Unifying Evidence on Delay Discounting: Open Task, Analysis Tutorial, and Normative Data from an Italian Sample.

Area of Science:

• Neuroscience
• Behavioral Economics
• Psychology

Background:

• The delay discounting task is widely used but lacks standardization, hindering cross-study comparisons.
• A lack of normative data makes it difficult to interpret individual performance on delay discounting tasks.

Purpose of the Study:

• To propose a unified monetary delay discounting task.
• To provide normative values for this task using a healthy Italian sample.
• To identify the most valid index for discriminating between normative and clinical populations with impulsivity issues.

Main Methods:

• Developed a unified monetary delay discounting task.
• Collected data from 357 healthy Italian participants to establish normative values.
• Compared commonly used delay discount rate parameters to identify the most discriminative index, particularly for patients with medial orbitofrontal cortex (mOFC) lesions.

Main Results:

• mOFC patients exhibited significantly higher delay discounting scores compared to the normative sample.
• The study proposes using the 90th percentile for hyperbolic k or 10th percentile for AUC to identify extremely high delay discounting.
• Conversely, the 10th percentile for hyperbolic k or 90th percentile for AUC can identify extremely low delay discounting.

Conclusions:

• The proposed unified delay discounting task and its associated indexes are valuable tools for assessing impulsivity.
• The task and normative data can effectively differentiate between typical and atypical delay discounting behaviors, including those seen in mOFC patients.
• The study provides open-access data and code for broader research application and clinical use.