Overcoming Bias: Scarcity

What follows is taken primarily from Robert Cialdini's Influence: The Psychology of Persuasion.  I own three copies of this book, one for myself, and two for loaning to friends.

Scarcity, as that term is used in social psychology, is when things become more desirable as they appear less obtainable.

• If you put a two-year-old boy in a room with two toys, one toy in the open and the other behind a Plexiglas wall, the two-year-old will ignore the easily accessible toy and go after the apparently forbidden one.  If the wall is low enough to be easily climbable, the toddler is no more likely to go after one toy than the other.  (Brehm and Weintraub 1977.)
   
• When Dade County forbade use or possession of phosphate detergents, many Dade residents drove to nearby counties and bought huge amounts of phosphate laundry detergents.  Compared to Tampa residents not affected by the regulation, Dade residents rated phosphate detergents as gentler, more effective, more powerful on stains, and even believed that phosphate detergents poured more easily.  (Mazis 1975, Mazis et. al. 1973.)
  

Similarly, information that appears forbidden or secret, seems more important and trustworthy:

• When University of North Carolina students learned that a speech opposing coed dorms had been banned, they became more opposed to coed dorms (without even hearing the speech).  (Probably in Ashmore et. al. 1971.)
   
• When a driver said he had liability insurance, experimental jurors awarded his victim an average of four thousand dollars more than if the driver said he had no insurance.  If the judge afterward informed the jurors that information about insurance was inadmissible and must be ignored, jurors awarded an average of thirteen thousand dollars more than if the driver had no insurance.  (Broeder 1959.)
   
• Buyers for supermarkets, told by a supplier that beef was in scarce supply, gave orders for twice as much beef as buyers told it was readily available.  Buyers told that beef was in scarce supply, and furthermore, that the information about scarcity was itself scarce - that the shortage was not general knowledge - ordered six times as much beef.  (Since the study was conducted in a real-world context, the information provided was in fact correct.)  (Knishinsky 1982.)

Overcoming Bias: Scarcity

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