# Crowd Control

Tokyo has the world’s busiest train stations, handling 13 billion passenger trips a year. To keep things running smoothly it relies on some subtle features to manipulate passenger behavior.

Blue lights mounted discreetly at either end of a platform, the points at which prospective suicides contemplate leaping into the path of oncoming trains, have been associated with an 84 percent decline in such attempts.

Rail operator JR East commissioned composer Hiroaki Ide to replace the grating buzzer that used to signal a train’s departure with short, pleasant jingles known as hassha melodies. These have produced a 25 percent reduction in passenger injuries due to rushing.

Stations also disperse young people by playing 17-kilohertz tones that can generally only be heard by those under 25. And rail employees are trained to use the “point and call” method, shisa kanko, in executing tasks. Physically pointing at an object and verbalizing one’s intentions has been shown to reduce human error by as much as 85 percent.

(Thanks, Sharon.)

# “To My Pupil”

Lewis Carroll’s 1885 puzzle book A Tangled Tale bears an anonymous dedication:

Beloved Pupil! Tamed by thee,
Division, Fractions, Rule of Three,
Attest thy deft manipulation!
Then onward! Let the voice of Fame
From Age to Age repeat thy story,
Till thou has won thyself a name
Exceeding even Euclid's glory!


He was thinking of Edith Rix, a child-friend who went on to study mathematics at Cambridge. She might have divined without asking that the dedication was intended for her. How?

# The McGurk Effect

In 1976 psychologist Harry McGurk discovered that seeing a person speak affects our impression of the sound we hear. Faced with conflicting information, the brain seems to make its “best guess” as to what it’s perceiving. In some cases a third sound is produced: When the syllables /ba-ba/ are spoken over the lip movements /ga-ga/, the perception is /da-da/.

This casts doubt on the assumption that the senses operate separately and can be studied in isolation. Psychologists and philosophers are still considering the implications.

(Harry McGurk and John MacDonald, “Hearing Lips and Seeing Voices,” Nature 264:5588 [1976], 746.)

# Motivation

Felix Alston, the baseball-obsessed warden of the Wyoming State Penitentiary, wanted his prison’s team to be the best possible. So in 1911 he told his players that so long as they kept winning they would receive stays of execution.

The All Stars were murderers and rapists sentenced to death; they entered and left the field chained together in irons. But in 1911 death sentences were usually carried out within a few months, and the warden’s offer apparently had a strong effect: Between March 1911 and May 1912, the team won 39 of their 45 games.

It couldn’t last. The state supreme court justice who helped arrange the stays (and profited by his bets) came under increasing pressure to carry out the sentences, and when star shortstop Joseph Seng was hanged on May 24, 1912, the team’s winning streak came to an end. In the months that followed, one player escaped, five were hanged, and five were gassed to death. By 1916 the team was a memory.

We ought to apologize for what our ancestors did to other people. This requires that we sincerely regret those deeds. But that means that we would prefer that the deeds had not been done, and if this were the case then world history would be significantly different and we ourselves would probably not exist. Yet most of us are glad to be alive. Can we sincerely regret deeds that are necessary to our own existence?

(That’s from La Trobe University philosopher Janna Thompson. She says the best solution is to interpret the apology as regret for this state of affairs. “[T]he regret expressed is that we owe our existence and other things we enjoy to the injustices of our ancestors. Our preference is for a possible world in which our existence did not depend on these deeds.”)

(Janna Thompson, “The Apology Paradox,” Philosophical Quarterly 50:201 [2000], 470-475.)

# Ellison Words

Science fiction writer Harlan Ellison typed more than 1,700 works using a single finger of each hand. In 1999 Mike Keith set out to learn which words would be easiest for him to type. “Easy” means that successive letters are typed by alternate hands and that the hands travel as little as possible. (See the article for some other technicalities.)

