I think it's interesting the way Stack Overflow has garnered such a following.

I think that the success of Stack Overflow has a lot to do with how Stack Overflow is taking advantage of how people think in novel ways.

By awarding "Badges" and "Reputation", I believe that the Stack Overflow system takes advantage of people's natural hunting and gathering instincts as well as the desire of fame.

What other aspects of human nature and psychology do you feel that Stack Overflow successfully exploits to make people want to answer questions about programming?


6 Answers 6


Actually, the main psychological phenomenon underlying Stack Overflow (and numerous other sites with similar reputation/karma/badge/reward systems) is something that's been discussed on meta before: Intermittent Variable Reward. Although I think the "correct" term (or at least the one more commonly used) is simply intermittent reinforcement. Intermittent implies a schedule of some kind, and the schedule here is called Variable Ratio. Generally the whole thing is colloquially called random reinforcement, as it's a well-known technique.

Positive and negative reinforcement are obviously pretty basic concepts. When subjects respond correctly to a cue, you give them something they want. When they refuse or do something bad, you punish them either directly or indirectly (by taking away something they want).

What a lot of people don't realize is that with positive reinforcement, the conditioning doesn't really "stick" if you always give the reward. They'll keep doing what you want as long as you keep giving the reward (and as long as they still want it), but as soon as you take the reward away, they will stop. The only reason to perform the behaviour is to get the reward, so in their mind, there's no longer any reason to continue to cooperate. The technical term for this is extinction.

Switching to a variable ratio of reinforcement - meaning you give 1 "unit" of reward for every X responses, where X changes randomly after each reward - is one of the most effective forms of conditioning and almost universally used by animal trainers. It is highly resistant to extinction; because the subject never knows exactly when the next reward will be, they will continue to work for it almost indefinitely.

The result of this, particularly in humans, is addiction. People make up for the uncertainty of a reward with increased activity, hoping that it will get them "enough" of the reward.

Stack Overflow (and similarly-designed sites) stumbled upon this accidentally, or at least it would appear that way. Individually, the system of reinforcement appears to be continuous; you see a good answer, you upvote, you see a bad answer, you downvote. But when you look at the big picture, which includes:

  • Different users being online at different times;
  • Other questions competing for front-page space;
  • Differences in subject matter and technical knowledge among readers/voters;
  • Vote limits, voting incentives (electorate etc.) and other artificial stimuli;

...and so on - then what it all amounts to is one massive system of random reinforcement. Posting what you think is a good answer means you might get some reward for it. The emergent schedule is actually pretty similar to what's used in ordinary conditioning, usually dishing out a reward for every 1-10 responses. And of course, the size of the reward also varies; setting artificial, relatively difficult-to-reach targets like reputation caps help to cement the sense of proportion.

Perhaps going off on a tangent here, but I think it's interesting to add, if you switch to a reinforcement schedule that's random based on time and is not tied in any way whatsoever to the behaviour itself, you'll often see the phenomenon of superstition and cult-like behaviour. Think of rain dances, ritual sacrifices, even quack medicine - humans become obsessed with these because they sometimes seem to "work." Unlike animals, humans are able to form far more complex associations over much longer periods of time, and as a result tend to latch onto what they think is a pattern and interpret any future results as VI reinforcement. They're doing it right, they just have to keep at it a little longer!

I suppose we could have another long and tedious discussion about what makes the intangible reward of reputation/badges so attractive to members, but the truth is, it doesn't really matter what the reward is as long as it's measurable. Something as basic as a compliment works just fine. It's why people obsessively play RPGs; every now and then they get a level-up or something similar which communicates the concept, "you're awesome." Reputation and badges are really no different - they're little compliments, randomly given for some definition of positive behaviour.

There are many other psychological concepts you may witness within Stack Overflow - but most assuredly the one it takes advantage of is random reinforcement.

