Help for package tempodisco

Type:

Package

Title:

Temporal Discounting Models

Description:

Tools for working with temporal discounting data, designed for behavioural researchers to simplify data cleaning/scoring and model fitting. The package implements widely used methods such as computing indifference points from adjusting amount task (Frye et al., 2016, <doi:10.3791/53584>), testing for non-systematic discounting per the criteria of Johnson & Bickel (2008, <doi:10.1037/1064-1297.16.3.264>), scoring questionnaires according to the methods of Kirby et al. (1999, <doi:10.1037//0096-3445.128.1.78>) and Wileyto et al (2004, <doi:10.3758/BF03195548>), Bayesian model selection using a range of discount functions (Franck et al., 2015, <doi:10.1002/jeab.128>), drift diffusion models of discounting (Peters & D'Esposito, 2020, <doi:10.1371/journal.pcbi.1007615>), and model-agnostic measures of discounting such as area under the curve (Myerson et al., 2001, <doi:10.1901/jeab.2001.76-235>) and ED50 (Yoon & Higgins, 2008, <doi:10.1016/j.drugalcdep.2007.12.011>).

Author:

Isaac Kinley [aut, cre]

Maintainer:

Isaac Kinley <isaac.kinley@gmail.com>

License:

GPL-3

Version:

2.1.0

RoxygenNote:

7.3.3

Encoding:

UTF-8

Depends:

R (≥ 3.5.0)

Imports:

stats, graphics, methods, grDevices, RWiener

Suggests:

knitr, rmarkdown, testthat

Config/testthat/edition:

VignetteBuilder:

knitr

URL:

https://kinleyid.github.io/tempodisco/

BugReports:

https://github.com/kinleyid/tempodisco/issues

NeedsCompilation:

Packaged:

2026-03-07 15:05:39 UTC; isaac

Repository:

CRAN

Date/Publication:

2026-03-12 08:00:02 UTC

tempodisco: Temporal Discounting Models

Description

Tools for working with temporal discounting data, designed for behavioural researchers to simplify data cleaning/scoring and model fitting. The package implements widely used methods such as computing indifference points from adjusting amount task (Frye et al., 2016, doi:10.3791/53584), testing for non-systematic discounting per the criteria of Johnson & Bickel (2008, doi:10.1037/1064-1297.16.3.264), scoring questionnaires according to the methods of Kirby et al. (1999, doi:10.1037//0096-3445.128.1.78) and Wileyto et al (2004, doi:10.3758/BF03195548), Bayesian model selection using a range of discount functions (Franck et al., 2015, doi:10.1002/jeab.128), drift diffusion models of discounting (Peters & D'Esposito, 2020, doi:10.1371/journal.pcbi.1007615), and model-agnostic measures of discounting such as area under the curve (Myerson et al., 2001, doi:10.1901/jeab.2001.76-235) and ED50 (Yoon & Higgins, 2008, doi:10.1016/j.drugalcdep.2007.12.011).

Author(s)

Maintainer: Isaac Kinley isaac.kinley@gmail.com

Area under the curve (AUC)

Description

Compute either the model-based or model-free area under the curve.

Usage

AUC(
  obj,
  min_del = 0,
  max_del = NULL,
  val_del = NULL,
  del_transform = c("none", "log", "ordinal-scaling"),
  ...
)

Arguments

obj

A temporal discounting model or a dataframe with columns indiff (indifference point) and del (delay).

min_del

Lower limit to use for integration. Defaults to 0.

max_del

Upper limit to use for integration. Defaults to the maximum delay in the data.

val_del

Delayed value to use for computing the indifference curve, if applicable. Defaults to the average del_val in the data.

del_transform

String specifying transformation to apply to the delays (e.g., log10 + 1 transform or ordinal scaling transform; Borges et al., 2016, doi:10.1002/jeab.219). Default is no transform.

...

Further arguments passed to 'integrate()'.

Value

AUC value.

Note

An indifference point of 1 is assumed at delay 0.

Examples


data("td_bc_single_ptpt")
mod <- td_bcnm(td_bc_single_ptpt, discount_function = "exponential")
print(AUC(mod))

Median effective delay

Description

Compute the median effective delay.

Usage

ED50(mod, val_del = NULL)

Arguments

mod

A temporal discounting model.

val_del

Delayed value, if applicable (i.e., if magnitude effects are accounted for).

Value

Median effective delay value.

