialogue: 0,0:01:11.42,0:01:14.100,Default,,0000,0000,0000,,This would be a whole lot better if this door had no handle here.
Dialogue: 0,0:01:14.100,0:01:17.91,Default,,0000,0000,0000,,You could still exit — you can see this part right here —
Dialogue: 0,0:01:17.91,0:01:23.26,Default,,0000,0000,0000,,but if want to enter, you would know where to grab and which door to use.
Dialogue: 0,0:01:24.58,0:01:26.45,Default,,0000,0000,0000,,Let’s say you’ve got a refrigerator,
Dialogue: 0,0:01:26.45,0:01:31.31,Default,,0000,0000,0000,,and the problem is that he freezer is too cold, but the fridge is all just right.
Dialogue: 0,0:01:31.31,0:01:35.59,Default,,0000,0000,0000,,This refrigerator has two dials: One of them is labelled A through E,
Dialogue: 0,0:01:35.59,0:01:39.08,Default,,0000,0000,0000,,the other is labelled with numbers, 3 through 7.
Dialogue: 0,0:01:39.08,0:01:41.01,Default,,0000,0000,0000,,and there’s an instruction manual
Dialogue: 0,0:01:41.01,0:01:45.62,Default,,0000,0000,0000,,that lists combinations of letters and numbers for different settings of food.
Dialogue: 0,0:01:45.62,0:01:52.80,Default,,0000,0000,0000,,So what do we do to have the refrigerator stay the same, but the freezer to be less cold?
Dialogue: 0,0:01:54.83,0:01:59.54,Default,,0000,0000,0000,,Well, the action is going to depend on the mental model that you have of the system:
Dialogue: 0,0:01:59.54,0:02:03.22,Default,,0000,0000,0000,,One reasonable model that you could have is that there are two cooling units,
Dialogue: 0,0:02:03.22,0:02:06.08,Default,,0000,0000,0000,,and there’s one dial that controls each of the units.
Dialogue: 0,0:02:06.08,0:02:08.42,Default,,0000,0000,0000,,And, in that case, what you would want to do
Dialogue: 0,0:02:08.42,0:02:13.47,Default,,0000,0000,0000,,is [to] figure out which of those is connected to the freezer and tweak that dial.
Dialogue: 0,0:02:13.47,0:02:18.48,Default,,0000,0000,0000,,[It] turns out that’s not actually how it works: That there’s only one cooling unit in this refrigerator,
Dialogue: 0,0:02:18.48,0:02:22.32,Default,,0000,0000,0000,,and then it has a splitter which controls the proportion of cold air
Dialogue: 0,0:02:22.32,0:02:26.31,Default,,0000,0000,0000,,that goes into either the refrigerator or the freezer.
Dialogue: 0,0:02:26.31,0:02:29.35,Default,,0000,0000,0000,,And so, if you’d like to be abe to change only one of the two chambers —
Dialogue: 0,0:02:29.35,0:02:32.09,Default,,0000,0000,0000,,in this case: make our freezer less cold —
Dialogue: 0,0:02:32.09,0:02:34.83,Default,,0000,0000,0000,,what you have to do is [to] move both of the dials —
Dialogue: 0,0:02:34.83,0:02:38.23,Default,,0000,0000,0000,,dial back the total amount of coldness going into the refrigerator,
Dialogue: 0,0:02:38.23,0:02:40.65,Default,,0000,0000,0000,,and then change the fraction
Dialogue: 0,0:02:40.65,0:02:45.76,Default,,0000,0000,0000,,so that the fridge still gets the cold air that it needs but the freezer is getting less.
Dialogue: 0,0:02:45.76,0:02:50.88,Default,,0000,0000,0000,,If a lot of users misunderstand the functions of these two dials and get them wrong,
Dialogue: 0,0:02:50.88,0:02:55.25,Default,,0000,0000,0000,,then I think it’s fair to say that this is a poor user interface.
Dialogue: 0,0:02:56.51,0:02:59.28,Default,,0000,0000,0000,,There’s a lot of ways that you could fix this.
