Yes, they do:
Seven experiments with 426 adolescents, undergraduates, and adults were conducted to examine the effectiveness of a compliance procedure known as the that’s-not-all technique. The procedure involves offering a product at a high price, not allowing the customer to respond for a few seconds, then offering a better deal by either adding another product or lowering the price. Exps I–II demonstrated the effectiveness of this procedure over a control group that was given the better deal initially. Exps III–IV suggested that this effectiveness may be partially explained through a norm of reciprocity that calls for the customer to respond to the seller’s new offer. Exp V suggested that the effect also results from an altering of the anchor point Ss use to judge the new price. Exp VI indicated the effectiveness of the procedure cannot be explained by the S perceiving the lower price as a bargain. Exp VII, which examined the differences between the that’s-not-all and the door-in-the-face procedures, implied that the former technique is more effective than the latter. Overall findings demonstrate the effectiveness of the that’s-not-all technique.
Source: “Increasing compliance by improving the deal: The that’s-not-all technique.” from Journal of Personality and Social Psychology, Vol 51(2), Aug 1986, 277-283.
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