Monday, July 21, 2014

The Three Laws of Software Development - Humphrey's Law

(previously published on LinkedIn)
During a recent class, Peter Saddington referenced three laws which collectively are knows as the Three Laws of Software Development:
  1. Humphrey's Law
  2. Ziv's Law
  3. Conway's Law
I had never heard of these observations referenced as "laws" and wanted to explore them further with my own research. Apparently Conway's Law is used in some scholastic software development classes but the other two are a bit obscure to me. We'll start with Humphrey's Law.

Looking up "Humphrey's Law" you first encounter a Wikipedia entry regarding something called "The Centipede's Dilemma" - which is something psychologists call the centipede effect or the centipede syndrome. The reference has to do with what happens when a normal action is interrupted by the person's own awareness of the action. An example might be a baseball player who normally uses his training, muscle memory and a bit of instinct to swing and hit a home run, but because he's consciously aware of what he's doing, he basically over-thinks the action, causing him to strike. The effect is also called hyper-reaction or Humphrey's Law, named for English psychologist George Humphrey, who wrote about the effect in 1923 using a poem by Katherine Craster, usually titled "The Centipede's Dilemma." - yeah I know I'm getting fairly esoteric in this but I think it's good to understand where this stuff comes from.

The Centipede's Dilemma
A centipede was happy – quite!
Until a toad in fun
Said, "Pray, which leg moves after which?"
This raised her doubts to such a pitch,
She fell exhausted in the ditch
Not knowing how to run.

While the poem is interesting it does illustrate the main point, which is "Thus, the eponymous "Humphrey's law" states that once performance of a task has become automatized, conscious thought about the task, while performing it, impairs performance. Whereas habit diminishes and then eliminates the attention required for routine tasks, this automaticity is disrupted by attention to a normally unconscious competence." - rather obscure, right? So the question remains, how does this fit into the Humphrey's Law as referenced by Jeff Sutherland, co-creator of Scrum and where the Three Laws of Software Development idea was presented?

Jeff Sutherland's version of Humphrey's Law states that "users don't know what they want until they see working software" or to paraphrase Peter Saddington, "People don't know what thy want until they see what they don't want." This seems to be the opposite of what "Humphrey's Law" as referenced by psychologists means, although they do share some common threads:
  1. Both ideas are about human response to exterior stimuli
  2. Both ideas are observations which seem true.
  3. Both contain an element of subconscious objectivity
  4. Both share the same name
I had original concluded that they are the same law, only cross-referenced from the perspective of the observer for the Software Development reference, and from the subject (actor(s) aka centipede) in the psychologists' version. Of course this was purely conjecture - and someone commented on my thread on LinkedIn to say that it's actually a different Humphrey - a software developer.

So what about application? These types of laws represent an observable problem, so using the adage that one must first recognize the problem before it can be addressed, the next step is to identify how Humphrey's Law is impacting the development of good software and using various methods to resolve the issue. Peter did a great job illustrating the problem using a "I want a car" technique that I hope to demonstrate to the product guys and my teams at Altisource Labs. I'm working through this now in the form of an interactive class and demonstration which I'll share with you in a subsequent post. In the meanwhile, I'll continue exploring the other two Laws in my next posts.

-- John

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