Dialogue: 0,0:02:59.28,0:03:08.73,Default,,0000,0000,0000,,Pause the video and think of a few of how you might make this refrigerator interface better.
Dialogue: 0,0:03:08.73,0:03:11.16,Default,,0000,0000,0000,,Here’s a couple that I came up with:
Dialogue: 0,0:03:11.16,0:03:17.32,Default,,0000,0000,0000,,One is if the user believes that one dial controls the fridge and the other dial controls the freezer,
Dialogue: 0,0:03:17.32,0:03:20.16,Default,,0000,0000,0000,,you could have the functionality of the system work that way —
Dialogue: 0,0:03:20.16,0:03:24.11,Default,,0000,0000,0000,,that you’d have two blowers, one for each.
Dialogue: 0,0:03:24.11,0:03:29.12,Default,,0000,0000,0000,,You could also {\i1}simulate{\i0} two blowers, by having computation in the middle
Dialogue: 0,0:03:29.12,0:03:33.70,Default,,0000,0000,0000,,and still have the dials connected one for each of the two.
Dialogue: 0,0:03:33.70,0:03:36.62,Default,,0000,0000,0000,,Alternatively, if you {\i1}really{\i0} felt like it was essential
Dialogue: 0,0:03:36.62,0:03:43.14,Default,,0000,0000,0000,,to have the “total cold plus changing the fraction” model,
Dialogue: 0,0:03:43.14,0:03:48.10,Default,,0000,0000,0000,,which is probably not as good a user interface but might be needed for cost reasons,
Dialogue: 0,0:03:48.10,0:03:50.83,Default,,0000,0000,0000,,in that way you could think of a way to have
Dialogue: 0,0:03:50.83,0:03:58.46,Default,,0000,0000,0000,,a diagram or other kind of cue that would explain better what was going on rather than cryptic text.
Dialogue: 0,0:03:58.46,0:04:04.39,Default,,0000,0000,0000,,In all of those cases, the goal is for the user interface to beacon to the user
Dialogue: 0,0:04:04.39,0:04:10.17,Default,,0000,0000,0000,,what the mental model that they should think about the system with is.
Dialogue: 0,0:04:10.17,0:04:15.98,Default,,0000,0000,0000,,And, of course, as you interact with the system more, your model becomes more sophisticated.
Dialogue: 0,0:04:15.98,0:04:19.29,Default,,0000,0000,0000,,But there’s a big pitfall and a danger of being a designer:
Dialogue: 0,0:04:19.29,0:04:24.07,Default,,0000,0000,0000,,You’ve spent so much time with the system that you know it works under the hood
Dialogue: 0,0:04:24.07,0:04:26.99,Default,,0000,0000,0000,,and you how you imagine other people will think about it.
Dialogue: 0,0:04:26.99,0:04:32.56,Default,,0000,0000,0000,,But your expertise can be crippling: The mental model that you expect users to have —
Dialogue: 0,0:04:32.56,0:04:36.87,Default,,0000,0000,0000,,you expect it to be the same as yours — just often doesn’t pan out in practice.
Dialogue: 0,0:04:36.87,0:04:41.31,Default,,0000,0000,0000,,And that’s one of the reasons why it’s really important to get real people who are not the designers
Dialogue: 0,0:04:41.31,0:04:43.97,Default,,0000,0000,0000,,in front of interfaces as soon as possible —
Dialogue: 0,0:04:43.97,0:04:49.37,Default,,0000,0000,0000,,to help you discover those differences between your mental model and theirs.
Dialogue: 0,0:04:49.37,0:04:53.86,Default,,0000,0000,0000,,And the benefits of aligning the user and designer mental models are obvious:
Dialogue: 0,0:04:53.86,0:04:57.75,Default,,0000,0000,0000,,Because when you have this mismatch, that can often lead to slow performance,
Dialogue: 0,0:04:57.75,0:05:02.09,Default,,0000,0000,0000,,or errors, and frustration on the part of the user.
Dialogue: 0,0:05:02.09,0:05:06.09,Default,,0000,0000,0000,,Where do these mental models come from? Well, that’s a fascinating question,
Dialogue: 0,0:05:06.09,0:05:11.06,Default,,0000,0000,0000,,and one that deserves a longer answer than I can offer in this short video.
