Bystander Effect

Today I read an article (here) that recites 3 incidences of murder where countless bystanders watched as someone (in one incidence police officers) brutally beat another person to death. I recalled one morning while walking to my nanoparticles class, I witnessed two women scuffling on the ground near the intersection of Bayard and Craig Street. I obviously got there late, and didn't know what started the fight, and I stood frozen and unsure what to do. I watched as a fellow student walked right up to the ball of fists on the ground and took a picture on her phone only to walk away immediately after. Luckily the guard of Schenley House can running across the street and forcefully pulled one woman from the top of the other. She took her crying child nearby quickly away from the site, and the other woman exclaimed loudly what kind of person would attack a pregnant woman.

Again I recalled that even with shame, wondering if there was anything I could have done to help. If I were to see someone getting raped in front of me, would I intervene? I want to say "yes, immediately" but am I truly better than the many who watched Kitty get stabbed, then raped, and finally murdered?