Negative comments engage avoidance motivation. When you’re motivated to avoid something bad, then an important strategy is to be vigilant for more bad things in the environment to make sure that you’re aware of problems as soon as they happen.

This may have been an adaptive strategy when there were people or animals out there trying to hunt you in some evolutionary environment. However, it’s a less effective strategy in today’s world, when the negative thing is not a bear but a nasty tweet. Despite this, your brain reacts in the same way, making you obsess about what some anonymous troll said.

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Of course not all comments should be ignored. It’s useful to pay enough attention to negative comments to decide whether there are any changes to your own behavior that you want to make. If so, make a note of it so that you can improve your performance in the future. But, even in these cases, you’ll still need to find a way to move forward. —Fast Company