The Availability Heuristic

   What is the availability heuristic? Tversky and
Kahneman (1973) proposed that people may use an
availability heuristic to judge frequency and the
probability of events.  Using the availability heuristic,
people would judge the probability of events by the ease in
which instances could be brought to mind.  Thus, using the
availability heuristic, people would judge an event to be
more likely to occur if they could think of more examples
of that event.  (1)

   Below are some examples of availability heuristic:

First Availabilty Heuristic Example

  After seeing many news stories of home foreclosures,
people may judge that the likelihood of this event is
greater.  This may be true because it is easier to think of
examples of this event.

Second Availabilty Heuristic Example

  People who read more case studies of successful
businesses may judge the probability of running a
successful business to be greater.


1.  One important question is how to define heuristics.  
Heuristics can be viewed as relatively simple rules to make
judgments and solve problems.  This is one heuristics


Tversky, A., & Kahneman, D.  (1973).   Availability:  A    
 heuristic for judging frequency and probability.
Cognitive Psychology, 5, 207-232.