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π Groupthink
Groupthink is a psychological phenomenon that occurs within a group of people in which the desire for harmony or conformity in the group results in an irrational or dysfunctional decision-making outcome. Cohesiveness, or the desire for cohesiveness, in a group may produce a tendency among its members to agree at all costs. This causes the group to minimize conflict and reach a consensus decision without critical evaluation.
Groupthink requires individuals to avoid raising controversial issues or alternative solutions, and there is loss of individual creativity, uniqueness and independent thinking. The dysfunctional group dynamics of the "ingroup" produces an "illusion of invulnerability" (an inflated certainty that the right decision has been made). Thus the "ingroup" significantly overrates its own abilities in decision-making and significantly underrates the abilities of its opponents (the "outgroup"). Furthermore, groupthink can produce dehumanizing actions against the "outgroup". Members of a group can often feel peer pressure to "go along with the crowd" in fear of rocking the boat or of what them speaking up will do to the overall to how their teammates perceive them. Group interactions tend to favor, clear and harmonious agreements and it can be a cause for concern when little to no new innovations or arguments for better policies, outcomes and structures are called to question. (McLeod). Groupthink can often be referred to as a group of βyes menβ because group activities and group projects in general make it extremely easy to pass on not offering constructive opinions.
Some methods that have been used to counteract group think in the past is selecting teams from more diverse backgrounds, and even mixing men and women for groups (Kamalnath). Groupthink can be considered by many to be a detriment to companies, organizations and in any work situations. Most positions that are senior level need individuals to be independent in their thinking. There is a positive correlation found between outstanding executives and decisiveness (Kelman). Groupthink also prohibits an organization from moving forward and innovating if no one ever speaks up and says something could be done differently.
Antecedent factors such as group cohesiveness, faulty group structure, and situational context (e.g., community panic) play into the likelihood of whether or not groupthink will impact the decision-making process.
Groupthink is a construct of social psychology, but has an extensive reach and influences literature in the fields of communication studies, political science, management, and organizational theory, as well as important aspects of deviant religious cult behaviour.
Groupthink is sometimes stated to occur (more broadly) within natural groups within the community, for example to explain the lifelong different mindsets of those with differing political views (such as "conservatism" and "liberalism" in the U.S. political context ) or the purported benefits of team work vs. work conducted in solitude. However, this conformity of viewpoints within a group does not mainly involve deliberate group decision-making, and might be better explained by the collective confirmation bias of the individual members of the group.
Most of the initial research on groupthink was conducted by Irving Janis, a research psychologist from Yale University. Janis published an influential book in 1972, which was revised in 1982. Janis used the Bay of Pigs disaster (the failed invasion of Castro's Cuba in 1961) and the Japanese attack on Pearl Harbor in 1941 as his two prime case studies. Later studies have evaluated and reformulated his groupthink model.
Discussed on
- "Groupthink" | 2013-09-02 | 14 Upvotes 11 Comments
- "Groupthink" | 2010-08-15 | 17 Upvotes 4 Comments
π Free energy principle
The free energy principle tries to explain how (biological) systems maintain their order (non-equilibrium steady-state) by restricting themselves to a limited number of states. It says that biological systems minimise a free energy function of their internal states, which entail beliefs about hidden states in their environment. The implicit minimisation of variational free energy is formally related to variational Bayesian methods and was originally introduced by Karl Friston as an explanation for embodied perception in neuroscience, where it is also known as active inference.
The free energy principle is that systemsβthose that are defined by their enclosure in a Markov blanketβtry to minimize the difference between their model of the world and their sense and associated perception. This difference can be described as "surprise" and is minimized by continuous correction of the world model of the system. As such, the principle is based on the Bayesian idea of the brain as an βinference engineβ. Friston added a second route to minimization: action. By actively changing the world into the expected state, systems can also minimize the free energy of the system. Friston assumes this to be the principle of all biological reaction.. Friston also believes his principle applies to mental disorders as well as to artificial intelligence. AI implementations based on the active inference principle have shown advantages over other methods.