Dialogue: 0,0:05:11.06,0:05:14.35,Default,,0000,0000,0000,,But I can say a few things to get you started:
Dialogue: 0,0:05:14.35,0:05:17.82,Default,,0000,0000,0000,,The first is that people reason about new interfaces
Dialogue: 0,0:05:17.82,0:05:21.64,Default,,0000,0000,0000,,by analogy to old interfaces that they’re more familiar with.
Dialogue: 0,0:05:21.64,0:05:26.21,Default,,0000,0000,0000,,And when can leverage that — when you can figure out what people are familiar with —
Dialogue: 0,0:05:26.21,0:05:29.97,Default,,0000,0000,0000,,and use those metaphors intentionally in the construction of new interfaces,
Dialogue: 0,0:05:29.97,0:05:32.20,Default,,0000,0000,0000,,you’ll often be really successful.
Dialogue: 0,0:05:32.20,0:05:36.83,Default,,0000,0000,0000,,So, for example, if you can say that a word processor is like a typewriter,
Dialogue: 0,0:05:36.83,0:05:43.65,Default,,0000,0000,0000,,then people will transfer their believes and skills with the typewriter over to the new word processor.
Dialogue: 0,0:05:43.65,0:05:49.01,Default,,0000,0000,0000,,The models that we build that guide our action: We have about our behaviour, of other people’s,
Dialogue: 0,0:05:49.01,0:05:54.17,Default,,0000,0000,0000,,of objects, of software — really anything and anybody that we interact with.
Dialogue: 0,0:05:54.17,0:05:57.51,Default,,0000,0000,0000,,But that’s not to say that everything is tidy and organized upstairs:
Dialogue: 0,0:05:57.51,0:06:02.54,Default,,0000,0000,0000,,Our mental models are incomplete; they’re inconsistent; they change over time;
Dialogue: 0,0:06:02.54,0:06:05.60,Default,,0000,0000,0000,,and they’re often rife with superstition.
Dialogue: 0,0:06:05.60,0:06:07.86,Default,,0000,0000,0000,,The second thing that I’d like to talk about today
Dialogue: 0,0:06:07.86,0:06:13.17,Default,,0000,0000,0000,,is two important different kinds of errors that are based on the user’s mental model.
Dialogue: 0,0:06:13.96,0:06:19.16,Default,,0000,0000,0000,,The second thing that I’d like to do today is to distinguish two important categories of errors
Dialogue: 0,0:06:19.16,0:06:25.90,Default,,0000,0000,0000,,that are based on differences in what the user’s mental model is about what they believe.
Dialogue: 0,0:06:25.90,0:06:28.49,Default,,0000,0000,0000,,The first category is a slip.
Dialogue: 0,0:06:28.49,0:06:37.43,Default,,0000,0000,0000,,With a slip, you have the right model of how a system works, but you just accidentally do the wrong thing.
Dialogue: 0,0:06:37.43,0:06:47.44,Default,,0000,0000,0000,,So, if I go to reach for one button and press another — just by a motor error — that would be a slip..
Dialogue: 0,0:06:47.44,0:06:52.82,Default,,0000,0000,0000,,On the other hand, a mistake is when I do what I intend to do,
Dialogue: 0,0:06:52.82,0:06:57.29,Default,,0000,0000,0000,,but I have the wrong model of what I ought to do.
Dialogue: 0,0:06:57.29,0:07:02.89,Default,,0000,0000,0000,,So, if I’m driving, and I think that I ought to take this highway exit to get [to] where I need to go,
Dialogue: 0,0:07:02.89,0:07:09.18,Default,,0000,0000,0000,,and I take it exactly as I intend to, but I was wrong in my belief, that would be a mistake.
Dialogue: 0,0:07:09.18,0:07:16.11,Default,,0000,0000,0000,,And, as a designer, you’ll correct these two kinds of errors — or prevent them — in your design differently.
