By Jegoo Lee

If you are a coffee drinker, you may have had a chance to observe coffee brewing. Hot water is poured over ground coffee beans in a cone-shaped filter; the water wells up there for a few seconds, and then seeps down through the coffee particles, resulting in a dark brown liquid that drips into your mug. Clearly, the coffee does not brew instantly, but collects at a certain point before streaming. This is what fluid physicists call a percolation process.

Let’s think about an inquisitive and passionate newbie in Wall Street. This bright-eyed, young person gradually makes friends in the workplace, absorbing and becoming accustomed to what those coworkers do. After a certain amount of time, this person finds her/himself boasting about placing an illegal spoofing order, having imitated and learned from experienced traders. As you might guess, here, something similar to percolation in coffee-brewing, takes place through contact with colleagues. Likewise, white-collar crimes occur once people feel connected to their workplaces and colleagues, i.e., after a phase transition moment.

Suspecting similar patterns between liquid percolation and the corruption process, in our paper, my co-author and I developed a phase transition mechanism of collective corruption, i.e., when or how quickly group members become rotten apples in certain organizations. More specifically, we explained when corruptive behaviors begin to diffuse through dyadic interactions between group members, i.e., so-called social or information percolation. We presented a corruption epidemic similar to some trajectory models for COVID-19 contagion.

Our system dynamics models considered a few individual factors, such as whether each actor has a favorable attitude toward corruption and a high risk-taking propensity. This is analogous to a phenomenon if a dry tree bursts into flames fast from a near burning tree. Our simulation models confirmed that, upon receiving the initiator’s corruption offer, the more corruptible receiver’s phase transition point (i.e., when there is involvement in corruptive behaviors) occurs earlier, just as a combustible tree catches on fire quickly. We also corroborated a recursive phase transition in which, once the receiver’s phase transition takes place, the initiator’s corruption preference is amplified. It is like, in a forest fire, a burning tree making nearby flammable trees blaze up.

We further designed and ran simulation models for more complicated scenarios. First, we examined the situation where the initiator and the receiver have morally good (less likely to become corrupt) or morally bad (more likely to become corrupt) personalities. Phase transitions occur immediately when one actor is good but the other is bad; however, no fast phase transition is found for good-good and bad-bad cases. Second, we tested the power differential between two actors to find that an immediate phase transition occurs when the initiator is more powerful than the receiver. However, when the initiator has a less powerful position than the receiver, the latter actor’s affirmation is very much delayed.

Our study provides food for thought. Although researchers have paid attention to “how” and “why” of corruption, we need to keep an eye out for the timing of collective corruption occurrence. Any organizational member is likely to commit immoral behaviors “when” they become less resistant to risk and undesirable conducts. Thus, continuous caring and effective intervention of potentially vulnerable members, as well as proactive communication channels such as a whistleblowing, are crucial.

So, the next time you’re brewing your coffee, when you capture the moment the hot water begins seeping through the filter, notice the shift from ordinary water to a dark brown beverage with a unique appealing aroma, but also discern its similarity to the spread of corruption – specifically, the phase transition of a manager from a good, organizational citizen to a corrupt one.