Irrational human decision making during a zombie apocalypse

You're in a room full of lumbering zombies and you want to get out quick. Here's a tip: the stress of the situation will make you favour the exit that you're most familiar with even if that's the busiest way out. Give yourself a better chance by checking that there isn't a quieter way to escape the flesh-munchers.

This is the lesson from a study conducted by researchers at the ZombieLab event held at London's Science Museum earlier this year. Nikolai Bode and Edward Codling presented 185 participants (90 women; average age 25) with a computer simulation showing a top-down view of a corridor and a zombie-filled room with two available doorways on opposite sides.

Each participant was represented in the simulation as a black-filled circle which they controlled with a computer mouse. To start they were directed to follow arrows from their initial position in the corridor into the room. For the second phase, their task was to exit the room as fast as possible back to the corridor. During this evacuation phase, the zombies in the room were also attempting to get back out into the corridor.

In a baseline condition, the participants showed no preference for either of the exits. However, when stress levels were ratcheted up with a prominent challenge to beat the current fastest time, the participants' decision making was affected. Under stress, participants were more likely than in the baseline condition to try to exit via the route they used to enter the room, even though this was the most crowded exit favoured by the majority of the zombies.

The result fits with anecdotal observations from real life emergencies. For instance when the Lowenbrauskeller building in Munich was evacuated in 1973, two people were killed in a crush at the main exit as fleeing occupants ignored eight other signposted exits on route.

"Our approach has revealed what can only be described as nonrational human decision making under the influence of the motivational, potentially stress-inducing, treatment," said Bode and Codling. "We suggest that in evacuations with higher stress levels evacuees will be more likely to use known exit routes and less able or willing to adapt their route choices, even if this results in longer evacuation times."

An obvious weakness of the research is that it was based on a computer simulation. Bode and Codling acknowledged this and said their approach presented a mid-way between purely theoretical studies and real-life evacuation drills. Another criticism is with the believability of the horror scenario – if the zombies were rushing to exit the room, why follow them?

Further reading

Nikolai W.F. Bodea, and Edward A. Codlinga (2013). Human exit route choice in virtual crowd evacuations. Animal Behaviour DOI: 10.1016/j.anbehav.2013.05.025