Here are the easiest words of 4 to 13 letters; the score in parenthesis is the total linear distance traveled by the fingers, normalized by dividing by the length of the word (lower is better):

DODO, PAPA, TUTU (0.00)
DODOS, NINON (0.20)
BANANA (0.17)
AUSTERE (0.77)
TEREBENE (0.53)
ABATEMENT (1.12)
MAHARAJAS (0.88)
PROHIBITORY (1.15)
MONOTONICITY (1.19)
MONONUCLEOSIS (1.05)

Ellison could easily have used most of these in a story about an infectious disease outbreak in India. But I guess that might have looked lazy.

(Michael Keith, “Typewriter Words,” Word Ways 32:4 [November 1999], 270-277.)

# The False Position Method

In David Hayes and Tatiana Shubin’s Mathematical Adventures (2004), University of California-Davis mathematician Don Chakerian describes a method used in antiquity for solving an equation in one unknown. He illustrates it with a problem from Daboll’s Schoolmaster’s Assistant (1800):

A, B, and C built a house which cost $500, of which A paid a certain sum, B paid 10 dollars more than A, and C paid as much as A and B both; how much did each man pay? We’ll make two guesses as to how much A paid, check them, and plug the “errors” into a formula to get the right answer. First, suppose A pays$80. That means that B pays $90 and C pays$170, giving a total of $340. That’s 500 – 340 =$160 short of the goal, so our guess of $80 yields an “error” of$160. As a second guess, suppose that A pays $150. In that case B pays$160, C pays $310, and the total is now$620. This time the “error” is 500 – 620 = -$120. The false position method (technically here the double false position method) offers this formula for finding the right answer: $\displaystyle \frac{\left ( \textup{first guess} \right ) \left ( \textup{second error} \right ) - \left ( \textup{second guess} \right ) \left ( \textup{first error} \right )}{\left ( \textup{second error} \right ) - \left ( \textup{first error} \right )}$ In this case it gives $\displaystyle \frac{\left ( 80 \right ) \left ( -120 \right ) - \left ( 150 \right ) \left ( 160 \right )}{ -120 -160 } = \frac{-9600 - 24000}{ -280 } = 120.$ When A pays$120 then B pays $130, C pays 250, and together they pay$500, so this solution works.

This is hardly the most efficient way to solve a simple linear equation given the tools we have today, but it served for centuries. In his Ground of Artes of 1542, Robert Recorde offered a rule:

Gesse at this woorke as happe doth leade.
By chaunce to truthe you may procede.
And firste woorke by the question,
Although no truthe therein be don.
Suche falsehode is so good a grounde,
That truth by it will soone be founde.
From many bate to many mo,
From to fewe take to fewe also.
With to much ioyne to fewe againe,
To to fewe adde to manye plaine.
In crossewaies multiplye contrary kinde,
All truthe by falsehode for to fynde.

dungeonable

# Podcast Episode 250: The General Slocum

In 1904 a Manhattan church outing descended into horror when a passenger steamboat caught fire on the East River. More than a thousand people struggled to survive as the captain raced to reach land. In this week’s episode of the Futility Closet podcast we’ll describe the burning of the General Slocum, the worst maritime disaster in the history of New York City.

We’ll also chase some marathon cheaters and puzzle over a confusing speeding ticket.

See full show notes …

# A New Illusion

Get three empty matchboxes and put a weight in one of them. Lift the weighted box on its own, then put it down and lift all three boxes together. In tests by Isabel Won and her colleagues at Johns Hopkins University, 90 per cent of subjects who tried this said that the weighted box lifted on its own felt heavier than the three boxes lifted together.

“[T]he experience was so striking that subjects often spontaneously and astoundedly commented on its impossibility to the experimenter, and even requested to lift the objects again after the experiment was over,” the authors report. “Anecdotally, those subjects reported that the illusion persisted even during these repeated lifts, including when subjects placed all three boxes on their palm and then suddenly removed the two lighter boxes — distilling the phenomenon into a single impossible ‘moment’ wherein removing weight caused the sensation of adding weight.”

“We suggest that the space of impossible experiences is larger than has been appreciated, extending into a new sense modality. … Impossibility can not only be seen, but also felt.” See the paper for details.

(Thanks, Sharon.)