Firstly the term ‘heuristic’ simply means a method (usually informal) that helps to solve a problem or put another way a method of disambiguation of an issue.
The Representative Heuristic was initially used by Kahneman & Tversky (1973) to describe a phenomenon they discovered whilst conducting research into how people make judgements when they are in ambiguous or uncertain territory. What they discovered is that frequently people will look for and find similarities between two events or objects and then make an assumption that the similarity they have discovered represents a rule and then apply that rule to create a solution. People look for a likely (to them) explanation to a problem based on similarities they think exist between a few bits of data and then make this similarity representative of that relationship, in other words it becomes a rule. However it doesn’t end there because when people do this they believe the representation that they have constructed assuming that it is correct.
You can try out a modern version of the original Kahneman & Tversky experiment here.
I came across a more common every day example last year:
I was conducting some research in a company and was working with a group of managers, one of whom was in the middle of recruiting for a post in his team. I was invited to observe some of the interviews. About 20 minutes before the next interview the manager received a call on his mobile. He listened for a second, said "thanks", closed the call and leapt up saying to me "come on, this is where I find out if it worth interviewing the next candidate". We both rushed to the window which overlooked the company cap park.
“There he is in the Silver car just coming through the barrier – let’s see what he does.”
The car then slowly navigated the car park looking for a space.
“We ask visitors to park over there” he said pointing at a few empty spaces marked ‘visitors only’. “Which is really handy as I can see what they are doing.”
The silver car moved to the spaces for visitors and drove straight into one of the available spaces. The car door then opened and a smartly dressed young man got out.
“At last, that’s the first one this week! Someone worth interviewing finally”
“Sorry?” I replied “I don’t understand.”
“Look” The manager explained “People who are focussed on work drive straight into their spaces. Everyone else has backed in this week. That means that they are more concerned with leaving than arriving, so I won’t hire them, no matter how good their CV is.”
Representative heuristics can be very useful in solving some problems. However because the logic used to construct a representative heuristic is often of the common sense variety they are frequently very misleading and plausible (I have had a number of people who I have told this story to say they hadn’t thought about it but now you mention it there must be something in it).
The other problem with this phenomenon is that it is also the basis for bigoted thinking. All women are, all blacks are, all homosexuals are, all engineers are... (Kahneman & Tversky )...and so on. One instance represents the similarities that the person has noticed (or more properly, constructed) and it is now considered to be true. Every time we now look at the situation having constructed the representation we keep noticing (filtering for) the same patterns of similarity and ignoring any differences.
Importantly it is worth noting is that this phenomenon is more likely to be used in new and ambiguous situations. Further in situations that evoke fear, like unwanted change and loss, the representations created are frequently to show just how negative this situation really is and to filter out positives and opportunities. That helps then!