Dialogue: 0,0:07:16.11,0:07:20.98,Default,,0000,0000,0000,,Slips you’ll most often try to prevent by improving the ergonomics
Dialogue: 0,0:07:20.98,0:07:23.67,Default,,0000,0000,0000,,or visual design of the user interface —
Dialogue: 0,0:07:23.67,0:07:26.82,Default,,0000,0000,0000,,spread things out so it’s less likely that you’ll hit the wrong thing;
Dialogue: 0,0:07:26.82,0:07:29.02,Default,,0000,0000,0000,,make targets bigger.
Dialogue: 0,0:07:29.02,0:07:33.50,Default,,0000,0000,0000,,With mistakes, on the other hand, what you’ll need to do is [to] provide better feedback,
Dialogue: 0,0:07:33.50,0:07:36.04,Default,,0000,0000,0000,,or make clear what the options are.
Dialogue: 0,0:07:36.04,0:07:38.44,Default,,0000,0000,0000,,So, limit the number of mistakes that you [could] make.
Dialogue: 0,0:07:38.44,0:07:43.85,Default,,0000,0000,0000,,You’ll want to improve the user’s ability to perceive the affordances of your software:
Dialogue: 0,0:07:43.85,0:07:47.82,Default,,0000,0000,0000,,Make it clear to them what is possible to do.
Dialogue: 0,0:07:47.82,0:07:51.14,Default,,0000,0000,0000,,Here we have an interface that led to a lot of user errors.
Dialogue: 0,0:07:51.14,0:07:57.32,Default,,0000,0000,0000,,This is a ballot from Palm Beach County, Florida during the 2000 presidential election in the US.
Dialogue: 0,0:07:57.32,0:07:59.73,Default,,0000,0000,0000,,There were two major party candidates —
Dialogue: 0,0:07:59.73,0:08:04.73,Default,,0000,0000,0000,,the Republican candidate George Bush and the Democratic candidate Al Gore.
Dialogue: 0,0:08:04.73,0:08:08.46,Default,,0000,0000,0000,,Across the nation they were, overall, running neck-in-neck.
Dialogue: 0,0:08:08.46,0:08:14.22,Default,,0000,0000,0000,,There were also eight other candidates, to each gathered a smaller fraction of the vote.
Dialogue: 0,0:08:14.22,0:08:20.92,Default,,0000,0000,0000,,A user’s vote was recorded by a hole being punched out along the centreline of the ballot.
Dialogue: 0,0:08:20.92,0:08:23.80,Default,,0000,0000,0000,,It appears that, due to bad user interface design,
Dialogue: 0,0:08:23.80,0:08:27.34,Default,,0000,0000,0000,,people who intended to vote for one of the candidates, Al Gore,
Dialogue: 0,0:08:27.34,0:08:36.35,Default,,0000,0000,0000,,instead, accidentally pressed the hole corresponding to a different candidate, Pat Buchanan.
Dialogue: 0,0:08:36.35,0:08:41.52,Default,,0000,0000,0000,,While we’ll never know for sure, the data suggested that this is probably the case.
Dialogue: 0,0:08:41.52,0:08:47.07,Default,,0000,0000,0000,,So, the people who vvoted in Palm Beach County using this ballot style,
Dialogue: 0,0:08:47.07,0:08:52.52,Default,,0000,0000,0000,,about 0.85% of the votes were for Pat Buchanan.
Dialogue: 0,0:08:52.52,0:08:56.81,Default,,0000,0000,0000,,However, people who voted absentee, using a different style of ballot,
Dialogue: 0,0:08:56.81,0:09:00.29,Default,,0000,0000,0000,,had a much lower rate of votes for Pat Buchanan,
Dialogue: 0,0:09:00.29,0:09:07.50,Default,,0000,0000,0000,,and the reason appears to be that this hole in the middle right here was ambiguous —
Dialogue: 0,0:09:07.50,0:09:13.13,Default,,0000,0000,0000,,Yes, there’s an arrow pointing to it from the right, but it kind of lines up to the spot on the left.