Examples


data("td_bc_single_ptpt")
mod <- td_bcnm(td_bc_single_ptpt, discount_function = "exponential")
print(ED50(mod))

Indifference points from adjusting amount procedure

Description

Compute indifference points for data from an adjusting amount procedure (also called a "titrating procedure").

Usage

adj_amt_indiffs(data, block_indic = "del", order_indic = NULL)

Arguments

data

A dataframe where each row corresponds to a binary choice, with at least columns val_imm, val_del, and imm_chosen, along with a block indicator and (if applicable) an order indicator.

block_indic

Column name of the block indicator—i.e., the column that will identify a block of trials for which an indifference point should be computed. If unspecified, defaults to 'del', which assumes that each block corresponds to a different delay.

order_indic

Column name of the order indicator—i.e., the column that specifies the order in which trials were completed. Sorting by this column within a block should sort the rows in chronological order. If unspecified, the rows are assumed to already be in chronological order.

Value

A dataframe with two columns: one for the block indicator and another for the corresponding indifference point.

Examples


data("adj_amt_sim")
adj_amt_indiffs(adj_amt_sim)
adj_amt_indiffs(adj_amt_sim, block_indic = 'del', order_indic = 'trial_idx')

Simulated adjusting amount procedure

Description

A minimal example of data from a single participant for an adjusting amount procedure.

Author(s)

Isaac Kinley isaac.kinley@gmail.com

Test for failed attention checks

Description

Check whether participants failed attention checks, either choosing an immediate reward of 0 or choosing a delayed reward equal in face value to an immediate reward. If the participant was never offered either choice, a warning is given.

Usage

attention_checks(data, warn = FALSE, ppn = FALSE)

Arguments

data

A data.frame with columns val_imm, val_del and del_chosen, representing data from a single participant.

warn

Logical: give a warning for failed attention checks?

ppn

Logical: return proportions of attention checks participant failed, versus absolute numbers?

Value

Named vector counting the number of times the participant chose an immediate reward of 0 (imm_0) or chose a delayed reward equal in face value to an immediate reward (del_eq_imm).

Examples


# On a model
data("td_bc_single_ptpt")
attention_checks(td_bc_single_ptpt)

Extract model coefficients

Description

Get coefficients of a temporal discounting binary choice linear model.

Usage

## S3 method for class 'td_bclm'
coef(object, df_par = TRUE, ...)

Arguments

object

An object of class td_bcnm.

df_par

Boolean specifying whether the coefficients returned should be the parameters of a discount function (versus the beta parameters from the regression).

...

Additional arguments currently not used.

Value

A named vector of coefficients.

Extract model coefficients

Description

Get coefficients of a temporal discounting binary choice nonlinear model.

Usage

## S3 method for class 'td_bcnm'
coef(object, ...)

Arguments

object

An object of class td_bcnm.

...

Additional arguments currently not used.

Value

A named vector of coefficients.

Extract model coefficients

Description

Get coefficients of a temporal discounting drift diffusion model.

Usage

## S3 method for class 'td_ddm'
coef(object, type = "all", ...)

Arguments

object

An object of class td_ddm.

type

A string specifying which coefficients to extract. 'all' extracts them all, 'ddm' extracts only DDM-specific parameters, and 'df' extracts only discount function parameters.

...

Additional arguments currently not used.

Value

A named vector of coefficients.

Extract model coefficients

Description

Get coefficients of a temporal discounting indifference point model.

Usage

## S3 method for class 'td_ipm'
coef(object, ...)

Arguments

object

An object of class td_ipm

...

Additional arguments currently not used.

Value

A named vector of coefficients.

Model deviance

Description

Compute deviance for a temporal discounting binary choice model.

Usage

## S3 method for class 'td_bcnm'
deviance(object, ...)

Arguments

object

An object of class td_bcnm.

...

Additional arguments currently not used.

Value

The value of the deviance extracted from the model

Model deviance

Description

Compute deviance for a temporal discounting drift diffusion model.

Usage

## S3 method for class 'td_ddm'
deviance(object, ...)

Arguments

object

An object of class td_ddm.

...

Additional arguments currently not used.

Value

The value of the deviance extracted from the model

Get discount function from model

Description

Access the name of the discount function of a model.

Usage

discount_function(mod)

Arguments

mod

A temporal discounting model.

Value

The name of the discount function.

