My Contributions to Social Science

It occurred to me that I have reached important insights into human behavior that it would be negligent of me to withhold from the world, so here they are:

The Cheerleader Effect:  The cheerleader effect describes a human perception issue where pictures of any woman in a group are often considered more attractive than a picture of that woman alone (this may apply to men as well, but I have always heard it referred to women).  Apparently women exploit this effect by posting pictures on dating sites that show them in groups of their friends rather than alone.  Anyway, I have developed two corollaries:

  • Polo Shirt Effect:  Polo shirts in a store appear more desirable when grouped with other similar shirts in an array of colors than when presented alone.  This effect is strong enough to trump the paradox of choice, where offering consumers more choices can tend to flummox them and cause them to buy less.  I believe arrays of multi-hued polo shirts presented together increase purchases of these shirts.
  • Christmas Tree Effect:  We almost never buy ornaments for our tree.  95% are individually ugly, but meaningful, constructions by our kids over the years.  The rest are what remain after breakage of some commercial ornaments we bought 20 years ago on deep discount in the after-Christmas sales.  But a tree constructed of these ornaments is beautiful.  So ornaments look far better when massed on a tree than they look individually.

Towards A Theory of Pedestrian Behavior:  One of the things I enjoy is urban running -- ie running through the streets of cities.  When we travel, this is one of my favorite ways to see cities, and it also helps me run further because I do not get bored.  But trying to run through sometimes crowded pedestrian areas can be frustrating, since one is trying to move faster than the crowd and the crowd typically does not expect a runner coming up behind them on the sidewalk.  As a result of many such runs, I have developed two laws of pedestrian behavior:

  1. Groups of pedestrians will expand to fill the width of the space allotted.  If the width changes, groups of pedestrians will respond very quickly and expand their group spacing to fill that width.  While this behavior is almost certainly natural, it is almost impossible to distinguish a group walking naturally from one purposefully trying to block passage by a faster pedestrian.  Corollary:  Groups too small to fill the width of a passage or sidewalk will weave.
  2. Groups of pedestrians, everything else being equal, will choose to pause and congregate at the bottleneck in any sidewalk, thus constricting an already narrow passage.  DisneyWorld is a great location for spotting this behavior.  Corollary:  A disproportionate number of people will choose to stop right at the exit door from an jetway when exiting an aircraft.



  1. Seattle Steve:

    Interesting observation of people exiting jetways. Logically, the passenger flow should follow simple compressible gas formulas, where the gas flows from higher pressure (inside the aircraft) to lower pressure (the larger terminal volume). Perhaps a passenger, upon exiting the jetway, immediately perceives the increased volume thus signaling a suitable place to pause. I wonder if some sort of model based on fluids that change viscosity with changing turbulence, pressure, etc. could more accurately predict this behaviour?

  2. Viktor Elefant:

    I believe the change in environment prompts a person to quickly take stock of what they should do before transitioning between environments, which tends to bring them to a halt and also tend to put their focus away from their immediate environment, which makes them less responsive to the mass of people backing up behind them.

    I'm unaware of something similar happening in fluid dynamics. May work better modeling it as discrete electron flow across a transistor junction where the probability of a person stopping is proportional to the voltage applied across the junction (and other junction characteristics). But then there are other flow modeling problems...

  3. JIMC5499:

    I'll throw one in here. Why do people always pick the narrowest part of a hallway or a doorway to have a conversation? The building that I work in has 12 ft. wide hallways, but, people always have their discussions in the 4 ft. wide doorway. I never really noticed this until I spent a few weeks on crutches.

  4. Dan Wendlick:

    So then how do you model in that the airlines insist on placing the connecting gate information screens there, with the sightline at a right angle to the traffic axis.

  5. Viktor Elefant:

    That would be especially poor design that I actually don't encounter all that often. (Mostly I transfer through CLT).

    In the transistor junction model, that would just increase V_T.

    But that's also not the scenario that I think Warren is describing. Specifically, I think he's considering the situation where people walk through an exit, and then stop for apparently no good reason, like at Disney World or a grocery store.

  6. RobJ:

    Re: #1 Back in the 1980's, a sociologist showed a TV documentary where he filmed pedestrians meeting on the sidewalks of New York. He showed that as such meetings went on, the people involved would gradually move to occupy a larger portion of the sidewalk space. I don't know if he coined a term to describe the phenomenon.
    Since then I've tried to be conscious of meeting others in cramped passageways, and try to move conversations to avoid blocking doorways and hallways.

  7. a nameless coyote:

    Here's a rule.
    Anywhere you want to pause some jackass wants to run through it.

  8. Ally:

    Here's another:
    Anywhere you want to pass through quickly some jackass wants to pause and block the flow of traffic.

  9. jiminstl:

    I once had a woman in front of me stop as she was stepping off the, very crowded, down escalator in a stadium. I had to pick her up to avoid falling over her and both of us being crushed, I am not sure that she understood that I had just saved her life.

  10. Craig Loehle:

    They place the monitor for Delta at some airports right where you get off so departing passengers can find their connections. So people stop. I walk faster than almost everyone so if I do stop I am aware that I am blocking the way, but most people seem completely oblivious. The will spread out their arms and stuff and then walk NOT in a straight line but a sort of constrained random walk so you can't predict if there is room to pass them. Argghhh

  11. TruthisaPeskyThing:

    Two sources of aggravation for me: (1) People who stop walking when getting on an escalator -- and clogging the entire width of escalators so that walkers cannot get by. (2) At receptions, people who congregate around the bar (or the food table), hindering others from getting through.

  12. Maximum Liberty:


    I think your first laws in your theory of pedestrian behavior are:

    1. the law of linear diffusion
    2. the law of constricted congregation

    Here is a third: the law of speedy deference --
    Pedestrians that are relatively quickly moving go around pedestrians who are slowly moving.

    This applies to both pedestrians moving in the same direction and to oncoming pedestrians. It is the latter application that is fun.

    Corollary 1: To move at a slow pace that you don't want interrupted, you can go against the traffic flow. You can stroll along and they will go around you. You must, though, have a tolerance for dirty looks.

    Corollary 2: If you are in pedestrian traffic that comes in bunches, you can speed up through the gaps, so long as you slow down before the oncoming pedestrians look at you. If they initially see you moving faster than them, towards them, it takes a lot for them to recognize that you have slowed down. You will probably end up face-to-face with them wondering why you have stopped them.

    Caveat: This law does not operate on pedestrians in extremely cramped, stop-and-go situations, like moving around in DisneyWorld firght after the fireworks.

    Max L.

  13. bigmaq1980:

    Don't know the laws for this, but it happens in traffic...

    On a highway with two lanes in the same direction, car immediately ahead on left lane slows down when beside another vehicle on right, but speed up after they have passed said vehicle.

    This same car will remain in the left lane after passing, but at an accelerated rate, making passing on the right significantly more difficult before the next vehicle on the right is reached, where the car returns to slower "passing speed".

    There are dozens of other traffic phenomena that are odd and annoying behaviors often which can come back to lack of awareness and courtesy.