Dialogue: 0,0:09:13.13,0:09:15.67,Default,,0000,0000,0000,,So, it appears that for about 0.6% of voters,
Dialogue: 0,0:09:15.67,0:09:21.84,Default,,0000,0000,0000,,they thought that that second hole corresponded to Al Gore rather than Pat Buchanan.
Dialogue: 0,0:09:21.84,0:09:27.09,Default,,0000,0000,0000,,And the question for you is: Is this a slip? or is this a mistake?
Dialogue: 0,0:09:27.09,0:09:30.20,Default,,0000,0000,0000,,These erroneous votes are the result of a mistake,
Dialogue: 0,0:09:30.20,0:09:34.97,Default,,0000,0000,0000,,because voters performed the manual operation that they intended to perform —
Dialogue: 0,0:09:34.97,0:09:37.48,Default,,0000,0000,0000,,punching that second hole —
Dialogue: 0,0:09:37.48,0:09:43.47,Default,,0000,0000,0000,,however, they had the wrong mental model about what punching that second hole meant.
Dialogue: 0,0:09:43.47,0:09:47.21,Default,,0000,0000,0000,,WIth better user interface design, it could have been clear
Dialogue: 0,0:09:47.21,0:09:54.34,Default,,0000,0000,0000,,which of these was the hole that corresponded to a Democratic candidate versus the Reform candidate.
Dialogue: 0,0:09:54.34,0:09:59.86,Default,,0000,0000,0000,,Another important lesson to learn from the butterfly ballot problem is that of consistency:
Dialogue: 0,0:09:59.86,0:10:07.31,Default,,0000,0000,0000,,Whenever we reuse designs that are already successful, we are less likely to make accidental mistakes.
Dialogue: 0,0:10:07.31,0:10:11.12,Default,,0000,0000,0000,,By contrast, as happens with a lot of voting systems,
Dialogue: 0,0:10:11.12,0:10:14.02,Default,,0000,0000,0000,,when every county makes their own voting system
Dialogue: 0,0:10:14.02,0:10:18.03,Default,,0000,0000,0000,,— or at least there’s broad diversity in the voting systems used —
Dialogue: 0,0:10:18.03,0:10:22.39,Default,,0000,0000,0000,,it’s much more likely that usability bugs will crop up.
Dialogue: 0,0:10:22.39,0:10:27.88,Default,,0000,0000,0000,,And so one way that we could fix this would be to have a nationwide standard voting system
Dialogue: 0,0:10:27.88,0:10:31.36,Default,,0000,0000,0000,,where everybody votes using the same user interface.
Dialogue: 0,0:10:31.36,0:10:38.23,Default,,0000,0000,0000,,One appealing option for a nationwide voting system would be to use electronic voting.
Dialogue: 0,0:10:38.23,0:10:43.02,Default,,0000,0000,0000,,If we were to build a better user interface for voting, what would it be?
Dialogue: 0,0:10:43.02,0:10:45.97,Default,,0000,0000,0000,,Well, given that we’re in a computer science class,
Dialogue: 0,0:10:45.97,0:10:51.36,Default,,0000,0000,0000,,one natural suggestion to offer up would be electronic voting.
Dialogue: 0,0:10:51.36,0:10:55.17,Default,,0000,0000,0000,,And electronic voting certainly has some very clear appeals:
Dialogue: 0,0:10:55.17,0:11:00.34,Default,,0000,0000,0000,,For example, it is much easier to internationalize to many different languages;
Dialogue: 0,0:11:00.34,0:11:03.58,Default,,0000,0000,0000,,You can have pictures of candidates to make things clear;
Dialogue: 0,0:11:03.58,0:11:07.05,Default,,0000,0000,0000,,You can have a touch screen so that you have direct manipulation.
Dialogue: 0,0:11:07.05,0:11:11.88,Default,,0000,0000,0000,,All of these are important and good advantages to electronic voting.
Dialogue: 0,0:11:11.88,0:11:15.77,Default,,0000,0000,0000,,However, as David Dill in the Verified Voting Foundation point[s] out,
Dialogue: 0,0:11:15.77,0:11:18.55,Default,,0000,0000,0000,,there’s one major problem with electronic voting:
Dialogue: 0,0:11:18.55,0:11:23.53,Default,,0000,0000,0000,,How do you know that the machine recorded the vote that you intended?
