README.md

In bramzandbelt/itchmodel: Cognitive model of time framing effects in intertemporal choice

itchmodel - Intertemporal choice model

Overview

itchmodel is a computational model that can be used to understand the cognitive mechanisms underlying intertemporal choice performance: the defer/speedup effect (also known as the delay/speedup effect) and the date/delay effect.

The model builds on two tradeoff models of intertemporal choice: one that explains choice probabilities and full response time distributions in intertemporal choice Dai & Busemeyer, 2014 and another that can account for contextual effects, such as framing of time Scholten & Read, 2013.

Description

Conceptually, the model explains intertemporal choice as a three-step process:

1. A decision maker transforms money into utility (value function), and calendar time into perceived/weighted time (time function), separately for the small-but-sooner and large-but-later options. These value and time functions are governed by power transformations.

2. Differences in utility are compared against differences in perceived/weighted time with different weights (w scales the difference between weighted delays and the difference between valued outcomes in a common currency), resulting in d, the overall advantage of the large-but-later option over the small-but-sooner option.

3. The mean rate of preference, d, is accumulated over time to a threshold that triggers an explicit preferential choice (i.e. diffusion or sequential-sampling process), providing predicted choice and response time.

The current version of the model can be parameterized in multiple ways to explain context effects, such as time framing:

1. Parameter mu varies between frames, corresponding to the hypothesis that time framing influences valuation.

2. Parameter kappa varies between frames, corresponding to the hypothesis that time framing influences time weighting/perception.

3. Parameters mu and kappa vary between frames, corresponding to the hypothesis that time framing influences both valuation and time weighting/perception.

4. Parameters mu and t0 vary between frames; as 1., but also explaining RT differences due to differences in stimuli.

5. Parameters kappa and t0 vary between frames; as 2., but also explaining RT differences due to differences in stimuli.

6. Parameters mu, kappa, and t0 vary between frames; as 3., but also explaining RT differences due to differences in stimuli.

Installation

The model can be installed from R as follows:

devtools::install_github("bramzandbelt/itchmodel")
library(itchmodel)

Usage

Usage will be explained in more detail soon. In the meantime, see the R Markdown notebooks inside the analysis directory for usage examples.

Colophon

Version

0.0.1 - June 2018

Contact

E-mail: [e-mail]

References

• Scholten, M. & Read, D. (2013) Time and outcome framing in intertemporal tradeoffs. Journal of Experimental Psychology: Learning, Memory, and Cognition, 39, 1192–1212.

• Dai, J. & Busemeyer, J.R. (2014) A probabilistic, dynamic, and attribute-wise model of intertemporal choice. Journal of Experimental Psychology: General, 143, 1489–1514.

bramzandbelt/itchmodel documentation built on May 7, 2019, 8:42 a.m.