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Proximity in Design: Why I Can’t Use My Car’s A/C


I’m always fumbling with the A/C controls in my car. My daily commute is in hot, sunny Southern California, home of the courteous freeway driver. I can’t afford to take my eyes off the road for too long to find the control I’m looking for. Half of the time when I’m trying to adjust the temperature, I end up blowing my beard off because I’ve spun the wrong dial. If my wife’s in the car with me, I usually resort to asking her to do it for me.

My Car's A/C Controls1

There’s a simple design principle that, had it been given greater attention, could have made this needlessly confusing interface much easier to use: proximity.

Dude, Which One’s My Car? Link

The human brain works by processing visual (and aural) input that occurs in proximity, either spatially or temporally. It then assembles this information into recognizable patterns and assigns meaning to it.

When I’m searching for my car in the parking lot, my eyes take in the size, shape, color and location of the cars I see (input). My brain then determines that I’m seeing an SUV, a truck, and 27 Honda Civics (patterns). Finally my brain tells me which vehicles are not mine until I “recognize” the pattern that is my car (meaning).

Tyrannosaur Attack Link

This pattern-making ability also causes our brains to assign meaning and create relationships even when they may not actually exist. In the film Jurassic Park2, a Tyrannosaurus Rex grabs a smaller dinosaur in its teeth and shakes it around, killing it. The sound of this attack could not be recorded while shooting the scene (dinosaurs are, much to the chagrin of every school-age boy, still very much extinct). And so sound engineer Gary Rydstrom3 set out to create a sound that would convincingly sell the on-screen images.

Tyrannosaur Attacking Prey4

So what sound recording did Rydstrom use to emulate a seven-ton predator ripping through the flesh of its prey? None other than his own Russell Terrier, Buster, playing with a rope toy5! If you watch the scene knowing this, the effect is rather cheesy and unbelievable. But for the unsuspecting viewer, the brain willingly interprets the simultaneity of visual and aural inputs as indicating relationship and meaning. We see a dinosaur eating and we hear a simultaneous sound. Our brain tells us “this is the sight and sound of a T-Rex eating its prey.”

Proximity Without Purpose Link

In my car, as I’m trying to determine which button to press or dial to spin, my brain is analyzing the proximity of these various controls to discern a pattern which will help me make sense of their functions.

Let’s take a closer look:

A/C Controls with Function Labels6
Top Row (left to right): Air temperature, front window defrost, fan speed. 2nd Row: Fan off, fan mode (chest, feet, etc), A/C power. Bottom Row: Re-circulate, rear defrost, rear (back seat) fan, outside temperature indicator.

The controls are a combination of push buttons and dials that affects two basic functions: fan speed and air temperature. Each of the three control groups is comprised of one dial and one or two buttons. My pattern-seeking brain assumes that the buttons and dials are placed and grouped in a manner that has meaning. Unfortunately for my brain, in this case they aren’t.

Here’s a common two-step process I perform to cool down my car: I first turn on the A/C (step one) and then adjust the temperature (step two). To achieve this goal, I must:

  1. press the right bottom button and
  2. spin the left dial.

However, while avoiding collisions with tailgaters and cell-phone talkers, I often perform the wrong sequence. I:

  1. press the right bottom button (1, correct) and
  2. spin the same dial (2, incorrect).

By spinning the wrong dial (accidentally changing the fan speed) I end up with a hot jet blast to the face.

Reinforce Relationships Link

A very simple reorganization of my car’s controls would reinforce the relationships between controls and make the entire system easier to use. By placing all the controls that adjust fan speed, and all those that adjust air temperature close together, the position of each control will have assigned greater meaning and users’ overall mental effort will be decreased. The sum of these two factors (increased meaning and decreased mental effort) will result in greater user success.

Optimized A/C Control Layout7
Controls are grouped by function to decrease mental effort and increase meaning.

In this revised layout, the controls’ proximity to the others reinforces their relationships. The left control group can be spun to adjust fan speed or pressed to turn the fan completely off. The right control group can be spun to adjust air temperature or pressed to further adjust the temperature (top button for automatic temperature, bottom button for A/C).

