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            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. 

Notes

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 definition.


References

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