So you want to get a PhD in (cognitive) neuroscience or psychology
A collection of random bits of information and pieces of advice for anyone considering a PhD in cognitive neuroscience or psychology (i.e., sort of what I do).
You will be tempted to ask professors for advice. This isn't a horrible idea, but keep in mind that lots of people start a PhD program who do not end up as a professor. So if you only talk to professors, you are getting a biased and limited sample of the career paths available to you. And, people who stay in academia may have a different view than those who didn't. So by all means, talk to professors, but take any advice with a grain of salt, and consider also talking to people who have taken other routes in their careers.
Picking a mentor and lab
Your PhD supervisor is probably the single biggest factor in your graduate school experience. This is true in a big-picture, theoretical sense, in that you will be exposed to their way of thinking about the world, performing experiments, and writing papers. But it is also true because they will be the ones supporting your career through introductions, letters of recommendation, and general mentoring (or lack thereof). Ideally you will find someone who does good science, is a good mentor, and with whom you get along personally.
The lab of your supervisor is also critical, and is difficult to judge without visiting in person. Do you get along with the other lab members? Is it a competitive culture, or supportive? Do people hang out outside of lab? What are the expectations regarding lab hours or time off? Etc.
Many neuroscience programs operate on a rotation system, where students spend ~10 weeks in 3-4 different labs during their first year completing short research projects before committing to a dissertation lab. I am a big fan of the rotation system for multiple reasons:
No matter how good a fit a mentor is on paper, in real life — even with smart, well-intentioned, considerate people — sometimes it's just not a good fit. (And sadly, sometimes people are just jerks.)
You may not realize your interest in a topic until you are exposed to it. In my PhD program there were many people who stuck with the research they thought they wanted to do before grad school. But, there were also people who completely switched topics, going from mouse molecular biology to cognitive psychology and vice versa.
Even if you don't switch topics, you will probably never have another time to explore different research areas in such a hands-on way, and you may well be teaching about these topics. Or, you may learn some ways of thinking or analyzing data that are helpful in the future. To this day I still regret not spending a rotation in an electrophysiology lab across the hall.
Department and university considerations
The overall intellectual environment of your department and institution will have a considerable influence on your development as a scholar, and the reputation of the school or department may have an impact on your future options (although it's probably not the most important factor).
It is definitely worth checking on non-academic aspects of the institution. As just one example, the University of Rochester recently went through a tumultuous time because of a professor sexually harassing students and the department and university administration failing to do anything about it (see here, here, here...). So don't go to the University of Rochester (or other institutions with similar issues).
Geography and culture
In all likelihood you will be in a PhD program for 5+ years, so it's worth considering where you are living. How's the climate? The culture? The cost of living? You may be willing to make compromises (and many people do), but don't ignore these practical factors as you make a decision.
To take a gap year (or two) or not
Taking a year or two between finishing an undergraduate degree and going on to graduate school can give you time to explore some options, and may also help you to be a stronger candidate in the competitive world of PhD program applications. This is especially true if you can get a position as a research assistant (many of which will want a 2-year commitment). Of course, the benefits are weighed against the additional time.