An amusing video from a few years back has been making the rounds lately. Dad challenges the kids to write exact instructions to make a peanut butter and jelly sandwich, and Dad follows those instructions. The kids find the experience difficult and frustrating, because Dad interprets the “exact” instructions exactly—but differently from the way the kids intended. I’ll be here when you get back. Go ahead and watch it.
Welcome back. When the video was posted in a recent thread on LinkedIn, comments tended to focus on the need for explicit documentation, or more specific instructions, or clear direction.
In Rapid Software Testing, we’d take a different interpretation. The issue here is not that instructions are unclear, or that the kids have expressed themselves poorly. Instead, we would emphasize that communicating clearly, describing intentions explictly, and performing actions appropriately all rely on tacit knowledge—knowledge that has not been made explicit. In that light, the kids did a perfectly reasonable job at describing the assignment.
Notice that the kids do not describe what peanut butter is; they do not have to not tell the father that one must twist the lid on the peanut butter jar to open it; nor do they have to explain that the markings on the paper are words representing their intentions. The father has sufficient tacit knowledge to be aware of those things. At a very young age, through socialization, observation, imitation, and practice, the dad acquired the tacit knowledge required to open peanut butter jars, to squeeze jelly dispensers without crushing them, to use butter knives to deliver peanut butter from jar to bread, to make reasonable inferences about what the “top” of the bread is, and so forth.
Even though he has sufficient tacit knowledge to interpret instructions for making a peanut butter and jelly sandwich, the dad pretends that he doesn’t. What makes the situation in the video funny for us and exasperating for the kids is our own tacit knowledge of things the father presumably should know as a normal American dad in a normal American kitchen. In particular, we’re aware that he should be able to interpret the instructions competently; to repair differences between the actions the kids intended him to take and the ones he chose to take.
In certain circles, there is an idea that “better requirements documents” or “clear communication” or “eliminating ambiguity” are royal roads to better software development and better testing. Certainly these things can help to some degree, but organizing teams and building products requires far more than explicit instructions. It requires the social context and tacit knowledge to interpret things appropriately. Dad misinterpreted on purpose. Development and testing groups can easily misintrepret by accident; unintentionally; obliviously.
Where do explicit instructions come from? Would they be any good if they weren’t rooted in knowledge about the customers’ form of life, and knowledge of the problems that customers face—the problems that the product could help to solve? Could they be expressed more concisely and more reliably when everyone involved had shared sets of feelings and mental models? And would exact instructions help if the person (or machine) receiving them didn’t have the social competence to interpret them appropriately?
In RST, we would hold that it’s essential for the tester to become immersed in the world of the product and in the customers’ forms of life to the greatest degree possible—a topic for posts to come.
I had the exact same thought when I read the call for better instructions! When I was in school one of my computing teachers gave us a similar exercise in writing out sandwich instructions, then broke down how the instructions fail, then taught us about the infinite void of formal communication. He didn’t use the word “tacit” but the idea stayed with me my whole life, and I was reminded of him when I watched the video, just like I thought of him when reading Tacit and Explicit Knowledge.
And now go and find a short science fiction story by Joanna Russ – “Useful Phrases for the Tourist” – which consists of entries in an interstellar phrase book. (“Please do not let the atmosphere into the room. I shall be most uncomfortable.” “Please do not let the atmosphere out of the room. I shall be most uncomfortable.”)
It’s a very good illustration of the nature of (or the absence of) tacit knowledge.
[…] Exact Instructions vs. Social Competence Written by: Michael Bolton […]
And the point is that where that explicit information is needed and where is not. Misjudgement of these two situation causes continuos miscomprehension and provides a chance for the limurking mistakes to show themselves up.