Sweet like chocolate
Free samples are often used as a compliance tactic to increase customer purchase rates. In 1991 Lammers conducted a lovely little study in a Los Angeles chocolate shop to investigate this effect. He asked the chocolatiers of Ethel M to give half of customers a free sample of their chocolate and carefully record if they made any purchases. The purchases from the other half of not so lucky customers were also documanted. The results showed that the free samples did indeed increase customer purchases. Customers who received a free sample were significantly more likely to then buy a product (perchance rate of 85%), compared to the customers who had not been sweetened by the sample (purchase rate of only 56%). The data also revealed that type of purchase after a free sample was not restricted to the variety of chocolate that they had tasted. Lammers suggested that this interesting finding may be caused by the attribution theory of stimulus saliency. This would predict that by trying a product, all of its associated cues are heightened such as taste and smell which, assuming that the experience was positive, helps to increase any product sales of this type.
Lammers, H. B. (1991). The effect of free samples on immediate consumer purchase. Journal of Consumer Marketing, 8(2), 31-37.