With these changes, my two-step process for cooling down the car is simplified. Step one is to turn on the A/C by pressing the bottom right button. Step two is to adjust the temperature by spinning the same dial.

Keeping Our Beards On Link

Understanding our brains’ fondness for creating meaning and patterns through proximity will help us create more intuitive interfaces and designs. If we take time to think about the way elements are positioned in relation to one each other, our interfaces will seem easier and more natural to our users. And nobody’s beard will get blown off.

Further Reading Link

(ik) (vf)

Footnotes Link

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David Cole (@davidrcole) craves simplicity. At home, David is a foster dad to two wonderful preschoolers. At work, he navigates complex business needs to craft simple interfaces. David is a Senior UX/UI Designer in San Diego, CA.

  1. 1

    Joel Sutherland

    April 26, 2011 4:55 am

    I think you’re mostly polishing a turd here. The circular buttons whose spinning is sometimes meaningful is such a bad idea that I don’t know if any improvement will help the fundamental issue.

  2. 2

    Himanshu Kapoor

    April 26, 2011 4:26 am

    Car controls are discussed as typical case in most usability books (remember, The design of Everyday Things by Don Norman). Your article is a good refresher. I do have similar problem with my car stereo (Sony make), where I have to read a manual to adjust various functions. However, AC control in both of my cars (Suzuki Alto and Hyundai i10) are extremely simple and can be operated even without looking at the dashboard. I sympathize with you as your Car AC controls looks quite stupid.

  3. 3

    Very nice co-relation… good read… :D

  4. 4

    Well, get a car with controls on steering wheel and there you go, just look at the top control display and you can follow the traffic while controling the airco. In few days you’ll know how many left/right presses or up/down controls are needed in order to reach every control, even without looking at the display and there you go :) A Japanese replacement: Mazda6. Try it.

    Good article, though :)

  5. 5

    It hurt my head just reading about using those controls.

  6. 6

    I think your premise about the buttons is wrong from a usability standpoint. How often do you change the air speed as compared to the temperature? Generally, the temperature is sent once (coldest/hottest), and you adjust fan speed to suit. In this case, the current layout is ok – turn on, adjust fan speed on same dial, so no need to move your hand at all. However, it would have been better to put it on the driver side, not the passenger side (but maybe the layout was made from Japan/British roads in mind). Further, what about muscle memory? I can understand making this mistake a few times, but eventually you will remember which is which, even without viewing I think. My car doesn’t have a great layout, either, but after a few times you learn to adjust without looking.

    Also completely agree with Joel – 3 circular buttons right next to each other, each the same diameter, same extension from the face plate, no visible knubs to distinguish them, etc – just asking for problems.

    • 7

      I do agree with the “muscle memory” behaviour. Even the interface is incorrect, the brain will learn from mistakes and will adapt to correct these after several attempts. It would be better if the article included some website examples about proximity design within the article instead inside the Further Reading section.

  7. 8

    This would also be a good example for localization. I expect you (in southern california) never use the front window blowers, right? Then why is it placed in the middle just as big as the a/c button. In my case: I would use the a/c and front blower just as much (during summer of winter in holland). In Alaska the a/c will never be used…

    In your case (or any case) climate control would be very convenient… just set a temperature and leave it.

    • 9

      Jeroen – that’s a very cool idea, but i can explain why: cost.
      It’s cheaper to manufacture more of the same, not more things that are different. That’s the reason all ATMs have braille – it’d be expensive to make 99 that didn’t and one that required new machines and another assembly line (source: Robert H Frank’s The Economic Naturalist)

      That applies to web, too. It takes more time to localize an interface to a given set of users – either based on authentication or IP address. And that’s why “out of the box” is cheaper, and crappier.

  8. 10

    Interesting read. Thanks :)

  9. 11

    Why don’t you leave the A/C on at your most comfortable setting? I have mine set at 19 degrees (Celsius that is), which is comfortable for all outside temperatures.
    You may use a little bit more fuel, but you keep your A/C in better shape thus reducing maintenance costs..

