Two-Step Decision Task

Technical Manual

Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond

Credits:
Millisecond thanks Dr. Nathaniel Daw for permission to publish this script in the Millisecond Test Library!

Millisecond thanks Dr. Nathaniel Daw for permission to publish this script
in the Millisecond Test Library!

Last Modified: January 12, 2025 by K. Borchert (katjab@millisecond.com), Millisecond

Script Copyright © Millisecond Software, LLC

Background

This script implements a batch script for the Two-step Decision task ('Alien Task') by Decker et al (2016). The Two-step Decision task is a child-friendly task to study decision making in children using a two-stage reinforcement learning task.

This batch script controls the assignment of 4 different payoff schedules by groupnumber assignment.

Subtest Manuals

Two-Step Decision Task ('Alien Task')

Two-Step Decision Task ('Alien Task')

Two-Step Decision Task ('Alien Task')

Two-Step Decision Task ('Alien Task')

References

Decker JH, Otto AR, Daw ND, Hartley CA. From Creatures of Habit to Goal-Directed Learners: Tracking the Developmental Emergence of Model-Based Reinforcement Learning. Psychol Sci. 2016 Jun;27(6):848-58. doi: 10.1177/0956797616639301. Epub 2016 Apr 15. PMID: 27084852; PMCID: PMC4899156.

Duration

25 minutes

Description

Decision Step 1: Participants are asked to select btw two spaceships that travel to two planets with different probabilities (e.g. spaceship1 travels to planet1 with p = 0.7 and to planet2 with p = 0.3).

Decision Step 2: On each planet, they encounter two aliens that work in mines. Aliens retrieve treasure with 'drifting' probabilities. Participants are asked to select one of the aliens. If the selected alien happens to retrieve treasure from the mine, it shares it with the participant.

The goal is to collect as much treasure as possible.