Using affirmative phrases: "Do this" versus "Don't do that"
Clarity of language and intent is important. It is to your benefit to be as clear as possible when you speak or write, because clear communication helps you get what you need. Whether you want to change someone's behavior via feedback, or you want them to agree to your suggestion, it helps to understand how words shape the person who's listening.
One way to do this is to speak in the affirmative, rather than the negative.
If you speak in negatives, the person has to take an extra mental step
To understand "Don't do that".... you have to think about "that."
And then reverse it to do the opposite. A better way is to say, "Do this."
If you can save people a mental step, you're doing a kind thing. People are overwhelmed, so avoid adding more friction than you have to. This applies in UX design, marketing call-to-actions, or email requests.
It is to your benefit to reduce friction because that helps people give you what you need.
It's useful when you're giving feedback
Saying "don't" tends to sound reprimanding. This makes you look like the bad guy, even if you're justified in what you're saying.
This is a practical issue. If the person you're giving feedback to starts to get defensive, they stop hearing what you're trying to say. Yes, the person receiving feedback should stay open-minded and remember to listen.
But as the person giving feedback, it's also your responsibility to think about how you're sharing the information. This is a much larger topic, but stating things in the affirmative is one thing that can improve both the clarity of what you're saying ("do this") and the emotional tone (you sound positive).
For example, a good diving coach would say, "Point your toes." Other coaches might say, "Don't do X, Y, Z" which can be confusing when you're mid-air doing a reverse double-somersault tuck into the water. It's simpler to remember what to do – not what not to do.
You sound confident, instead of apologetic
"I can only meet between 11-2pm."
Let's deconstruct the implications of this phrase.
When you say "I can only..." it sounds like you THINK you should be more available. Or that the person has a right to want you to be more available.
This puts you in an unnecessarily weak position. If you can meet between 11-2pm, own it. If the person pushes back, you can explain further, but there's no need to start off with doubt.
Same content, different positioning
Here are examples of the same sentiment, phrased in the negative (left column) and affirmative (right column). This is meant to give you an idea of how the same sentiment can be expressed in different ways. I thought of these off the top of my head, and there are plenty of examples out there. Can you feel the difference in the negative versus affirmative expressions?
Takeaway: Try to notice when you speak in the negative. Spend an extra few seconds to see if you can flip it around to say the same thing in the affirmative. It's something I still think about and actively try to do.
Words shape our thinking, and our thinking shapes the words we choose. Being aware of your own patterns and tendencies can sharpen your ability to communicate your true intent and meaning.