A concurrent-choice analysis of amount-dependent temporal discounting

• Demonstrated amount-dependent temporal discounting with a concurrent-choice procedure.
• These findings were consistent with the matching law.
• This study confirms the cross-species generality of the magnitude effect.

Amount-dependent temporal discounting refers to the differential rates at which the values of large and small rewards are discounted over time. A lower rate of discounting of larger rewards is known as the magnitude effect. The present study aimed to establish a magnitude effect in humans using a concurrent-choice procedure. Participants indicated their strength of preference between hypothetical outcomes that differed in monetary value, and in the delay at which they were available. Most studies of temporal discounting measure preference using indifference points estimated from a titration procedure. The present study measured preference using a concurrent choice procedure. The main analysis demonstrated temporal discounting and a magnitude effect. Further analysis showed that the result was consistent with the matching law.