Tuesday 30 December 2014

Human Bias - Evaluation

When it comes to identification there may be a whole range of questions that need answering and these answers are rarely simple.  Anyone who studies biology will know that there can be great variation for any given trait.  Thus bird identification is complex and very often open to debate.  When it comes to evaluation of the evidence we clearly have a lot to consider.  It doesn't help that we can be distracted from our goal by inherent biases in our patterns of thought.

Some memory and availability biases in evaluating evidence
Some biases and heuristics are caused by recent memory.  Availability heuristic/recency bias are tendencies to overestimate the likelihood of events due to their greater availability in memory. Availability cascade is a reinforcing process where an idea gains credence simply by being repeated - 'if we say it enough we will eventually believe it'.  This can be an example of group think - eg. on a social forum.  Our memory can be subject to confirmation bias, where we tend to remember information in a way that confirms our preconceptions, possibly even ignoring or suppressing information that may be at odds with our conclusions. Sometimes if we have recently seen a word or object, all of a sudden it appears to be everywhere - we might imagine it's frequency has increased but really we are just more aware of it than before (frequency illusion/observation selection bias). Hindsight bias is the tendency to see past events as being predictable.  Distinction bias is a tendency to view two options as more dissimilar when viewed side by side than when evaluated separately.

Some belief biases in evaluating evidence
Regardless of the logic of an argument or the statistical probability behind it, we can be swayed by whether or not we actually believe it to be true or not (belief bias).  Selective perception is the tendency for expectation to affect perception. Sometimes we may be biased by how hard or easy an identification might appear (hard-easy effect).  Restraint bias is the tendency to overestimate one's ability to show restraint in the face of temptation.  Semmelweis reflex is the tendency to reject new evidence that contradicts a paradigm.  The zero-risk bias is a preference for reducing a small risk to zero over a greater reduction of a larger risk.  In terms of an identification based on a collection of variables I guess this might equate to spending too long on a fairly irrelevant part of the puzzle because it might be considered low hanging fruit (like unit bias - the tendency to want to complete a unit task).  Thereby we miss the bigger picture.  

Some biases in evaluating statistical probability
When faced with an image of a bird it is human nature to ask, is this species likely in this context.  Neglect of probability is a tendency to completely disregard probability when making a decision under uncertainty.  On the other hand, disregarding a possible answer due to low probability can also be problematic.  Some of us suffer from exaggerated expectation while others suffer conservatism or regressive bias - the tendency to underestimate high values and likelihoods while overestimating low ones.  Some people exhibit base rate fallacy, or the tendency to ignore the first choice.  People often see patterns in occurrences and draw conclusions though there may be no statistical significance (clustering illusion).  A gambler's fallacy is the tendency to think that future probabilities are altered by past events when in reality they are unchanged.  The illusion of validity is the belief that further acquired information generated additional relevant data for predictions, even when it evidently does not.  The subadditivity effect is the tendency to estimate that the liklihood of a remembered event is less than the sum of its (more than two) mutually exclusive components.

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