NAK

Created: 2003.11.10 | Last updated: 2020.10.11

One of my pet peeves is NAK systems "Negative AcKnowledgement" systems. Whenever I try to create a system or a policy, I like to use PAK "Positive AcKnowledgement"

Some examples of NAK systems that exist in real life:

  • Street walk light button - How many times DO you have to hit the Red button anyway ? And how hard? Do you keep hitting it until it eventually turns to Walk or, do you hit it once and then patiently wait to see if turns to Walk when the cars go and, if it doesn't, you just walk on the "don't walk" light? When I was in elementary school (grade 3 I believe) we had a guest who made a big deal about "only hit the button once" - something about wearing the buttons out. At that time I thought it was a stupid design, I still think it is a stupid design, especially since the cross walk button near my place DIDN'T work reliably and I had already learned to hit the button 3 times hard. Fortunately by that age I had learned to not blindly trust adults so I ignored that adult - I still hit them hard, the button, not the adult, to make sure they register, and often hit them twice, just to make sure. Enough times in my life when I only hit it once, it didn't register. Update 2020: I do notice that a lot of these buttons now beep or light up when you hit them, but I was watching at one corner where I was waiting for something, fascinated that the older people hit it 2 or 3 times despite it beeping, but younger kids (in their 30's) only hit it once. It appears that the older ones are so used to those crosswalk buttons ignoring them that they don't believe it even when it beeps acknowledgment, the government TRAINED them to not trust those buttons, and the younger kids are so trusting of the beep that they only hit it once. Or maybe the older people can't hear the button beeping - regardless, they have clearly been trained by NAK systems to not trust just hitting it once, and definitely wouldn't think to just 'touch' it.

    • When I went home after the City lady had instructed us sternly to NOT hit her button on the crosswalk more than once ... I told my parents about it (I was 8 years old) and told them WHY I had picked '3 times hard' as my action. My parents agreed that I had picked a reasonable response and that, because they wanted me to obey the law and only cross when it says 'walk', that they approved of my '3 times hard' practice and that I could politely ignore the city lady.

    • I should also mention that the city lady did acknowledge that she knew the buttons didn't always work, but that hitting them multiple times would just cause them to fail faster. What she didn't understand is, as an 8 year old - I needed to get across the street! And the rate the buttons wear out had no value to me if I couldn't cross the street because her buttons were defective, and it wasn't my fault that she had installed a NAK. Noting that even back then, there were LED light buttons, and obviously there was some sort of electric signal getting to/from that button for it to register the request to cross. So ... to save money, she (or someone), decided to put in a system that she claimed would wear out much sooner under practical use!

  • Closing the door in an elevator - Why do the have a door close button anyway? I've NEVER come across an elevator that closes the door when I press the button. I think some psychopathic maniac put the buttons in just so they could watch people fruitlessly pushing it. And yes, when I get in almost any elevator I haven't been in before, I hit the close button just to see if this one has a close button that does something.

    • the only time I see elevator close is in movies when they want the protagonist to get away from the bad guy, or for the bad guy to get away from the protagonist.
  • Like choosing a floor in an elevator - If the light doesn't come on - should you hit it harder or just hit it repeatedly until it stops on the floor you wanted? Most people pick to hit it hard and repeatedly. If you don't believe me - look at the buttons on elevators that do light up, then look at the ones that don't light up. If they are about the same age, you will see that the ones that don't light up have been much more aggressively hit, scraped and beaten than the ones that light up to say "Yes, I heard you." It almost seems that we don't even care if it takes us to the correct floor - as long as it appears to be paying attention! Update 2020: I noticed this on two particular elevators where some buttons light up and others, on the same elevator, did not. The ones that did not light up where very badly worn - and I saw nothing in the directory that indicated that 10x's as many people would be stopping on those floors.

  • Like saying "I'll call if I get lost" then after hanging up realizing you forgot that they called you, and you forgot to ask them for their phone number. If you said you'd call when you got there, maybe they would phone back to see if you had problems. Update 2020: by now, for most people, your cell phone plan will tell you who the caller was or at least the number that called, so if they call you, you have their number.

  • Or "Meet me at (some location an hour from their house) unless I call you back" - then, when you can't make it, you don't call them because (as above) you forgot to ask for their phone number or whatever emergency happened, you didn't have time to call them to tell them you wouldn't be able to make the appointment. If not making it is a realistic possibility, instead say "I'll call you by such and such time if I can still make it."

  • Or like the important email I received that actually said "Please inform me immediately if you do not receive this message." The proper thing to say would be: reply when you receive this" and then resend to anyone that doesn't reply - and if they still don't reply, contact them through some other medium. I've received about a dozen of these through the years and I'm always tempted to reply "Thank you, no I did not receive the email below."

For developers only:

  • Of course, the whole Internet, including email, is predicated along a NAK design. Files (packets) are sent out but the receiver doesn't acknowledge receipt. (And yes, there are systems that overcome this - but I'm talking about the fundamental design, not specific people who, like me, believe in PAK and protocols, like our software and some others that implement PAK overtop of the internet NAK.)

OK, now here is a funny joke: If you don't understand it, read everything above, then read the line below out loud. If you are English as a Second Language (ESL) stop reading the paragraph before this one ;)

Do you have the NAK? Did you get the NAK?