( CNN ) -- It 's every flier 's worst nightmare : Your pilot announces , `` We 're all going down ! '' and starts shouting about bombs and terrorists . He abandons the cockpit , frantically running up and down the aisles like a man unhinged . What do you do ? That 's what passengers on a JetBlue flight had to decide Tuesday when their pilot , Capt . Clayton Osbon , seemed to have a meltdown in the air between New York and Las Vegas . Fortunately for everyone on board , a quick-thinking co-pilot and some alert passengers snapped into action . Initial reports suggest that at least four passengers leapt to their feet and subdued the pilot , who had been trying to break down the cockpit door after his co-pilot locked him out . The heroic passengers have been praised for their bravery , and rightly so : They may have saved 141 lives on the plane , and maybe more on the ground . It 's hard to hear this story and not admire their swift and effective action -- and wonder how you 'd respond in the same situation . Would you jump up and subdue a hysterical pilot or sit paralyzed in your seat ? Hundreds of studies have explored the so-called `` bystander effect , '' trying to determine why some observers respond positively to a crisis while others ignore it . The research points to a somewhat surprising conclusion : Generally speaking , only subtle differences separate the bystanders from the heroes . Most of us , it seems , can fall into either category depending on the details of a situation . The JetBlue crisis highlights some of the factors that can make a difference , suggesting how we can get people -- ourselves included -- to take action in an emergency . It might seem obvious that when confronted with a raving man attacking a cockpit door , people would realize they should do something to stop him . But that 's not always the case , especially when they 're part of a large crowd . In fact , in one famous study , social psychologists John Darley and Bibb Latane left people alone in a room and pumped in smoke -- a pretty clear warning sign of danger , maybe on par with a 250-pound guy in a pilot 's uniform shouting incoherently about Iran and Iraq . When people were alone in the room , they left and reported the smoke to someone else 75 % of the time . But when there were three people in the room , they reported the smoke 38 % of the time , illustrating the problem psychologists call `` pluralistic ignorance , '' where we mistake other people 's inaction as a sign that everything 's actually OK. After all , no one wants to be the fool who tackles your plane 's pilot because you misread the situation -- maybe he was just playing a practical joke ? When we do n't see anyone else respond , we tend to assume there is n't really a crisis ; as a result , we inadvertently hold each other back . But response rates shoot up dramatically when one bystander simply acknowledges to another that there might be a problem . So on the JetBlue flight , it helped tremendously that the co-pilot and a flight attendant had the presence of mind to use the public address system to call on the passengers to restrain the pilot . It becomes nearly impossible to assume there is n't really a problem when your acting captain says there is . Yet even once we recognize there 's a problem , in crowds we often fall prey to what 's called a `` diffusion of responsibility , '' where we assume the people around us are going to help , so there 's less of a need for us to take action ourselves . Research by Darley and others shows that the greater the number of people who witness a crisis , the lower the odds that any of them will do anything . To overcome this , it helps when we 're singled out personally . Darley once told me that if you ever sprain your ankle in public , do n't just call for help -- pick out someone in the crowd and say , `` Hey , you there , can you give me a hand ? '' On the JetBlue flight , it seems like the crew only made a blanket appeal to the passengers for help , which probably was n't as effective as it could have been . Only four passengers out of nearly 150 sprang to action -- responsibility still might have been pretty diffused . But it likely helped that several of the plane 's passengers were retired or off-duty law enforcement on their way to a security convention in Las Vegas . Darley 's research has found that personality does n't necessarily predict whether someone will help . What 's more important is whether bystanders have the experience to recognize a crisis when it 's unfolding and feel like they have the skills to do something about it . So it probably should come as no surprise that among those who sprang to action , one was a former prison guard and another was an ex-New York police sergeant with 22 years of experience on the force . That sergeant , Paul Babakitis , told CBS News that when he saw the pilot running amok , `` my training immediately kicked in . '' He said he believed he was `` deranged '' when he looked into his eyes because he had `` dealt with a lot of emotionally disturbed people during my time on the force . '' People who have experience in law enforcement or the military are probably better at recognizing a crisis because they 're less likely to convince themselves that this could n't be happening to them , could it ? Of course , `` pluralistic ignorance '' might be harder for any of us to maintain on a plane after 9/11 , even 10 years later . It 's harder today to rule out the plausibility of any crisis . Indeed , Babakitis said he immediately thought of that day when he saw Osbon storming the cockpit . `` Not again , '' he told himself , `` not while I 'm on this plane . '' The opinions expressed in this commentary are solely those of Jason Marsh .
Jason Marsh calls quick action of the passengers with captain admirable . He says ` ` no way out '' situation inhibited ` ` bystander effect , '' where people do n't ' . He says research shows people usually hang back , relying on others to take on danger . Marsh : People asking for help made a difference , as did law enforcement passengers .