> What always stands out to me about Sir Roger Bannister is that once he broke 4, then others could too.

> It reminds me how many of our limits are mental and if you think you can't you definitely can't. But if you think you can, just maybe you will...

There is an article here debunking the idea that breaking the 4 minute barrier had any psychological effect on other runners:

http://www.scienceofrunning.com/2017/05/the-roger-bannister-...

TLDR - the mile record times at that period closely track the 1500m times, which had no similar 'psychological' barrier. Also the impact of WW2 had slowed down record breaking leading up to that time.