The free energy principle has been criticized for being very difficult to understand, even for experts. Discussions of the principle have also been criticized as invoking metaphysical assumptions far removed from a testable scientific prediction, making the principle unfalsifiable. In a 2018 interview, Friston acknowledged that the free energy principle is not properly falsifiable: "the free energy principle is what it is β a principle. Like Hamiltonβs Principle of Stationary Action, it cannot be falsified. It cannot be disproven. In fact, thereβs not much you can do with it, unless you ask whether measurable systems conform to the principle."
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- "Free energy principle" | 2018-07-14 | 79 Upvotes 19 Comments
π A mathematical proof by an anonymous 4chan user
In combinatorial mathematics, a superpermutation on n symbols is a string that contains each permutation of n symbols as a substring. While trivial superpermutations can simply be made up of every permutation concatenated together, superpermutations can also be shorter (except for the trivial case of n = 1) because overlap is allowed. For instance, in the case of n = 2, the superpermutation 1221 contains all possible permutations (12 and 21), but the shorter string 121 also contains both permutations.
It has been shown that for 1 β€ n β€ 5, the smallest superpermutation on n symbols has length 1! + 2! + β¦ + n! (sequence A180632 in the OEIS). The first four smallest superpermutations have respective lengths 1, 3, 9, and 33, forming the strings 1, 121, 123121321, and 123412314231243121342132413214321. However, for n = 5, there are several smallest superpermutations having the length 153. One such superpermutation is shown below, while another of the same length can be obtained by switching all of the fours and fives in the second half of the string (after the bold 2):
12345123Β41523412Β53412354Β12314523Β14253142Β35142315Β42312453Β12435124Β31524312Β54312134Β52134251Β34215342Β13542132Β45132415Β32413524Β13254132Β14532143Β52143251Β432154321
For the cases of n > 5, a smallest superpermutation has not yet been proved nor a pattern to find them, but lower and upper bounds for them have been found.
π Purple Earth Hypothesis
The Purple Earth Hypothesis (PEH) is an astrobiological hypothesis, first proposed by molecular biologist Shiladitya DasSarma in 2007, that the earliest photosynthetic life forms of Early Earth were based on the simpler molecule retinal rather than the more complex porphyrin-based chlorophyll, making the surface biosphere appear purplish rather than its current greenish color. It is estimated to have occurred between 3.5 and 2.4 billion years ago during the Archean eon, prior to the Great Oxygenation Event and Huronian glaciation.
Retinal-containing cell membranes exhibit a single light absorption peak centered in the energy-rich green-yellow region of the visible spectrum, but transmit and reflect red and blue light, resulting in a magenta color. Chlorophyll pigments, in contrast, absorb red and blue light, but little or no green light, which results in the characteristic green reflection of plants, green algae, cyanobacteria and other organisms with chlorophyllic organelles. The simplicity of retinal pigments in comparison to the more complex chlorophyll, their association with isoprenoid lipids in the cell membrane, as well as the discovery of archaeal membrane components in ancient sediments on the Early Earth are consistent with an early appearance of life forms with purple membranes prior to the turquoise of the Canfield ocean and later green photosynthetic organisms.
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- "Purple Earth Hypothesis" | 2025-07-24 | 286 Upvotes 79 Comments
π Thunderstone (folklore)
A thunderstone is a flint tool or fossil turned up by farmer's plow that was thought to have fallen from the sky. They were often thought to be thunderbolts. It was not until travelers returned from far-away places where these implements were in use among primitive cultures that the origins of these objects became known. Even then, these travelers' tales received little popular credence.
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- "Thunderstone (folklore)" | 2018-09-15 | 36 Upvotes 3 Comments
π Pi Day
Pi Day is an annual celebration of the mathematical constant Ο (pi). Pi Day is observed on March 14 (3/14 in the month/day format) since 3, 1, and 4 are the first three significant digits of Ο. In 2009, the United States House of Representatives supported the designation of Pi Day. UNESCO's 40th General Conference decided Pi Day as the International Day of Mathematics in November 2019.
