With many people now constantly stuck on their handheld devices, from tablets to smartphones, we live in a world of screens. When Nikhom Thephakaysone brought out a .45 caliber gun in a crowded Muni train, no one noticed him. Thephakaysone brandished the weapon several times but no one saw him as the passengers were all too busy checking their mails and updating their Facebooks. Only after he shot a 20-year-old Justin Valdez did the passengers become aware that someone on board had a gun.

District Atty. George Gascón told the San Francisco Chronicle that the problem was indeed the way people live nowadays, a distracted sort of living, meandering from place to place, unmindful of the surroundings. "These people are in very close proximity with him, and nobody sees this. They're just so engrossed, texting and reading. They're completely oblivious of their surroundings," Gascón said.

This particular shooting incident in San Francisco is not the only screen-related incident that occured in recent times. In 2007, there were about 600 injuries related to people looking at their phones instead of paying attention to the task at hand. In 2010, the case climbed up to 1,500. This is what Ira E. Hyman, a psychology professor at Western Washington University, called "inattentional blindness." He and his co-author Jack Nasar said these injuries are surely projected to rise up in the coming years as we become more and more dependent on our handheld devices.

San Francisco police have also admitted that cellphones are somewhat a mixed blessing. Camera phone videos have been instrumental in solving some crimes around the area. But two out of three muggings are related to texting and not being aware of one's surroundings. Even when asked to describe their attackers, victims could not answer as they were too distracted. It is definitely something that civilians should keep in mind as they go through their daily routines.

Suspect Shooter Thephakaysone was arrested after the incident and charged for possession of an illegal assault rifle for a different incident, which occured earlier.