You Pay a Big Price When You Interrupt

In conversation, you pay an enormous price every time you interrupt:


It makes the person feel invalidated and thus more likely closed to what you have to say.
It makes the person feel you're rude and thus less likely to support you in anything.
You are making your point when their mind is still focused on what they were saying. As a result, the person may not even fully hear what you're saying.

We rationalize the value of interrupting:


We think it saves time---After all, we're confident we know what they're going to say. Usually but not always we're right but, for the reasons above, we're less likely to obtain the desired result than if we let the person finish talking. True, you can cram more ideas into a conversation by interrupting but that's a poor metric for assessing the conversation's value. What counts is whether behavior change results, and with that metric, you save time by not interrupting.
We think interrupting shows we're motivated, that we care. More likely, it's interpreted as that we can't control ourselves. 
We think that interrupting shows we're smart. It may but the value of that is outweighed by the above negatives. 

If you truly care about being effective, showing that you care about others, and that you are not narcissistic, you will promise yourself that from now on, you will not interrupt, period. Indeed, when someone finishes talking, you will wait a full second before speaking. That makes the person feel you really were listening rather than just waiting for them to finish so you could offer your pearls. It also allows their mind to clear so it's available to truly process what you're going to say.



The no-interrupt/wait-a-second rule also applies to meetings. Often the person who hangs back until the end of a discussion and then, carefully, tactfully, makes a comment will be taken more seriously than the person who has peppered the discussion with comments, especially if s/he interrupted others. 



Of course, if you're an inveterate interrupter, changing is much easier said than done. I believe your best chances of succeeding are:


Establish a zero-tolerance policy: No interrupting, under any circumstance. It's much more likely that you'll make progress with that all-or-nothing policy than if you try to ease off. Having to decide, in the moment, whether to interrupt, is just too difficult.
Tell someone close to you that you're trying to develop a new habit: not interrupting and that you'd appreciate it if every time you interrupt, they not complain but simply raise one finger. That's a quick, minimally threatening way to give you feedback.  Tell them that if they see you jotting things on a memo pad while you're conversing it's because it makes you less likely to interrupt because you won't fear forgetting what you were going to say.

Learning to stop interrupting is crucial but a difficult habit to break. I speak from personal experience. The good news is that you needn't be perfect. If you interrupt, forgive yourself but get back on that wagon. You will reap enormous professional and personal benefits.