Dialogue: 0,0:11:23.53,0:11:28.32,Default,,0000,0000,0000,,And their proposed solution to this user interface problem is really clever:
Dialogue: 0,0:11:28.32,0:11:36.59,Default,,0000,0000,0000,,What they proposed is that the machine print out a paper receipt of the vote that you cast;
Dialogue: 0,0:11:36.59,0:11:41.92,Default,,0000,0000,0000,,however, you don’t get to take the receipt with you, because that would run the risk of vote-buying.
Dialogue: 0,0:11:41.92,0:11:47.31,Default,,0000,0000,0000,,Instead, that receipt falls behind a glass or plastic clear pane,
Dialogue: 0,0:11:47.31,0:11:52.64,Default,,0000,0000,0000,,and so you can see it being printed out, and you can see it go into a bin,
Dialogue: 0,0:11:52.64,0:11:55.94,Default,,0000,0000,0000,,and it’s stored there for the purposes of recount.
Dialogue: 0,0:11:55.94,0:12:00.99,Default,,0000,0000,0000,,That way, you can always manually verify the computer-generated tally.
Dialogue: 0,0:12:00.99,0:12:06.50,Default,,0000,0000,0000,,The butterfly ballot costs problems because the representation was really confusing —
Dialogue: 0,0:12:06.50,0:12:10.60,Default,,0000,0000,0000,,What lined up with what was hard to figure out.
Dialogue: 0,0:12:10.60,0:12:13.49,Default,,0000,0000,0000,,Here’s an example that’s much better:
Dialogue: 0,0:12:13.49,0:12:18.67,Default,,0000,0000,0000,,This is a seat user interface for an automobile that employs a “world in miniature” strategy.
Dialogue: 0,0:12:18.67,0:12:22.27,Default,,0000,0000,0000,,It offers controls for manipulating parts of the seat,
Dialogue: 0,0:12:22.27,0:12:26.12,Default,,0000,0000,0000,,and the interface for doing that is a miniature seat itself.
Dialogue: 0,0:12:26.12,0:12:33.23,Default,,0000,0000,0000,,So, if you’d like to move the headrest back, you can move the miniature headrest back.
Dialogue: 0,0:12:33.23,0:12:38.93,Default,,0000,0000,0000,,By having this clear mapping, users are much less likely to make errors.
Dialogue: 0,0:12:38.93,0:12:44.05,Default,,0000,0000,0000,,So far, we’ve seen how direct manipulation enables users to behave with much more expertise
Dialogue: 0,0:12:44.05,0:12:47.68,Default,,0000,0000,0000,,by leveraging familiar real-world metaphors.
Dialogue: 0,0:12:47.68,0:12:53.29,Default,,0000,0000,0000,,This “directness in real-world” metaphor — like “to move a slider you move a slider” —
Dialogue: 0,0:12:53.29,0:12:59.46,Default,,0000,0000,0000,,helps give users a good idea of how each object works and how to control it.
Dialogue: 0,0:12:59.46,0:13:05.39,Default,,0000,0000,0000,,And also, the interface’s physical form discloses what functionality it provides.
Dialogue: 0,0:13:05.39,0:13:08.94,Default,,0000,0000,0000,,So this is all great, right? Well, here’s the challenge:
Dialogue: 0,0:13:08.94,0:13:14.93,Default,,0000,0000,0000,,The reason that we have technology and software as opposed to the real world that we used to have
Dialogue: 0,0:13:14.93,0:13:17.73,Default,,0000,0000,0000,,is that we want to be able to do something new!
Dialogue: 0,0:13:17.73,0:13:21.75,Default,,0000,0000,0000,,So, the reason that have a digital slider as opposed to a physical slider
Dialogue: 0,0:13:21.75,0:13:27.41,Default,,0000,0000,0000,,is that, at least somewhere in the system, there’s some kind of new functionality being offered.
