<p>The year of research absolutely helps, and I don’t mean to imply that it doesn’t.</p>
<p>I’m just thinking about the mechanics of getting good letters, which will vary according to how you actually proceed, and if you want to graduate early, you have to think carefully about these logistics in advance. Say you UROP in one lab as an undergrad, and continue in that lab as a tech for a year. That’s only one letter – you would have to have two letters from professors whom you have impressed in class, which would likely be more difficult if you only have three years to take classes (depending on how quickly you mature into an independent, creatively-thinking scientist). So a better strategy might be to UROP in one lab and tech in another, which would net you two letters about your research abilities. </p>
<p>Overall, it’s better to have more letters from professors who have seen your research abilities firsthand, but you don’t really want to lab-hop if you can help it. Getting letters from professors you had in class is often less than ideal, because grad school admissions committees are interested in your ability to do research, and not as much in your ability to do well in class per se.</p>
<p>The only other way graduating early can hurt you is that a PhD is something of an endurance test, and a major consideration when admitting students for grad school is whether the student will want to/be able to stick with a tough research project for 5+ years. So maturity is a big consideration, and people applying straight out of undergrad (and particularly people graduating early) have to prove that they know exactly why they’re applying. This is something you can address in your application, but it’s good to be aware that it’s an issue that exists.</p>