What is it?
Action bias is a tendency to do something in a situation due to factors like to gain a sense of control, social norms, peer pressure etc. We feel compelled to act even if there is no evidence that it might lead to a favourable outcome. Taking a decision without processing all the information might lead us to take less effective action. In the society, the general bias is against inaction. It gives an impression of not doing what is necessary or not putting in the effort. Against that backdrop, taking premature action might look much better than it actually is. This bias can be considered as a survival instinct. Our innate instinct to hunt, find shelter have carried over despite the very different environment and lifestyle today.
Examples
An example of this bias is when a person would choose to take a medical treatment as it is better than no-treatment at all. Even if the treatment haven't yet been proven to work. In meetings and conversations, we have a tendency to "say something". It doesn't have to actually add to the conversation but it gives a sense of contribution nevertheless. Charlie Munger calls it the Say Something Syndrome in his famous talk. This is common in investing too. Activity from your peers, general market sentiment from news, market activity all can lead to suboptimal action.