Pi Approximation Day is observed on July 22 (22/7 in the day/month format), since the fraction β22β7 is a common approximation of Ο, which is accurate to two decimal places and dates from Archimedes.
Two Pi Day, also known as Tau Day for the mathematical constant Tau, is observed on June 28 (6/28 in the month/day format).
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- "March 14 (3/14): Pi Day" | 2024-03-14 | 143 Upvotes 94 Comments
- "Pi Day" | 2018-03-14 | 10 Upvotes 4 Comments
- "Pi Day" | 2015-03-14 | 67 Upvotes 30 Comments
- "Pi Day" | 2013-03-14 | 118 Upvotes 49 Comments
- "Happy Pi Day" | 2009-03-14 | 30 Upvotes 11 Comments
π Battery Nomenclature
Standard battery nomenclature describes portable dry cell batteries that have physical dimensions and electrical characteristics interchangeable between manufacturers. The long history of disposable dry cells means that many different manufacturer-specific and national standards were used to designate sizes, long before international standards were reached. Technical standards for battery sizes and types are set by standards organizations such as International Electrotechnical Commission (IEC) and American National Standards Institute (ANSI). Popular sizes are still referred to by old standard or manufacturer designations, and some non-systematic designations have been included in current international standards due to wide use.
The complete nomenclature for the battery will fully specify the size, chemistry, terminal arrangements and special characteristics of a battery. The same physically interchangeable cell size may have widely different characteristics; physical interchangeability is not the sole factor in substitution of batteries.
National standards for dry cell batteries have been developed by ANSI, JIS, British national standards, and others. Civilian, commercial, government and military standards all exist. Two of the most prevalent standards currently in use are the IEC 60086 series and the ANSI C18.1 series. Both standards give dimensions, standard performance characteristics, and safety information.
Modern standards contain both systematic names for cell types that give information on the composition and approximate size of the cells, as well as arbitrary numeric codes for cell size.
Discussed on
- "Battery Nomenclature" | 2019-07-14 | 16 Upvotes 3 Comments
π Krista and Tatiana Hogan
Krista and Tatiana Hogan (born October 25, 2006) are Canadians who are conjoined craniopagus twins. They are joined at the head and share a skull and a brain. They were born in Vancouver, British Columbia, and are the only unseparated conjoined twins of that type currently alive in Canada. They live with their mother, Felicia Simms, in Vernon, British Columbia, have two sisters and a brother and often travel to Vancouver for care at BC Children's Hospital and Sunny Hill Health Centre for Children.
π Visualizing Pi (Ο)
An animated image showing the definition of pi. A number line is marked off by a circle of unit diameter. Starting from zero, the circle "unrolls" its circumference. At one full turn, the unrolled circumference has extended to the point we call Ο. This number is real but irrational, transcendental, and cannot be constructed with compass and straightedge.
Animation credit: John Reid
Archive - More featured pictures...
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- "Visualizing Pi (Ο)" | 2009-09-26 | 48 Upvotes 15 Comments
π Berkson's Paradox
Berkson's paradox also known as Berkson's bias or Berkson's fallacy is a result in conditional probability and statistics which is often found to be counterintuitive, and hence a veridical paradox. It is a complicating factor arising in statistical tests of proportions. Specifically, it arises when there is an ascertainment bias inherent in a study design. The effect is related to the explaining away phenomenon in Bayesian networks, and conditioning on a collider in graphical models.
It is often described in the fields of medical statistics or biostatistics, as in the original description of the problem by Joseph Berkson.
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- "Berkson's Paradox" | 2022-11-20 | 101 Upvotes 10 Comments
- "Berkson's Paradox" | 2018-12-12 | 87 Upvotes 21 Comments
- "Berkson's Paradox" | 2014-09-03 | 39 Upvotes 20 Comments