Zeigen

With the news yesterday of the untimely passing of Heath Ledger, I’ve heard several people remark on the frequently-expressed belief that deaths (like sneezes?) come in threes. Since Suzanne Pleshette recently succumbed to cancer (on January 17), some wondered who will be the “third” actor/actress to die. Others who were familiar with Brad Renfro’s death (on January 15) expressed instead the idea that Heath’s overdose was the completion of a series of three.

I have to wonder about this superstition. On one hand, it’s not falsifiable. People die all the time. Since the belief doesn’t express a timeframe for how close in succession the deaths have to occur, eventually three people in a related field will die, and the “prophecy” of death coming in threes will be fulfilled.

Any belief that isn’t falsifiable contributes nothing. Suppose ten musicians were to die in quick succession starting next week. Adherents to this belief would group them into three groups of three deaths, then posit after the tenth that two more musicians would die — and eventually (once we wait long enough) indeed two more would. So the prediction has come true! But the actual number of people dying doesn’t change the superstition (they’d believe the same thing even if the number was two, eight, nine, ten, or twenty), and the superstition doesn’t actually predict anything — just that over time people do, in fact, die.

Secondly, who or what is the agent that enforces the trio of deaths? If I learn about two bloggers who die, does that knowledge somehow make me more likely to get into an accident? Is there a grim reaper with a quota of three who (like in the movie series Final Destination) sets up a fatal chain of events for arbitrary professions?

Monitoring a list of recent deaths to see if the number is divisible by three turns up the quite predictable result that the number is only divisible by three about a third of the time.

In conclusion, this belief is an example of selective perception; You tend to remember the times when there was a grouping of three seemingly-related deaths in a short period of time, which reinforces the belief, but tend to forget the times when there wasn’t a pattern.

As I’ve said before, our brains are remarkably good similarity detectors (whereas computers are excellent difference detectors; this is why captchas work), so we often find ourselves picking out plausible-seeming patterns to events that ultimately are chaotic and unpredictable.

And on a personal note, I thought Heath was a gifted actor with a great career in front of him, and I was saddened to hear the news of his death.

This entry was posted by Stephen on Wednesday, January 23rd, 2008 at 4:20 pm and is filed under skepticism. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.