Some Psychological Context for Evidence

Evidence based decisions.  A mantra that gets used widely.  But there is of course a balance in decisions between evidence and judgement.  Decisions are easy, good decisions are more difficult, as they rely on getting that balance right between evidence and judgement.  But it does not stop there.

The reality of the world is that the evidence is set in the context of individual and social behaviours, which it can be easy to overlook.  The psychologists and sociologists have articulated and categorised plentiful behaviours that influence us both personally and collectively.  That adds another layer of challenge to power of evidence.

Here's just a few of those psychological contexts...

Cognitive Dissonance.  This is all about self perpetuating perspectives.  Where something is counter to a prevailing view (cognitive consistency), there are tendencies to find ways to assimilate those contradictions.  (Leon Festinger 1919-1989).  So the remedial action can typically include decreasing the perceived importance of the dissonance.  Dissonance can also be designed out....only taking information or news from specific sources for example.

Groupthink.  Really just cognitive dissonance for groups.  Coined in 1971, this describes the mutual reinforcement of group behaviour, often demonstrated as a general collective over confidence.   

False Memory.   Memories may not always be real.  They can be a distorted recollection or entirely imaginary.  So where memory is incomplete, the gaps can be filled with other information from other circumstances.  Entire false memory can be quite easily induced in experiments, often through mis-information.

Invisible Gorilla.  This about missing something obvious by being so focussed on something else.  In an experiment, a person in a gorilla suit (or dressed as a ghost or on a unicylce) walks through as baseball game and goes unnoticed by half of the spectators who have been briefed to count the number of passes.   More interestingly perhaps, even expecting the unexpected doesn't help you see it.

Halo Effect. Where one positive trait or outcome can lead to the assumption that other traits or outcomes are positive.    It works the other way around too as the "Horns Effect".  Its a long standing cognitive short cut for dealing lots of complex or missing data.

Muller-Lyer Illusion.  This is about the influence of visual context, especially important with the ever increasing infograhics and visualisations.  This is where the same two lines will seem to be of different lengths depending on their immediate visual context (typcially inward or outward facing arrows at each end).  The lines with the inward facing arrows will seem shorter, due to visual conditioning around perspective. 

Barnham Effect.  Named after the US Showman P.T. Barnum (1810-91), this describes statements which on the surface appear detailed or specific, but in fact will be vague or ambiguous, and even self contradictory and hence widely applicable as it covers all angles....Barnam described it as "having a little something for everyone".

Sources: Freudian Slips. Joel Levy. 2013