The Toothbrush Theory

I have a habit of wandering over to Wikipedia and start reading on anything that I have been thinking about.

Recently, whilst reading, and jumping from one link to the other (there must be a name for such behaviour),  I came across the quote “… any colour, so long as its black” that Henry Ford is said to have quoted in his autobiography.

Debate about the authenticity aside, it also pointed me to a couple of chapters in Dan Ariely‘s The Upside of Irrationality where firstly, using a series of experiments, he demonstrates how we over-value our own creation and how we assume that this bias of over-valuation is shared by others. He then progresses and demonstrates that the same thing happens with our ideas too – the  ‘Not-Invented-Here’ bias, fondly called “The toothbrush theory”. The idea is that everyone wants a toothbrush,  everyone needs one, everyone has one, but no one wants to use anyone else’s.

Simply put, we tend to feel more certain, important and effective about the ideas we come up with than when someone else has done so.

How many times have we as testers felt we had the right idea to test certain things in a certain way? I’ve certainly done that. Innumerable number of times. I still do. I’ve also seen many colleagues fall into this trap.

In one of my earliest testing assignments, I got to see the toothbrush theory in action. I found myself on a young team 3 of whom were recent graduates. Each one a strong character, oozing self confidence! On one of the test cycles we were working on, there was a particularly complex piece of functionality we had to validate via an SQL script.

Impressed at how the new blood had performed during their probation period, the team lead decided to set a final task for the last week of their probation – to see how they worked together. They were tasked to collectively come up with the test script that would validate the business logic.

The three of them chose to spend time on understanding the functionality and working alone before bringing their ideas to the table. Because of the complexity of the functionality, they ended up spending nearly a week coming up with their own versions of the implementation and as expected there was a big row broke over whose idea to implement as a code.

Whilst one wanted to use views to get the qualifying data and then run the script on that, other wanted to use common table expression and the third one wanted to use functions. Merits and demerits of each approach aside, each of their solution would have achieved the same end result, but it was the notion of one idea that was being tested.

The significant amount of time spent by each tester led to the overvaluation of their own approach (endowment bias), which was difficult for them to let go (loss aversion), ultimately shutting themselves off to anyone else’s idea (not-invented-here bias).

Could this have been avoided? Would it have worked better with the way things were?

Perhaps it would have been difficult to rid two of testers of their bias in favour of the third one. If it were possible for someone to somehow convince that the chosen solution was their own brainchild, then yes, perhaps.

What if someone’s ideas constantly ended up being second best; or third best or last for that matter. In fact, what if only one (and the same) person’s ideas were the only ones that were always chosen? It impacts both parties – those whose ideas were chosen and those whose weren’t.

How do we strike a balance? I think it is difficult. Difficult, not impossible.

I think, for a start, it is essential for senior testers, test leads, test managers and co-workers to encourage and inspire each other to take pride and a sense of ownership in the work they are assigned.

But there is a negative side to this too; we could easily manipulate people by giving them false sense of ownership and get things done for ulterior motives!

This post has taken me some time to write and I still have a long way to go – in reading the book, even perhaps revisiting these posts. I may have a change of mind, giving myself a de-biasing opportunity by a sense of disinterest and non ownership!

It would certainly help and allow me to think if you leave your comments!

Thanks for reading.

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1 Comment

  1. Hi,
    How to validate the functionality using SQL scripts?


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