Don't remember how much you paid? Blame card transaction

The chances are less as researchers have found that customers who pay for their purchases by card are less likely to remember the precise amount paid as compared to those who make cash transactions.

The findings, published in the journal Marketing Letters, apply to both single-function cards that offer only a payment function and multifunctional, or smart cards which may also include bonus programmes, user identification or other functions.

The research assumes significance in view of the fact that a precise recollection of past spending has an effect on the willingness to spend money in the future, the researchers explained.

It is estimated that approximately three billion new smart cards will be issued across the globe by 2017.

Smart cards combine the payment function with additional functionalities that can be directly governed through our smartphones or smart watches in the near future, the researchers noted.

"We wanted to show that individuals who pay by card have a less accurate recall of the amount paid than individuals who settle their bill with cash," said Rufina Gafeeva from the University of Cologne in Germany.

"Individuals who use the non-payment functions of the multifunctional card are less likely to remember the transaction details accurately."

The researchers interviewed 496 college students over their payment methods, initially before the introduction of multifunctional cards within the cafeterias and the second time, when smart cards were introduced one year later.

The results showed how such shifting methods of payment from cash to smart cards are affecting the customers.