The psy­cho­log­i­cal prin­ci­ple of anchor­ing is most com­monly dis­cussed in terms of our irra­tional deci­sion mak­ing when pur­chas­ing items. How­ever, Jonah Lehrer stresses that anchor­ing is more wide-ranging than this and is in fact “a fun­da­men­tal flaw of human deci­sion making”.

As such, Lehrer believes that anchor­ing also effects our beliefs, such that our first reac­tion to an event ‘anchors’ our sub­se­quent thoughts and deci­sions, even in light of more accu­rate evi­dence.

Con­sider the ash cloud: After the cloud began drift­ing south, into the crowded air­space of West­ern Europe, offi­cials did the pru­dent thing and can­celed all flights. They wanted to avoid a repeat of the near crash of a Boe­ing 747 in 1989. […]

Given the lim­ited amount of infor­ma­tion, anchor­ing to this pre­vi­ous event (and try­ing to avoid a worst case sce­nario) was the only rea­son­able reac­tion. The prob­lems began, how­ever, when these ini­tial beliefs about the risk of the ash cloud proved resis­tant to sub­se­quent updates. […]

My point is absolutely not that the ash cloud wasn’t dan­ger­ous, or that the avi­a­tion agen­cies were wrong to can­cel thou­sands of flights, at least ini­tially. […] Instead, I think we sim­ply need to be more aware that our ini­tial beliefs about a cri­sis — those opin­ions that are most shrouded in igno­rance and uncer­tainty — will exert an irra­tional influ­ence on our sub­se­quent actions, even after we have more (and more reli­able) infor­ma­tion. The end result is a kind of epis­temic stub­born­ness, in which we’re irra­tionally anchored to an out­moded assumption.

The same thing hap­pened with the BP oil spill.