transaction value is zero. If the price is lower than the reference price, the transaction utility is positive. Total utility received from a transaction, then, is the sum of acquisition utility and transaction utility. Pain of Paying A more proximal psychological mechanism through which mental accounting influences spending is through its influence on the pain of paying that is associated with spending money from a mental account. Pain of paying is a negative affective response associated with a financial loss. Prototypical examples are the unpleasant feeling that one experiences when watching the fare increase on a taximeter or at the gas pump. When considering an expense, consumers appear to compare the cost of the expense to the size of an account that it would deplete (e.g., numerator vs. denominator). A $30 t-shirt, for example, would be a subjectively larger expense when drawn from $50 in one's wallet than $500 in one's checking account. The larger the fraction, the more pain of paying the purchase appears to generate and the less likely consumers are to then exchange money for the good. Other evidence of the relation between pain of paying and spending include the lower debt held by consumers who report experiencing a higher pain of paying for the same goods and services than consumers who report experiencing less pain of paying. Practical implications Psychology Mental accounting is subject to many logical fallacies and cognitive biases, which hold many implications such as overspending. Credit cards and cash payments Another example of mental accounting is the greater willingness to pay for goods when using credit cards than cash. If one uses a credit card to pay for tickets to a sporting event, they will tend to be willing to pay more than if they made their bid with cash. This phenomenon is also related to transaction decoupling, the separation of when a good is acquired and when it is actually paid for. Swiping a credit card prolongs the payment to a later date (when we pay our monthly bill) and it adds it to a large existing sum (our bill to that point). This delay causes the payment to stick in our memory less clearly and saliently. Furthermore, the payment is no longer perceived in isolation; rather, it is seen as a (relatively) small increase of an already large credit card bill. For example, it might be a change from $120 to