&gt; Is there evidence that saying &#x27;umm&#x27; and &#x27;ahh&#x27; reduces your ability to communicate effectively? Why are they bad?<p>Hmm I can&#x27;t find any good research though at least anecdotally it makes it a lot hard for me to pay attention. Take Paul Graham for instance. Smart guy, great speaker but his frequent &quot;umms&quot; ended up taking me out of his talk and then I couldn&#x27;t concentrate on anything but his &quot;umms&quot;. I love reading his essays but I find it hard to concentrate on his speaking.<p>Granted I don&#x27;t know if that says something negative about my ability to concentrate, about Paul&#x27;s speaking ability, or both and it&#x27;s anecdotal so no idea if my experience is common.