Dialogue: 0,0:13:27.43,0:13:29.59,Default,,0000,0000,0000,,And so, as Jonathan Grudin points out,
Dialogue: 0,0:13:29.59,0:13:33.73,Default,,0000,0000,0000,,if technology is providing an advantage — if there is this new functionality —
Dialogue: 0,0:13:33.73,0:13:38.51,Default,,0000,0000,0000,,at some point, the correspondance to the real world has to break down.
Dialogue: 0,0:13:39.09,0:13:46.22,Default,,0000,0000,0000,,So this gap between the new technology and the current practice is necessarily going to be there.
Dialogue: 0,0:13:46.22,0:13:51.52,Default,,0000,0000,0000,,But your goal, as a designer, is to minimize this distance as much as possible.
Dialogue: 0,0:13:51.84,0:13:54.33,Default,,0000,0000,0000,,One of my favourite examples of a user interface
Dialogue: 0,0:13:54.33,0:14:00.89,Default,,0000,0000,0000,,that has this property of offering new functionality but minimizing the distance to current practice
Dialogue: 0,0:14:00.89,0:14:04.10,Default,,0000,0000,0000,,is the system for DJ’s called “Final Scratch.”
Dialogue: 0,0:14:04.10,0:14:06.68,Default,,0000,0000,0000,,This is a photograph that [inaudible] Hartman took,
Dialogue: 0,0:14:06.68,0:14:11.86,Default,,0000,0000,0000,,and what you see here is that the DJ is operating two turntables,
Dialogue: 0,0:14:11.86,0:14:15.22,Default,,0000,0000,0000,,much as one would do with normal vinyl.
Dialogue: 0,0:14:15.22,0:14:21.07,Default,,0000,0000,0000,,The difference is that this is special vinyl: It has a code on the record,
Dialogue: 0,0:14:21.07,0:14:28.47,Default,,0000,0000,0000,,and that code is being used to control a Linux system that you see on the laptop off on the left.
Dialogue: 0,0:14:28.47,0:14:33.07,Default,,0000,0000,0000,,And so, as opposed to the record playing music that’s piped out to the speakers,
Dialogue: 0,0:14:33.07,0:14:38.55,Default,,0000,0000,0000,,the record plays a code to the computer, and the computer plays the music to the speakers.
Dialogue: 0,0:14:39.55,0:14:43.50,Default,,0000,0000,0000,,So why is this a good idea? Well, there’s a couple of reasons:
Dialogue: 0,0:14:43.50,0:14:48.48,Default,,0000,0000,0000,,One, it means you can play anything, not just something that’s been produced into vinyl.
Dialogue: 0,0:14:48.48,0:14:52.41,Default,,0000,0000,0000,,Another one is that you only have to carry two record[s], not 200.
Dialogue: 0,0:14:52.41,0:14:55.49,Default,,0000,0000,0000,,And, more generally, it gives you all of the benefits of digital music
Dialogue: 0,0:14:55.49,0:14:58.85,Default,,0000,0000,0000,,like, you can produce it in the morning and play it that evening —
Dialogue: 0,0:14:58.85,0:15:02.44,Default,,0000,0000,0000,,you don’t have to wait several months for production to happen.
Dialogue: 0,0:15:02.44,0:15:04.78,Default,,0000,0000,0000,,When used well, physical interfaces
Dialogue: 0,0:15:04.78,0:15:10.28,Default,,0000,0000,0000,,that leverage people’s dexterity, manual abilities, and intuitions about the physical world
Dialogue: 0,0:15:10.28,0:15:12.96,Default,,0000,0000,0000,,can be incredibly powerful.
Dialogue: 0,0:15:12.96,0:15:16.55,Default,,0000,0000,0000,,These physical interfaces can also yield an experience that’s more fun to watch,
Dialogue: 0,0:15:16.55,0:15:19.97,Default,,0000,0000,0000,,which, if you’re a DJ, is really important.
Dialogue: 0,0:15:19.97,0:15:22.00,Default,,0000,0000,0000,,And, finally, here’s some resources
Dialogue: 0,0:15:22.00,0:15:29.37,Default,,0000,0000,0000,,if you’d like to learn about mental models, errors, and butterfly ballots.