Impulsive people have a compulsion for immediate gratification-certain or uncertain

Abstract

Impulsivity has been defined as choosing the smaller more immediate reward over a larger more delayed reward. The purpose of this research was to gain a deeper understanding of the mental processes involved in the decision making. We examined participants' rates of delay discounting and probability discounting to determine their correlation with time-probability trade-offs. To establish the time-probability trade-off rate, participants adjusted a risky, immediate payoff to a delayed, certain payoff. In effect, this yielded a probability equivalent of waiting time. We found a strong, positive correlation between delay discount rates and the time-probability trade-offs. This means that impulsive people have a compulsion for immediate gratification, independent of whether the immediate reward is certain or uncertain. Thus, they seem not to be concerned with risk but rather with time.

Keywords: delay discounting; impulsivity; magnitude effect; probability discounting; sign effect; time-probability trade-off.

FIGURE 1

Median indifference points for various magnitudes (PLN 200 and PLN 5000) and signs of an outcomes (panel A: gains panel B: losses) in the time-probability trade-off [p(t)]. The indifference points represent an equilibrium between delay and probability: the subjective value of a delay is expressed as probability of outcome occurrence.

FIGURE 2

Mean subjective value expressed as averaged indifference points. All data are expressed as proportions. In case of time-probability trade-off the means can be interpreted in terms of probability, and in f(t) and f(p) conditions as a proportion of immediate/certain subjective value to larger later/certain reward. The panels refer to (standard deviations are presented in order gain PLN 200, gain PLN 5000, loss PLN 200, loss PLN 5000): (A) p(t)—probability-time trade-off (SDs respectively: 0.245, 0.205, 0.301, 0.254); (B) f(t)—delay discounting (SDs respectively: 0.236, 0.250, 0.289, 0.288); (C) f(p)—probability discounting conditions (SDs respectively: 0.181, 0.196, 0.225, 0.253).