Examples


data("td_bc_single_ptpt")
mod <- td_bcnm(td_bc_single_ptpt, discount_function = "exponential")
discount_function(mod)

Get fitted values

Description

Get fitted values of a temporal discounting binary choice model.

Usage

## S3 method for class 'td_bcnm'
fitted(object, ...)

Arguments

object

An object of class td_bcnm.

...

Additional arguments currently not used.

Value

A named vector of fitted values.

Get fitted values

Description

Get fitted values of a temporal discounting drift diffusion model.

Usage

## S3 method for class 'td_ddm'
fitted(object, ...)

Arguments

object

An object of class td_ddm.

...

Additional arguments currently not used.

Value

A named vector of fitted values.

Get fitted values

Description

Get fitted values of a temporal discounting indifference point model.

Usage

## S3 method for class 'td_ipm'
fitted(object, ...)

Arguments

object

An object of class td_ipm.

...

Additional arguments currently not used.

Value

A named vector of fitted values.

Get all available pre-defined discount functions

Description

Get a list of all of the available pre-defined discount functions.

Usage

get_available_discount_functions()

Value

A character vector containing the names of the avialable pre-defined discount functions.

Examples


get_available_discount_functions()

Get model-free indifference points

Description

Convert a temporal discounting model with the "model-free" discount function to a dataframe of indifference points.

Usage

indiffs(mod)

Arguments

mod

A model of class td_bcnm, td_ipm, or td_ddm for which the "model-free" discount function has been fit.

Value

A dataframe with columns del (delay) and indiff (indifference point).

Examples


data("td_bc_single_ptpt")
mod <- td_bcnm(td_bc_single_ptpt, discount_function = 'model-free')
indiff_data <- indiffs(mod)

Check for invariant responding

Description

Check whether participants always chose the immediate reward or always chose the delayed reward.

Usage

invariance_checks(data, warn = FALSE)

Arguments

data

A data.frame with columns val_imm, val_del and del_chosen, representing data from a single participant.

warn

Logical: give a warning for invariant responding?

Value

Named vector specifying whether the participant chose only immediate rewards (all_imm) or chose all delayed rewards (all_del).

Examples


# On a model
data("td_bc_single_ptpt")
attention_checks(td_bc_single_ptpt)

Compute consistency score

Description

Compute the consistency score per the method of Kirby et al. (1999, doi:10.1037//0096-3445.128.1.78). This is described in detail in Kaplan et al. (2016, doi:10.1007/s40614-016-0070-9), where it's suggested that a consistency score below 0.75 might be a sign of inattentive responding.

Usage

kirby_consistency(
  data,
  discount_function = c("hyperbolic", "exponential", "power", "arithmetic")
)

Arguments

data

Responses to score.

discount_function

Should k values be computed according to the hyperbolic, exponential, power, or arithmetic discount function? The original method uses the hyperbolic, but in principle any single-parameter discount function can also be used (though these should be considered experimental features).

Value

A consistency score between 0 and 1.

Examples


data("td_bc_single_ptpt")
mod <- kirby_consistency(td_bc_single_ptpt)

Kirby MCQ-style scoring

Description

Score a set of responses according to the method of Kirby et al. (1999, doi:10.1037//0096-3445.128.1.78). This is described in detail in Kaplan et al. (2016, doi:10.1007/s40614-016-0070-9).

Usage

kirby_score(
  data,
  discount_function = c("hyperbolic", "exponential", "power", "arithmetic")
)

Arguments

data

Responses to score.

discount_function

Should k values be computed according to the hyperbolic, exponential, or power discount function? The original method uses the hyperbolic, but in principle the exponential and power are also possible (though these should be considered experimental features).

Value

An object of class td_ipm.

Examples


data("td_bc_single_ptpt")
mod <- kirby_score(td_bc_single_ptpt)

Extract log-likelihood

Description

Compute log-likelihood for a temporal discounting binary choice nonlinear model.

Usage

## S3 method for class 'td_bcnm'
logLik(object, ...)

Arguments

object

An object of class td_bcnm

...

Additional arguments currently not used.

Value

Returns an object of class logLik with attributed df and nobs

Extract log-likelihood

Description

Compute log-likelihood for a temporal discounting drift diffusion model.

Usage

## S3 method for class 'td_ddm'
logLik(object, type = c("resp_rt", "resp", "rt"), ...)

Arguments

object

An object of class td_bcnm.

type

Should probabilities /probability densities be computed for responses and RTs ('resp_rt', default) or responses only ('resp')?

