In Twelve Angry Men by Reginald Rose, why does the old man change his vote the second time the jury votes?

In the first act of Twelve Angry Men (Rose), the foreman polls the jury after discussion of the case and finds only one juror voting not to convict, Juror Number Eight.  It is clear from the discussion that the other jurors are not all that interested in the concept of innocent until proven guilty or the burden of proving guilt beyond a reasonable doubt.  The jurors show racism, impatience, and a disrespect for the entire process.  It is only Juror Number Nine who has any regard for Juror Number Eight's questions and concerns, and he notes that Juror Number Eight is courageous to stand up to the others, a lone voice for the defendant.  He says he would like to hear more, meaning that he now has a mind open to making a decision based on something more fair and more tangible, no longer willing to bow to the pressure of his peers on the jury. He is the first juror that Juror Number Eight "turns," but by no means the last.