<p>Sometimes I pair-program, or more usually pair-debug, as a teaching technique: solve a problem while screen sharing, narrating my thoughts and reasoning out loud to show the other person how to track down whatever kind of problem it is.</p><p>But it has to be on a reasonably simple problem, because narrating my thoughts coherently _also_ requires thought and effort, and that reduces the amount of brain I have available for the actual problem. For the hardest problems I&#39;m capable of solving at all, the solving and the explaining don&#39;t both fit in my head at once, and I have no choice but to say &quot;sorry, I need to concentrate completely on this, and once I&#39;ve found the answer, _then_ I&#39;ll tell you how I did it.&quot;</p><p>This week, someone pointed out the contrast between this and the &#39;rubber duck&#39; / &#39;cardboard programmer&#39; effect, in which explaining out loud what&#39;s confusing you can _help_ you to figure it out yourself. I&#39;d never noticed that contrast before.</p><p>So, some problems become easier to solve if you talk through your thoughts out loud, and others become harder. That&#39;s annoying! Now you also need the proverbial &quot;wisdom to know the difference&quot;.</p>