...

Additional arguments currently not used.

Value

Returns an object of class logLik with attributed df and nobs

Extract log-likelihood

Description

Compute log-likelihood for a temporal discounting indifference point model.

Usage

## S3 method for class 'td_ipm'
logLik(object, ...)

Arguments

object

An object of class td_ipm

...

Additional arguments currently not used.

Value

Returns an object of class logLik with attributed df and nobs

Experimental method for computing indifference points

Description

Experimental method for computing indifference points

Usage

most_consistent_indiffs(data)

Arguments

data

Responses to score.

Value

A dataframe with two columns: one for the block indicator and another for the corresponding indifference point.

Check for non-systematic discounting

Description

Check for non-systematic discounting, per the Johnson & Bickel (2008) criteria. These are:

C1: No indifference point can exceed the previous by more than 0.2
C2: Last indifference point must be lower than first by at least 0.1

Usage

nonsys(obj)

Arguments

obj

Either a data.frame with columns indiff and del, or a discounting model of class td_bcnm or td_ipm, fit using the "model-free" discount function.

Value

Named logical vector specifying whether nonsystematic discounting is exhibited according to C1/C2.

Examples


# On a model
data("td_bc_single_ptpt")
mod <- td_bcnm(td_bc_single_ptpt, discount_function = 'model-free')
any(nonsys(mod))

# On a dataframe
data("td_ip_simulated_ptpt")
any(nonsys(td_ip_simulated_ptpt))

# Artificial case of nonsystematic discounting
nonsys(data.frame(del = 1:3, indiff = c(0.5, 0.8, 0.6))) # Both TRUE

Plot models

Description

Plot delay discounting models.

Usage

## S3 method for class 'td_um'
plot(
  x,
  type = c("summary", "endpoints", "link", "rt"),
  legend = TRUE,
  p_lines = NULL,
  p_tol = 0.001,
  verbose = TRUE,
  del = NULL,
  val_del = NULL,
  q_lines = c(0.025, 0.975),
  ...
)

Arguments

x

A delay discounting model. See dd_prob_model and dd_det_model.

type

Type of plot to generate.

legend

Logical: display a legend? Only relevant for type = 'summary' and type = 'rt'.

p_lines

Numerical vector. When type = 'summary' the discount curve, where the probability of selecting the immediate reward is 0.5, is plotted. p_lines allows you to specify other probabilities for which similar curves should be plotted (only applicable for probabilistic models, e.g. td_bcnm, td_bclm and td_ddm).

p_tol

If p_lines is not NULL, what is the maximum distance that estimated probabilities can be from their true values? Smaller values results in slower plot generation.

verbose

Whether to print info about, e.g., setting del = ED50 when type = 'endpoints'.

del

Plots data for a particular delay.

val_del

Plots data for a particular delayed value.

q_lines

When type = 'rt', plot dashed lines for which quantiles of the predicted RT distribution? Default is 0.025 and 0.975 (i.e., a quantile-based 95% confidence interval).

...

Additional arguments to plot().

Value

No return value (called to produce a plot)

Examples


data("td_bc_single_ptpt")
mod <- td_bclm(td_bc_single_ptpt, model = 'hyperbolic.1')
plot(mod, type = 'summary', p_lines = c(0.25, 0.75), log = 'x')
plot(mod, type = 'endpoints')

Model Predictions

Description

Generate predictions from a temporal discounting binary choice linear model.

Usage

## S3 method for class 'td_bclm'
predict(
  object,
  newdata = NULL,
  type = c("indiff", "link", "response", "terms"),
  ...
)

Arguments

object

A temporal discounting binary choice linear model. See td_bclm.

newdata

Optionally, a data frame to use for prediction. If omitted, the data used to fit the model will be used for prediction.

type

The type of prediction required. For 'indiff' (default) gives predicted indifference points. In this case, newdata needs only a del column. For all other values (e.g. "link", "response"), this function is just a wrapper to predict.glm().

...

Additional arguments passed to predict.glm if type != 'indiff'.

Value

A vector of predictions.

Examples


data("td_bc_single_ptpt")
mod <- td_bclm(td_bc_single_ptpt, model = 'hyperbolic.1')
indiffs <- predict(mod, newdata = data.frame(del = 1:100), type = 'indiff')

Model Predictions

Description

Generate predictions from a temporal discounting binary choice model.