    In the end you’ll save a lot of money (repairing the A/C isn’t exactly cheap) and you can keep your eyes on the road, where they belong :)

    • 12

      Jorick, you’re confusing the author’s manual AC system with automatic climate control. Climate control allows the driver to set a cabin temperature (usually shown in degrees on an LED/LCD) and the car will automatically blow hot or cold air to reach this.

      With the manual system you need to set the temperature of the blown air. So in summer you’ll want it set to cold, and in winter to hot. As the system has no thermostat it can’t adjust itself so the driver needs to alter it depending on the weather.

      • 13

        You’re right. I stand corrected ;)

        I assumed the author’s car was equipped with an ACC because it has an Auto-mode on the temperature dial, which is not often found on manual A/C’s.

  10. 14

    it’s a mazda, isn’t it? the controls pretty much look the same as in my ’04 mazda 3. ;)

  11. 15

    Sorry for the off-topic, but what car is that?

  12. 16

    Good read, and totally agree wid u :)

  13. 17

    But you don’t have a beard! However, a good illustrative example which even I can follow.

  14. 18

    I hope people at BMW are reading this. iDrive still needs a lot of work!

  15. 19

    I am so glad to have a Vibe, which has commonsensical controls; if I had to drive your car, I would have crashed by now.

  16. 20

    My Kia Rondo has a fantastic feature that makes this all moot: auto temperature control. With the “auto” feature turned off, I have a “mode” button that lets me select where the air is blowing from (face, feet, dash, etc), a fan speed dial, and a temperature dial (between 17 degrees celsius, and 32 degrees). With the auto feature turned on, the “mode” and “fan speed” options are ignored, and the car simply figures out what mode it needs to accomplish the temperature request.

    Then all I do is simply dial a temperature in half-degree increments. Almost year round, I can simply leave the temperature at 20 degrees. In the summer, the A/C will run to do that, in the winter, the heat will run. If the window is frosted over, it will automatically switch to defrost mode until the temperature is warm enough to switch back to feet. If I go into a heatwave and spin the dial down to the lowest setting, 17, it will blast the full A/C on me to cool me down. If I go up just half a degree to 17.5, it will cut everything back and circulate the air indirectly (rather than just blasting my face) to make the temperature right.

    99% of the time, I just dial a temperature, and within 30 seconds, the car is exactly the temperature I want. It’s luxury, I tell you… :)

    • 21

      That’s how the author’s works too, I’m sure, he just never read the manual, I surmise. Witness: the auto button on the left knob.

  17. 22

    Great article, thanks for the insight!

  18. 23

    Great, great, GREAT post.

    Good design should ALWAYS make things easier.

  19. 24

    I can’t believe you call SoCal hot. I chuckle. Try living in the South for a summer… then you’ll know hot.

    Nice post. I think that most instrument panels demonstrate terrible layout. I mean, just look at some of the turn-signal / wiper blade stalks that come off of the steering wheel. What a cluster.

  20. 25

    Joshua Schnable

    April 26, 2011 7:49 am

    I had a rental Mazda 5 this past weekend and experienced the same thing. Even stranger – this is a completely different layout than the Mazda 6 control panel.

    1 knob to control temp, 1 selection knob to select fan position, 1 selection knob to control fan speed. A separate button to turn A/C on and off. Why mess with something that’s worked for a long time. The knobs without icons or indicators (maybe there are indicators, but they are placed far away from the knob).

  21. 26

    Contrary to popular belief A/C != temperature control. It simply conditions the air. Combine it with a high temp and you can de-fog your windows like a champion (most cars kick on the A/C automatically when you enable the defrosting fans).

  22. 27

    Wow, wow!!! This is amazing! Incredible! Briliant! Great article!

    /* avoiding censorship */

  23. 28

    These controls look a lot like those of my 2010 Mazda 5. They just plain suck. They already sucked in the 2007 model, and Mazda managed to make matters even worse by randomly moving functions in the new series, nevermind muscle memory. I think about microwave ovens every time I need to adjust the settings (which is *daily*, here in Quebec).