  • 19
    +1 so insightful it's spooky. I'm going to be more careful what I ask. Commented Jul 13, 2010 at 1:06
  • 5
    I like this answer so much I'm giving you 500 rep, just as soon as it lets me award this bounty. Put that in your random reinforcement pipe and smoke it! Excellent answer. Suddenly the compulsion some people have to play the lotto makes perfect sense, and their weird reliance on programs and tricks for selecting their numbers.
    – Pollyanna
    Commented Jun 9, 2011 at 16:41
  • 2
    This is a superb answer. However, I would also note that StackOverflow (whether intentionally or unintentionally) also uses a 'thinning' (increased interval) schedule of reinforcement for the badges/privileges. stackoverflow.com/help/privileges Compare with: Kahng, S., Iwata, B. A., DeLeon, I. G., & Wallace, M. D. (2000). A comparison of procedures for programming noncontingent reinforcement schedules. Journal of Applied Behavior Analysis, 33(2), 223–231. doi:10.1901/jaba.2000.33-223 ncbi.nlm.nih.gov/pmc/articles/PMC1284240/pdf/10885529.pdf
    – d-cubed
    Commented Apr 22, 2014 at 13:04
  • Is there a StackExchange forum for Applied Behavior Analysis (ABA)?
    – LN6595
    Commented Feb 2, 2015 at 20:59
  • Was there any forum system that hat similar rewarding system before SE?
    – Honey
    Commented Jan 7, 2021 at 12:31


alt text

Seriously, I think the number one thing Stack Overflow appeals to is addiction! I don't smoke, drink, gamble or anything else but, whenever I have a break or some time, I always wonder to myself how long has it been since I last logged on and/or is there anything I can do!

In all honestly, I do not care about reputation or badges - but at the same time, I do wonder to myself if I would be as active if they were not here.

I believe I have a great technical knowledge and Superuser gives me the chance to talk to/help others with problems and without it, I would just be going to waste! - (Anyone in the UK need a good MS engineer/IT Pro? Please email me! :) )

I think with me it is a "controlled" addiction (If such thing exists?) I have cut back recently due to work commitments, and can easily not visit for a while if I want - but if I am feeling a bit bored and or annoyed, I log in, help someone with a problem and then it actually makes me feel better!

  • 13
    +1 if only for that pic.
    – Randolpho
    Commented Jul 12, 2010 at 20:48
  • 7
    +1 only for the clever sticker
    – rlb.usa
    Commented Jul 13, 2010 at 16:09

First off, I think many answers to this question are provided tangentially in this question:

Why do programmers help each other without pay?

I have a slight quibble with your opinion of badges and rep. I would argue that hunting/gathering instincts and desire for fame are not the main drivers there, though they are involved. Instead, I believe that rep and especially badges satisfy the desire to succeed at things and complete objectives. They're really quite similar to how modern video games offer rewards for all kinds of tasks (PS3 Trophies, 360 Achievements/Gamerscore, Kongregate Badges/Level, &c.). Carnegie Mellon professor Jesse Schell gave a nice presentation about how "gamification" is a rising trend in many aspects of our lives. See the TED page, which includes a link to the full video.

All Q&A solutions have some inherent reward for the value system of the brain. When you answer someone else's question, one part of your brain is happy that you solved the problem, another is happy that you were able to help another person, another is happy that you're superior to the asker in some way, &c. Even without rep and badges, the voting system enhances the amount of value/worth that answerers can mentally assign themselves; it's much better to feel validated by seeing that five other people consider your answer helpful than by just getting a vague "thanks, that helped."

These are just initial thoughts while my program compiles; I'll add to this later.

EDIT (mostly @Rising Star): I know I missed the bounty deadline, but this is turning into quite the paper. The "add to this later" is still coming.

