The future is risky: discounting of delayed and uncertain outcomes.

The world is full of choices where outcomes are both delayed and probabilistic. Whilst the delay discounting framework provides a platform for examining the relationship between dimensions of time and probability, the majority of research has considered these factors in isolation, or made assumptions about their equivalence. In order to address these issues, we present a novel measurement approach for assessing the discounting of delayed and uncertain outcomes. We conducted two experiments which compared discounting on three types of delay discounting task (standard, uncertain outcome, and uncertain amount) and examined the robustness of using a delayed and uncertain outcome's certainty equivalent relative to its expected value as a method for measuring discount rates. Both experiments demonstrated that discounting is best modelled by a hyperbolic function that describes subjective values relative to their certain equivalents. Moreover, when modelled this way, clear differences emerged between the different aspects of uncertainty (outcome vs. amount) dependent on whether outcomes were delayed gains or losses. This was true for both group and individual delay discounting data, as well as for both outcomes that were uncertain with respect to whether they would occur or not and outcomes that were uncertain with respect to what their magnitude would be when they occurred.

Delay discounting as emotional processing: an electrophysiological study.

Both theoretical models and functional imaging studies implicate the involvement of emotions within the delay discounting process. However, defining this role has been difficult to establish with neuroimaging techniques given the automaticity of emotional responses. To address this, the current study examined electrophysiological correlates involved in the detection and evaluation of immediate and delayed monetary outcomes. Our results showed that modulation of both early and later ERP components previously associated with affective stimuli processing are sensitive to the signalling of delayed rewards. Together with behavioural reaction times that favoured immediacy, we demonstrated, for the first time, that time delays modify the incentive value of monetary rewards via mechanisms of emotional bias and selective visual attention. Furthermore, our data are consistent with the hypothesis that delayed and thus intangible rewards are perceived less saliently, and rely on emotion as a common currency within decision making. This study provides a new approach to delay discounting and highlights a potential novel route through which delay discounting may be investigated.

I want it now! Neural correlates of hypersensitivity to immediate reward in hypomania.

BACKGROUND: Hypomania is associated with impulsive decision making and risk taking, characteristics that may arise from hypersensitivity to reward. To date, the neural dynamics underlying intertemporal reward processing have neither been characterized clinically nor in the general population. Taking vulnerability to hypomania as a surrogate model of impulsivity, we utilized event-related potentials to study the neural mechanisms of delay discounting. METHODS: In the first experiment, 32 participants completed an established Two Choice Impulsivity Paradigm in which free choice between immediate and delayed rewards was used to quantify impulsivity behaviorally. In the second experiment, electroencephalography was recorded while 32 separately recruited participants completed a speeded response task involving gains and losses of monetary incentives to be paid at three different delays after the experiment. RESULTS: In the first experiment, the hypomania-prone group made significantly more immediate choices than the control group. In the second experiment, the hypomania-prone group evidenced greater differentiation between delayed and immediate outcomes in early attention-sensitive (N1) and later reward-sensitive (feedback-related negativity) components. Proneness to hypomania was also associated with greater N1 amplitude to rewards per se. CONCLUSIONS: These results indicate steeper delay discounting in hypomania at multiple stages of information processing. The N1 modulation by valence and delay suggests an attentional bias to immediate rewards, which may drive subsequent cognitive appraisal of outcomes (feedback-related negativity). These results highlight the early influence of attention on reward processing and provide support for reward dysregulation accounts of bipolar disorder. Potential implications for mindfulness training and other therapeutic interventions are highlighted.