Usage

## S3 method for class 'td_bcnm'
predict(object, newdata = NULL, type = c("link", "response", "indiff"), ...)

Arguments

object

A temporal discounting binary choice model. See td_bcnm.

newdata

Optionally, a data frame to use for prediction. If omitted, the data used to fit the model will be used for prediction.

type

The type of prediction required. As in predict.glm, "link" (default) and "response" give predictions on the scales of the linear predictors and response variable, respectively. "indiff" gives predicted indifference points. For predicting indifference points, newdata needs only a del column.

...

Additional arguments currently not used.

Value

A vector of predictions.

Examples


data("td_bc_single_ptpt")
mod <- td_bcnm(td_bc_single_ptpt, discount_function = 'hyperbolic')
indiffs <- predict(mod, newdata = data.frame(del = 1:100), type = 'indiff')

Model Predictions

Description

Generate predictions from a temporal discounting drift diffusion model.

Usage

## S3 method for class 'td_ddm'
predict(
  object,
  newdata = NULL,
  type = c("indiff", "link", "response", "rt"),
  ...
)

Arguments

object

A temporal discounting drift diffusion model. See td_ddm.

newdata

Optionally, a data frame to use for prediction. If omitted, the data used to fit the model will be used for prediction.

type

...

Additional arguments currently not used.

Value

A vector of predictions.

Note

When type = 'rt', expected RTs are computed irrespective of which reward was selected, per equation 5 in Grasman, Wagenmakers, & van der Maas (2009, doi:10.1016/j.jmp.2009.01.006).

Examples


data("td_bc_single_ptpt")
ddm <- td_ddm(td_bc_single_ptpt, discount_function = 'exponential',
              gamma_par_starts = 0.01,
              beta_par_starts = 0.5,
              alpha_par_starts = 3.5,
              tau_par_starts = 0.9)
pred_rts <- predict(ddm, type = 'rt')

Model Predictions

Description

Generate predictions from a temporal discounting indifference point model

Usage

## S3 method for class 'td_ipm'
predict(object, newdata = NULL, type = c("indiff", "response"), ...)

Arguments

object

A temporal discounting indifference point model. See td_ipm.

newdata

A data frame to use for prediction. If omitted, the data used to fit the model will be used for prediction.

type

Type of prediction, either 'indiff' (indifference points) or 'response' (whether the participants would is predicted to choose the immediate (1) or delayed reward (0)).

...

Additional arguments currently not used.

Value

A vector of predictions.

Examples


data("td_ip_simulated_ptpt")
mod <- td_ipm(td_ip_simulated_ptpt, discount_function = 'hyperbolic')
indiffs <- predict(mod, del = 1:100)
indiffs <- predict(mod, newdata = data.frame(del = 1:100))

Residuals from temporal discounting model

Description

Get residuals from a temporal discounting binary choice nonlinear model.

Usage

## S3 method for class 'td_bcnm'
residuals(object, type = c("deviance", "pearson", "response"), ...)

Arguments

object

A temporal discounting binary choice model. See td_bcnm.

type

The type of residuals to be returned. See residuals.glm.

...

Additional arguments currently not used.

Value

A vector of residuals.

Residuals from temporal discounting model

Description

Get residuals from a temporal discounting indifference point model.

Usage

## S3 method for class 'td_ipm'
residuals(object, type = c("response", "pearson"), ...)

Arguments

object

A temporal discounting model. See td_bcnm.

type

The type of residuals to be returned. See residuals.nls.

...

Additional arguments currently not used.

Value

A vector of residuals.

Binary choice data for a single participant

Description

70 binary choices made by a single participant. Along with the columns required by td_bcnm, the reaction time (rt) is recorded.

Author(s)

Isaac Kinley isaac.kinley@gmail.com

References

doi:10.31234/osf.io/qjcwn

Binary choice data for a study

Description

Data from 421 participants, who each made 70 binary choices. Along with the columns required by td_bcnm, the reaction time (rt) in seconds is recorded. Participants are identified by the alphnumeric code in the id column.