    Your grouping would make a lot more sense. A pity Mazda engineers will never hear of this.

  24. 29

    In your redesign, you moved the most commonly used dial (the temperature dial) furthest from the driver, which is probably bad. Furthermore, in most vehicles with automatic climate control, you just need to leave the a/c button on and adjust the temperature. The hvac system will figure out whether it needs to run th e a/c compressor or not to get to your desired temperature.

    • 30

      Good points about proximity to the user. I was thinking primarily about controls’ proximity to one another. You’re right in saying that the most commonly used controls would be ideally placed closest to the driver!

    • 31

      Just because it’s the furthest from the driver doesn’t mean that’s true everywhere – remember that 1/3 of the world is right hand drive! (Although being the only mph country which has km/h on the speedo and being one of only two countries on the continent which drive on the left we get a fair bit of unique cockpit stuff anyway)

      Depending on the cockpit layout the easiest control to get to can be the furthest from the drive – for example my fan speed control (the one I use the most) is the furthest left (i.e. furthest from the driver) but this is no big deal as the hand spends a fair amount of the down there anyway changing gears. The least used control (position) happens to be nearest to the driver but also the hardest to access (then again being 1.93 tall in a small car does mean my legs foul the centre console at times).

      The best example is trying to control the entertainment system on a BMW from the drivers seat – a counter-intuitive dial/joystick you are expected to control with your left hand – no wonder motoring journos over here generally dislike it!

  25. 32

    Yes, I’m always surprised at how bad user interface design is in most car dashboards. Every time I rent a car it takes a solid 10-15 minutes to figure out how to use the heat/air and audio options, not to mention cruise control, lights, etc.. It seems like most car companies are just leaving the dashboard layout to the same engineers who do the programming behind the scenes. Hire a UX person!

  26. 33

    All good points and definitely a good rearrangement of controls. However, I think the original design is based on the perceived frequency of use. I would guess that the original designers figured you’re much more likely to turn on/off the fan and adjust the overall temperature, than turn on/off AC and adjust fan speed. Although with that in mind, the fact that AC/fan controls are on far right instead of middle doesn’t make sense, so it’s a bad design in any case. :)

  27. 34

    Good article, and you’d think that they would make things a lot easier. I’ll share my experience as some of the previous commenters have alluded to their specific car experiences.

    I drive one of those Honda Civics that you made a crack about (don’t worry no offense taken lol) and it is a 90’s model, and I find it to be one of the easiest climate controls I’ve experienced. Perhaps the years of owning the car has made it even easier for me, but I’ve never struggled with it. Everything is in it’s right place, and I can control it without taking my eyes off the road, plus I drive a manual transmission!

    The great thing about the controls is that there aren’t any spinning circles. As someone mentioned earlier, I think that they hinder accurate control. The Off-4 setting on my car seems accurate especially when you can feel the tension when sliding, and setting it into place. I’m also in freezing cold Canada, and it’s a small car, so I’m constantly playing with the controls because I either have a frozen car, a fogged up car, or a roasting bucket on wheels in the humidity of summer lol.

    Just my input!

  28. 35

    Really great article, simple way to explain the importance of proximity in design

  29. 36

    Do you think that you would use it or that you will still say it to your wife?

    But I agree – car controls are stupid in generally any car i have been using in my live and it is geting worse and worse as number of controls increasing. We will need someone like Apple to do it.

    BTW even your concept is far from optimal, but i understand that you wanted to keep the same number and type of controls. E.g. imo front/rear should be on the same button, Mode should be a switch or button per zone, if the second one cannot be spinned (as there are no arrows), it should be buttons etc.

    I like todays combining of everything using big screens (e.g. using ipad), where you select e.g. A/C and you will see kontextual a/c controls, then when you select navigation, you see navigation controls and map etc.

    P.S.: but i understand that car controls are just an example of design.

  30. 37

    So glad to see that I am not the only person who does this :-)


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