  • 2
    You too do your SO stuff while your programs compile? Amusing.
    – Grace Note StaffMod
    Commented Jul 9, 2010 at 18:14
  • Don't you guys have fast compilers? :) Commented Jul 13, 2010 at 0:30
  • @George: What, and miss out on all the SO and Meta goodness?
    – Pops
    Commented Jul 13, 2010 at 3:47
  • SO, yes. Meta? Uh... I could live without that. Commented Jul 13, 2010 at 6:36
  • 2
    @GraceNote I guess swordfighting is not every developers fun activity: xkcd.com/303
    – user226495
    Commented Apr 26, 2014 at 20:55
  • @Pops, It has been proven (on many sites without rep/badges) that without rep and badges people will still participate. But it will be harder to claim that such participation is any close to that when rep and badges are involved.
    – Pacerier
    Commented Dec 3, 2015 at 22:58

Esteem and Self Actualization. We're not hunting for food, it's not a survival need. alt text http://www.cbc.ca/radio2/programs/maslow.png

  • 19
    I donno... Pretty sure there are at least a few forms of participation that would qualify as "excretion"...
    – Shog9
    Commented Jul 9, 2010 at 19:00
  • @shog9 I about spit coffee when I read your comment. Good one! Commented Jul 9, 2010 at 19:08
  • We're not hunting for food, but we are hunting for questions we can answer and gather that l33t rep so that the girls will beg us for attention. So far, this post has generated 30 more rep for me. That's 30 rep on meta stackoverflow and I am HOT Commented Jul 9, 2010 at 19:57
  • 1
    @Rising Star Rep whoring on Meta is the best way to loose rep fast.
    – rlb.usa
    Commented Jul 12, 2010 at 19:46
  • @rlb.usa: unleash the rep!
    – Randolpho
    Commented Jul 12, 2010 at 20:46

Jon Ericson had a nice related post, The problem with extrinsic motivation, where he posited that the extrinsic motivations of badges, rep, etc. eventually overwhelmed the intrinsic motivations for him, at least.

  • 1
    It's been over a year since I wrote that question and I still haven't returned to Stack Overflow for many of the same reasons I mentioned in the link above. I'm dipping my toe in the Stack Exchange sites once again because of the Gardening (of all things) beta that should be starting soon. We'll see how that turns out. (And thanks for noticing. It's an extrinsic motivation that I appreciate.) Commented May 31, 2011 at 18:31
  • 1
    "Extrinsic" motivation isn't an especially useful (reliable) term. Contingencies are grounded in the external world. What is meant, when "external" and "internal" motivation are discussed - is that with "internal" motivation, the reinforcing contingencies are so distant in time, that they are not readily observable. E.g. one does not become a professor because of "internal" motivation, but owing to less observable reinforcers, e.g., social status, discriminated/conditioned (academic) peer reinforcement. Skinner, B. F. (1953). Group Control. In Science and human behavior (pp. 323–329).
    – d-cubed
    Commented Apr 22, 2014 at 13:18
  • 1
    Indicating that "extrinsic" motivation replaces "intrinsic" motivation - more accurately indicates that a thicker, more observable reward schedule subsumes a more beneficial (thinner) schedule of (variable ratio) reinforcement. As such, the new 'extrinsic' schedule functions as an aversive stimulus. This problem isn't new- long term reinforcement schedules have to be trained. This also relates to rule governed behavior. Baum, W. M. (2005). Responsibility and the consequences of behavior. In Understanding behaviorism: Behavior, culture, and evolution(pp. 205–210).
    – d-cubed
    Commented Apr 22, 2014 at 13:35

The motivation can be understood by considering two phases of user journey on the platform - namely the newbies and experienced users (those who have answered few questions)

For newbies, the motivations are -

  1. Epic meaning and calling: giving meaning to one's existence, creating an impact by helping the community
  2. Social influence and relatedness: social validation when your answer gets upvoted; sense of pride when you gain reputation points and badges because others can see them (this is again social validation)

The badges and reputation points also act as an extrinsic motivators but they work only because other users can associate a status with them which gives them a meaning.

For experienced users, the above core drives are present but a bigger motivation is 'Unpredictability' - uncertainty of when upvote might be received. This is the same drive which makes people addicted to gambling. This aspect is explained well in Aarobot's answer. The reputation points and badges also play an important role at this stage. This might lead to users constantly hunting for questions to answer (this being pointed out in the question).

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