Author(s)

Isaac Kinley isaac.kinley@gmail.com

References

doi:10.31234/osf.io/qjcwn

Temporal discounting binary choice linear model

Description

Compute a binary choice linear model for a single subject. In these models, we can recover the parameters of a discount function from the weights of a standard logistic regression. \beta_1

Usage

td_bclm(
  data,
  model = c("all", "hyperbolic.1", "hyperbolic.2", "exponential.1", "exponential.2",
    "scaled-exponential", "nonlinear-time-hyperbolic", "power",
    "nonlinear-time-exponential"),
  ...
)

Arguments

data

A data frame with columns val_imm and val_del for the values of the immediate and delayed rewards, del for the delay, and imm_chosen (Boolean) for whether the immediate reward was chosen. Other columns can also be present but will be ignored.

model

A string specifying which model to use. Below is a list of these models' linear predictors and the means by which we can recover discount function parameters.
'hyperbolic.1': \beta_1(1 - v_D/v_I) + \beta_2 t; k = \beta_2/\beta_1
'hyperbolic.2': \beta_1(\sigma^{-1}[v_I/v_D] + \log t) + \beta_2; k = \exp[\beta_2/\beta_1]
'exponential.1': \beta_1 \log (v_I/v_D) + \beta_2 t; k = \beta_2/\beta_1
'exponential.2': \beta_1(G^{-1}[v_I/v_D] + \log t) + \beta_2; k = \exp[\beta_2/\beta_1]
'scaled-exponential': \beta_1 \log (v_I/v_D) + \beta_2 t + \beta_3; k = \beta_2/\beta_1, w = \exp[-\beta_3/\beta_1] 'nonlinear-time-hyperbolic': \beta_1(\sigma^{-1}[v_I/v_D]) + \beta_2\log t + \beta_3; k = \exp[\beta_3/\beta_1], s = \beta_2/\beta_1
'nonlinear-time-hyperbolic': \beta_1(G^{-1}[v_I/v_D]) + \beta_2\log t + \beta_3; k = \exp[\beta_3/\beta_1], s = \beta_2/\beta_1
where \sigma^{-1}[\cdot] is the quantile function of the standard logistic distribution G^{-1}[\cdot] is the quantile function of the standard Gumbel distribution.

...

Additional arguments passed to glm.

Value

An object of class td_bclm, nearly identical to a glm but with an additional config component.

Examples


data("td_bc_single_ptpt")
mod <- td_bclm(td_bc_single_ptpt, model = 'hyperbolic.1')
print(coef(mod))

Temporal discounting binary choice nonlinear model

Description

Compute a binary choice model for a single subject

Usage

td_bcnm(
  data,
  discount_function = "franck-2015",
  choice_rule = c("logistic", "probit", "power"),
  fixed_ends = FALSE,
  fit_err_rate = FALSE,
  gamma_par_starts = c(0.01, 1, 100),
  eps_par_starts = c(0.01, 0.25),
  silent = TRUE,
  optim_args = list(),
  ...
)

Arguments

data

discount_function

A string specifying the name of the discount functions to use, or an object of class td_fn (used for creating custom discount functions), or a list of objects of class td_fn. Default is 'franck-2015', which is the set of widely used discount functions from Franck et al., 2015: https://doi.org/10.1002/jeab.128.

choice_rule

A string specifying whether the 'logistic' (default), 'probit', or 'power' choice rule should be used.

fixed_ends

A Boolean (false by default) specifying whether the model should satisfy the desiderata that subjects should always prefer something over nothing (i.e., nonzero delayed reward over nothing) and the same reward sooner rather than later. See here: https://doi.org/10.1016/j.jmp.2025.102902

fit_err_rate

A Boolean (false by default) specifying whether the model should include an error rate (parameterized by "eps"). See Eq. 5 here: https://doi.org/10.3758/s13428-015-0672-2.

gamma_par_starts

A vector of starting values to try for the "gamma" parameter (which controls the steepness of the choice rule) during optimization.

eps_par_starts

A vector of starting values to try for the "eps" parameter (which controls the error rate) during optimization. Ignored if 'fit_err_rate = FALSE'.

silent

Boolean (true by default). The call to optim() occurs within a try() wrapper. The value of silent is passed along to try().

optim_args

Additional arguments to pass to optim(). Default is list(silent = TRUE).

...

Additional arguments to provide finer-grained control over the choice rule. Note that using a custom choice rule causes the choice_rule and fixed_ends arguments to be ignored.

Value

An object of class td_bcnm with components data (containing the data used for fitting), config (containing the internal configuration of the model, including the discount_function), and optim (the output of optim()).

