A salesperson's attempts blatantly flatter customers in order to make a sale - for example, by fulsomely complimenting their dress sense or taste - can annoy the recipients. But it turns out the sweet words may still have a desirable effect. Customers, in the long term, harbour more positive views of the flatterer.

That was the finding in a study by Elaine Chan and Jaideep Sengupta of HKUST.

"Flattery is one of the oldest and most commonly used methods of persuasion and it has been shown to work because humans have a basic desire to believe in good things about themselves," they said.

"In situations where the flattery is clearly bogus, the recipient knows full well the flatterer is offering insincere compliments presumably with ulterior motives, other research and intuition suggest people will discount the flattering comments and correct their otherwise favourable reactions. What we found is that despite the correction, a positive impact of flattery may still be observed."

They looked at flattery from the perspective of explicit versus implicit attitudes. Explicit attitudes are consciously controlled by the individual and associated with discounting the flattery. Implicit attitudes are outside an individual's awareness and are automatically activated on exposure, in response to the feel-good factor of flattery. The latter were found to have staying power and be more influential in the long run in shaping a person's attitudes to the flatterer.

In one experiment, for instance, participants were shown a leaflet for a department store that contained flattering messages about their fashion sense, then had to evaluate the leaflet and the store. Some were told they had only five seconds to respond to each question - a constraint that evoked an implicit response - while others could take as long as they wanted, to evoke a reasoned, explicit response. The implicit group gave a far more positive evaluation of both the leaflet and the store's sincerity.

"The findings provide some interesting implications for marketing agents who use ingratiation as a persuasion tactic. They suggest that a relatively favourable implicit reaction co-exists along a corrected explicit reaction, rather than being replaced by it. This was observed despite the impersonal nature of the flattering communication [a store leaflet] and the presence of a clear ulterior motive,"the authors said.

The positive implicit attitude was also shown to affect behavior. In another experiment, participants did a similar exercise as above, then some were immediately offered a choice of a coupon for the flattering store or another from a store whose leaflet offered no flattery. This tapped into their explicit attitudes. The rest were asked to come back three days later and make the choice, when explicit attitudes would be less accessible and implicit ones more likely to dominate. As expected, the implicit conditions favoured the flattering store - after the delay, 80 per cent chose the coupon from the flattering store, against 54 per cent among those asked to choose immediately after viewing the leaflet.

In a third study, implicit attitudes were also found to make people more resistant to negative information about the flatterer - for instance, reading that the store had some adverse features (such as a restricted range of clothes; high prices, etc.) did not lower the positive implicit attitudes that had been created by flattery, although explicit attitudes did suffer. Interestingly, this experiment also showed how the insidious effects of flattery might be combated. The authors found that this could be done by making participants feel good about themselves (e.g., by writing about a positive trait of their own) even before they got the flattering communication from the store. These participants were not affected by flattery, as shown by their lower implicit evaluations of the store in comparison to those that had not engaged in the self-affirmation task prior to receiving the flattering communication.

Despite this caveat, the overall suggest that insincere compliments can have a persuasive influence on consumers, thus providing insights of practical applicability.

Although the flattery may have a negative impact in the short run, the implicit reaction will still be more influential in some ways than the corrected judgment, both with regard to delayed effects and in terms of withstanding an attack. This offers further room for optimism in marketing agents interested in using flattery as a persuasion device (while simultaneously being a cause for concern from the consumers viewpoint), the authors said.

However, the fact that the influence of flattery could be diminished through self-affirmation was a useful insight for combating the effects of flattery, and is something that consumers (and others interested in warding off persuasion attempts) can keep in mind.