Progress Daily

Stephen Garcia & Avishalom Tor analyzed the results of the the Cognitive Reflection Test & the 2005 SAT exam. They calculated the average number of test-takers per venue in each state, and found that test scores fell as the number of people in the examination hall increased.

They then asked 74 university students to take a timed, easy general-knowledge quiz. Each student completed the test alone, but half were told they were competing against ten other people and the other half that they were competing against 100. All were informed that those whose completion times were in the top 20% would receive $5. Students who believed they were competing against only ten people finished in an average of 29 seconds. Those who believed they were competing against 100 averaged 33 seconds.

They then ran a 2nd experiment, & asked students to imagine they were running a five-kilometre race against 50 people and then against 500 (or, in half of the cases, the other way round). In both notional races the top 10% of competitors would get a $1,000 prize. The researchers told the students to rate, on a seven-point scale, how much faster than normal they would run in each notional race, with a one being slightly faster than normal and a seven being the fastest of their lives. The average value in the competition against 50 others was 5.4; in the competition against 500 it was 4.9. They then asked the participants a series of questions commonly used by psychologists to evaluate an individual’s tendency to compare himself with others in a social environment. They found that those with the highest tendency to make such comparisons had the lowest scores in the notional race against 500 others.

“The N-Effect: More Competitors, Less Competition”

“Psyched out,” The Economist

Two years ago, a study by Carsten Wrosch (”You’ve Gotta Know When to Fold ‘Em: Goal Disengagement and Systemic Inflammation in Adolescence“) demonstrated the importance of giving up inappropriate goals — those teenagers who were better at doing so had a lower concentration of C-reactive protein, a substance (made in response to inflammation and) associated with an elevated risk of diabetes and cardiovascular disease.

A recent study by Dr Wrosch and Gregory Miller (”Depressive symptoms can be useful: Self-regulatory and emotional benefits of dysphoric mood in adolescence“) measured the “goal adjustment capacities” of 97 girls aged 15-19 over the course of 19 months. They asked the participants questions about their ability to disengage from unattainable goals and to re-engage with new goals.They also asked about a range of symptoms associated with depression, and tracked how these changed over the course of the study.

Those who experienced mild depressive symptoms could disengage more easily from unreachable goals. They also proved less likely to suffer more serious depression in the long run.

The prevalence of inappropriately optimistic persistence may help explain why the US has the highest depression rate in the world.

“Mild and bitter,” The Economist

Angus Maddison has estimated that life expectancy during the first millennium AD averaged about 25 years (lots of children died very young and many of the rest survived to middle age). Many more children survived into adulthood after the Industrial Revolution and by the beginning of the 20th century average life expectancy in America and the better-off parts of Europe was close to 50. By mid-century the gains from lower child mortality had mainly run their course & the extra years were coming from higher survival rates among older people. The UN thinks that life expectancy at birth worldwide will go up from 68 years at present to 76 by 2050 and in rich countries from 77 to 83 (women generally live 5-6 years longer than men).

Jim Oeppen and James Vaupel have charted life expectancy since 1840 (”Enhanced: Broken Limits to Life Expectancy“), joining up the figures for whatever country was holding the longevity record at the time, and found that the resulting trend line has been moving upward by about 3 months a year.

In the US, centenarians are the fastest-growing section of the population, with an increase from 3,700 in 1940 to over 100,000 now.

According to Robert Fogel, Western people’s average body size has increased by 50% over the past 250 years. And larger body size is correlated with better health and longer life.

“A world of Methuselahs,” The Economist

According to the UN’s latest biennial population forecast, the median age for all countries is due to rise from 29 now to 38 by 2050. At present just under 11% of the world’s 6.9 billion people are over 60. By 2050 that share will have risen to 22% (of a population of over 9 billion), and in the developed countries to 33%.

In 1900 average life expectancy at birth for the world as a whole was only around 30 years, and in rich countries under 50. The figures now are 67 and 78 respectively.

In the early 1970s women across the world were, on average, having 4.3 children each. The current global average is 2.6, and in rich countries only 1.6. By 2050 the global figure will have dropped to just two, and the world’s population will begin to level out.

“A slow-burning fuse,” by Barbara Beck