Martin on "[Plugin: WordPress SEO by Yoast] "Where did my page ranking go?" Said the Google user"

In considering Google, you will never know however there are some defined best practice areas you should consider as part of your online structure. With that in mind, I'd suggest you hunt down a cheat sheet on those so you are consistent in your approach and not end up doing random and isolated things to your site.
Changing one page is unlikely to have a great affect on rank.
Why not change your title to Welcome to Pyschology Standard? Though its more likely your visitors eyeballs are reading your content than your page title too so keep in mind it's about your visitors and their experience.