How many times have you heard that we need to stick together?  The manifestations of this tendency in physics, psychology and sociology are more common that you may have realized. 

           Here are some examples:
 

Cause Result
In physics, surface tension of heated ethanol or acetone causes the liquid to levitate on the tiny teeth of a micro-saw, propelled upwards by a net of escaping gas.  This is according to David Quéré, writing in the November 22, 2011 issue of Europhysics Letters.
 
These drops of liquid appear to defy gravity in their vertical climb.
 
The discovery is potentially useful for cooling microprocessors, according to
Le Monde (29 November 2011).

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People have a natural tendency to reinforce their existing beliefs and to conform those beliefs to the ones maintained by others in their social network. Adding new information tends to reinforce bias, rather than prompting someone to reconsider their position.  Thus, the greater someone’s formal education or pool of data, the more strongly they defend their opinion.
 
Conspiracy theorists, nay sayers as to global warming, Democrats refusing to cut entitlements, and Republicans who believe economic recovery is simply a matter of reducing taxes are all unlikely to be influenced by facts challenging their position, no matter how overwhelming the evidence happens to be.
 
This research conclusion is counter-intuitive.  It suggests that being smarter or more educated does not necessarily make you more critical, more circumspect, or more likely to be right.

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The strength of the identity of an individual
is fundamentally based upon the degree
to which they feel socially connected.
Humans are more social than any other mammal.
 
Individuals of our species define themselves by group membership, whether it be their nation (for example, by displaying a flag), their religion (wearing a symbol of faith on a necklace), their race, or their ethnic origin.
 
National, racial, religious and ethnic groups have characterized human competition throughout history. The degree of competition among groups ranges from discrimination to war and extermination.
 
There are many examples.
  Recently, rival groups that have sought to kill each other include Protestants and Catholics in Northern Ireland, Shiites and Suniis in Afghanistan, and Armenians and Azerbaijanis in the Near East. 

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Cognitive dissonance is the theory of psychology that seeks to explain why we gravitate around preconceptions, and why they are so hard to modify once they are formed. The further a dissonant viewpoint is from our existing belief, the less likely we are to acknowledge or understand it, or modify our own our position.
 
Inconsistent facts get discounted or ignored.  For example, a prosecutor is told that DNA on bedsheets — first obtained post-trial — does not match the man convicted of rape.  The prosecutor then speculated that the DNA might have been left by movers —  third parties unrelated to the crime — who had installed furniture a few days earlier.  “The Prosecution’s Case Against DNA,” by Andrew Martin.  New York Times, November 22, 2011.

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Force of habit. We manage life’s complexity by doing things in patterns; placing them on auto-pilot, if you will.  This frees up our attention for dealing with emergencies. 
 
Habit has inestimable advantages.  The countervailing disadvantage is that habit – like certain beliefs — can be hard to change.  For example, do you continue to trust a priest after they are accused of being a pedophile?
 
Chemical dependency in the brain, which we call addiction, is often impossible to escape.  Addiction is our most extreme habit.

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We evaluate things in ways that are consistent with what we know
and what we are told.
If it is disclosed that someone confessed to  or witnessed a crime, jurors are more likely to validate that story regardless of reliability.

Thus, everyone involved in a "tainted" case has a desire to conform their conduct, perceptions and recollections to the evidence already in place:  Investigators are less likely to search for alternate perpetrators of the crime.  Eyewitnesses mold their testimony to create a consistent theme in defiance of what they may have actually observed.  The percentage of wrongful convictions in these cases of mis-handled evidence climbs dramatically.
 
This risk of prejudicial outcome is the reason why witnesses are not allowed to listen to testimony of other witnesses before testifying themselves.
 
Subtle cues can influence recollection.  Examples include the McMartin pre-school case (children describing sexual abuse that  never occurred), Clever Hans (a horse apparently able to count), and the biased selection of defendants out of police line-ups (much worse accuracy in identifications if the person communicating with the victim about the line-up knows which individual in the array is thought to be the suspect).

Memory is an inherently unreliable method of recalling the past. "The Certainty of Memory Has its Day in Court," by Laura Beil.  New York Times, November 29, 2011, p. D1. 

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We over-generalize based upon personal experience, anecdotal reports, or emotion. This is called economic psychology.  People act based upon a distorted, subjective perspective rather than the actual odds they are facing.

For example, "On 11 September 2001 terrorists killed 3,400 people. But the very same day, a larger number of people died from preventable and curable diseases. In fact, 5,200 Americans die unnecessarily every day through a lack of access to modern medical care."  The Insider, based on BBC News, "War on terror 'causing US deaths'", 9 September 2005. 

The point of this 9-11 example is that more people die from substandard health care than from terrorists.  But as between the two, Homeland Security is a far greater spending priority.

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Fear of failure often causes us to remain with a known quantity rather than gambling on a change that is statistically likely to provide a greater return. People usually stick with the job they have, rather than leaving it for something with a good chance of turning out better, according to a recent study.