Penny and Kahle (1996) points out that consumers, when interviewed, would state what they think they want but would behave in a different manner in 'real life'. This is especially true with the application of 'operant conditioning'. The term 'operant conditioning' as applied in marketing refers to the methods used by marketers to influence consumers to purchase or consume a product and make it look rewarding to the consumer. Coupons, repeated advertisements, free samples and other promotional gimmicks can and do influence consumer preference. Marketers can also employ different kind of appeals to endeavor a product to a consumer. Appeals include fear appeals, comparative appeals, emotional appeals, value expressive and utilitarian appeals all of which perform to make the customer want the product or service offered. The point is that there are many factors which can change what the consumer would want.
Another risk in relying on what the consumers say they want is that it can change over time and the time span can be radical or sporadic. For example, Greenwald (2003) conducted a study on the behavioral shift of UK consumers belonging to the 16-24 age bracket and found that some preference or attitudes change as fast as 3 days or as long as 5 years.
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