Examples


data("td_bc_single_ptpt")
mod <- td_bcnm(td_bc_single_ptpt, discount_function = "hyperbolic", fixed_ends = TRUE)
# Custom discount function
custom_discount_function <- td_fn(
  name = 'custom',
  fn = function(data, p) (1 - p['b'])*exp(-p['k']*data$del) + p['b'],
  par_starts = list(k = c(0.001, 0.1), b = c(0.001, 0.1)),
  par_lims = list(k = c(0, Inf), b = c(0, 1)),
  ED50 = function(...) 'non-analytic'
)
mod <- td_bcnm(td_bc_single_ptpt, discount_function = custom_discount_function, fit_err_rate = TRUE)

Temporal discounting drift diffusion model

Description

Fit a drift diffusion model for a single subject using maximum likelihood estimation.

Usage

td_ddm(
  data,
  discount_function,
  gamma_par_starts = c(0.01, 0.1, 1),
  beta_par_starts = c(0.25, 0.5, 0.75),
  alpha_par_starts = c(0.5, 1, 10),
  tau_par_starts = c(0.2, 0.8),
  drift_transform = c("none", "logis"),
  bias_adjust = FALSE,
  silent = TRUE,
  optim_args = list()
)

Arguments

data

A data frame with columns val_imm and val_del for the values of the immediate and delayed rewards, del for the delays, imm_chosen (Boolean) for whether the immediate rewards were chosen, and rt for the reaction times (in seconds). Other columns can also be present but will be ignored.

discount_function

A string specifying the name of the discount functions to use, or an object of class td_fn (used for creating custom discount functions), or a list of objects of class td_fn.

gamma_par_starts

A vector of starting values to try for the "gamma" parameter (drift rate multiplier or sharpness parameter) during optimization.

beta_par_starts

A vector of starting values to try for the "beta" parameter (bias) during optimization.

alpha_par_starts

A vector of starting values to try for the "alpha" parameter (boundary separation) during optimization.

tau_par_starts

A vector of starting values to try for the "tau" parameter (non-decision time) during optimization.

drift_transform

A transform to apply to drift rates. Either "none" (no transform), "logis" (sigmoidal transform described by Peters & D'Esposito, 2020, doi:10.1371/journal.pcbi.1007615, and Fontanesi et al., 2019, doi:10.3758/s13423-018-1554-2).

bias_adjust

Experimental feature. See not below.

silent

Boolean (true by default). The call to optim() occurs within a try() wrapper. The value of silent is passed along to try().

optim_args

Additional arguments to pass to optim(). Default is list(silent = TRUE).

Value

Note

Drift rates are computed based on the difference in subjective values between the immediate and delayed rewards. In theory, when they are equally valued, they should have equal probability of being chosen. However, this is only true when the bias parameter of the drift diffusion model (beta) is 0.5 (i.e., no bias). To make sure the immediate and delayed reward have equal probability of being chosen when they are equally valued, we can set bias_adjust = TRUE to add a bias correction factor to the drift rate. However, this feature is experimental and its effects on model fit etc. have not been tested.

Examples


data("td_bc_single_ptpt")
ddm <- td_ddm(td_bc_single_ptpt, discount_function = 'exponential',
              gamma_par_starts = 0.01,
              beta_par_starts = 0.5,
              alpha_par_starts = 3.5,
              tau_par_starts = 0.9)

Predefined or custom discount function

Description

Get a predefined discount function or create a custom discount function.

Usage

td_fn(
  predefined = c("hyperbolic", "nonlinear-time-hyperbolic", "exponential",
    "nonlinear-time-exponential", "absolute-stationarity", "relative-stationarity",
    "power", "nonlinear-time-power", "arithmetic", "nonlinear-time-arithmetic",
    "inverse-q-exponential", "scaled-exponential", "scaled-hyperbolic", "fixed-cost",
    "dual-systems-exponential", "additive-utility", "model-free", "constant"),
  name = "unnamed",
  fn = NULL,
  par_starts = NULL,
  par_lims = NULL,
  init = NULL,
  ED50 = NULL,
  par_chk = NULL
)

Arguments

predefined

A string specifying one of the pre-defined discount functions.

name

Name of custom discount function.

fn

Function that takes a data.frame called data (expected to contain the column del for delays) and a vector of named parameters called p, and returns a vector of values between 0 and 1 representing the indifference points computed at the given delay.

par_starts

A named list of vectors, each specifying possible starting values for a parameter to try when running optimization.

par_lims

A named list of vectors, each specifying the bounds to impose of a parameters. Any parameter for which bounds are unspecified are assumed to be unbounded.

init

A function to initialize the td_fn object. It should take 2 arguments: "self" (the td_fn object being initialized) and "data" (the data used for initialization).

