How difficult and common is it to switch labs after starting a PhD?
The reason it is difficult to answer this is that it can depend to a large extent on personalities. A &quot;new&quot; advisor might not want to take you on thinking about their relationship with the &quot;old&quot; advisor. The &quot;old&quot; advisor might feel insulted and cause problems for you. You might, after a year, have responsibilities to the current lab that will be difficult to transfer. It can be a mess, but it happens.
Rather, I'd suggest that you make a commitment to a lab and stick to it. Your doctoral studies aren't your career and it is always possible to change direction after you finish a PhD, especially if it is within the same field. Changing labs can set you back, leaving you with a &quot;lost&quot; year as well as bad feelings.
But, for a bachelors degree holder starting doctoral studies immediately, the first order of business is passing comprehensives, which requires coursework for most. If you don't need to make a serious commitment to the research of a lab (as is true for most) then switching is generally easy and non-disruptive.
The research leading to the dissertation is to teach you how to do it within your field and how to write scholarly papers. Once you get that, the specifics of how you spend your career are pretty malleable.
That said, don't choose something you hate or you will lose motivation. If you start in something and have an opportunity to move before you finish and it isn't too disruptive, then you have an opportunity. But no answer here will guarantee that such an opportunity will arise. A straight path may be the quick path.