ED50

A function which, given a named vector of parameters p and optionally a value of del_val, computes the ED50. If there is no closed-form solution, this should return the string "non-analytic". If the ED50 is not well-defined, this should return the string "none". As a shortcut for these latter 2 cases, the strings "non-analytic" and "none" can be directly supplied as arguments.

par_chk

Optionally, this is a function that checks the parameters to ensure they meet some criteria. E.g., for the dual-systems-exponential discount function, we require k1 < k2.

Value

An object of class td_fn.

Examples


data("td_bc_single_ptpt")
# Custom discount function
custom_discount_function <- td_fn(
  name = 'custom',
  fn = function(data, p) (1 - p['b'])*exp(-p['k']*data$del) + p['b'],
  par_starts = list(k = c(0.001, 0.1), b = c(0.001, 0.1)),
  par_lims = list(k = c(0, Inf), b = c(0, 1)),
  ED50 = 'non-analytic'
)
mod <- td_bcnm(td_bc_single_ptpt, discount_function = custom_discount_function, fit_err_rate = TRUE)

Simulated indifference point data for a single participant

Description

A dataframe containing simulated indifference points from a single participant exhibiting approximately hyperbolic discounting.

Author(s)

Isaac Kinley isaac.kinley@gmail.com

Temporal discounting indifference point model

Description

Compute a model of a single subject's indifference points.

Usage

td_ipm(
  data,
  discount_function = "franck-2015",
  optim_args = list(),
  silent = TRUE
)

Arguments

data

A data frame with columns indiff for the pre-computed indifference points and del for the delay.

discount_function

A vector of strings specifying the name of the discount functions to use, or an object of class td_fn (used for creating custom discount functions), or a list of objects of class td_fn. Default is 'franck-2015', which is the set of widely used discount functions from Franck et al., 2015: https://doi.org/10.1002/jeab.128.

optim_args

A list of additional args to pass to optim.

silent

A Boolean specifying whether the call to optim (which occurs in a try block) should be silent on error.

Value

An object of class td_ipm with components data (containing the data used for fitting), config (containing the internal configuration of the model, including the discount_function), and optim (the output of optim()).

Examples


# Basic usage
data("td_ip_simulated_ptpt")
mod <- td_ipm(td_ip_simulated_ptpt, discount_function = "hyperbolic")
# Custom discount function
custom_discount_function <- td_fn(
  name = 'custom',
  fn = function(data, p) (1 - p['b'])*exp(-p['k']*data$del) + p['b'],
  par_starts = list(k = c(0.001, 0.1), b = c(0.001, 0.1)),
  par_lims = list(k = c(0, Inf), b = c(0, 1)),
  ED50 = function(p) 'non-analytic'
)
mod <- td_ipm(td_ip_simulated_ptpt, discount_function = custom_discount_function)

Wileyto score a questionnaire

Description

Score a set of responses according to the method of Wileyto et al. (2004, doi:10.3758/BF03195548). This function is a thin wrapper to td_bclm.

Usage

wileyto_score(data)

Arguments

data

Responses to score.

Value

An object of class td_bclm.

Examples


data("td_bc_single_ptpt")
mod <- wileyto_score(td_bc_single_ptpt)

tempodisco: Temporal Discounting Models

Description

Author(s)

See Also

Area under the curve (AUC)

Description

Usage

Arguments

Value

Note

Examples

Median effective delay

Description

Usage

Arguments

Value

Examples

Indifference points from adjusting amount procedure

Description

Usage

Arguments

Value

Examples

Simulated adjusting amount procedure

Description

Author(s)

Test for failed attention checks

Description

Usage

Arguments

Value

Examples

Extract model coefficients

Description

Usage

Arguments

Value

Extract model coefficients

Description

Usage

Arguments

Value

See Also

Extract model coefficients

Description

Usage

Arguments

Value

See Also

Extract model coefficients

Description

Usage

Arguments

Value

See Also

Model deviance

Description

Usage

Arguments

Value

See Also

Model deviance

Description

Usage

Arguments

Value

See Also

Get discount function from model

Description

Usage

Arguments

Value

Examples

Get fitted values

Description

Usage

Arguments

Value

See Also

Get fitted values