Simulate psychophysical data
The function simulates data from a typical psychophysics experiment using a 2-alternative forced choice task and the method of constant stimuli. For each simulated participant, the function returns the following information: individual slope and intercept coefficients, based on the fixed and random effects parameters provided as input; summary of the simulated binomial response across a range of intensity levels within a specified stimulus range; individual lapse and guess rates, if applicable.
PsySimulate( fixeff = c(-7, 0.0875), raneff = c(2.4, -0.002, 2e-06), nsubjects = 8, ntrials = 40, nintervals = 9, xint = c(40, 120), constant = T, lapse = FALSE, guess = FALSE, lapse_range = c(0, 0.05), guess_range = c(0, 0.05) )
fixeff: Numeric array of fixed effects. The first item is the intercept, the second element is the slope.raneff: Numeric array of random effects. The first element is the intercept, the second is the covariance, the third is the slope variance.nsubjects: Integer. Number of subjects to simulate. Default is 8.ntrials: Integer. Number of trials for each stimulus level. Default is 40.nintervals: Integer. Number of stimulus levels. Default is 9.xint: Numeric array specifying the range of stimulus intensity. Default is c(40,120)constant: Logical. If TRUE (defualt), stimulus levels are evenly spaced across xint. If FALSE, stimulus levels are randomly generated within the interval.lapse: Logical or numeric. If FALSE (default), no lapse rate is applied. If TRUE, a random lapse rate is drawn from lapse_range. If a numeric value is provided, all subjects will have the same lapse rate.guess: Logical or numeric. If FALSE (default), no guessing rate is applied. If TRUE, a random guessing rate is drawn from guess_range. If a numeric value is provided, all subjects will have the same guess rate.lapse_range: Numeric array defining the minimum and maximum lapse rates when lapse = TRUE. Default is c(0, 0.05).guess_range: Numeric array defining the minimum and maximum guessing rates when guess = TRUE. Default is c(0.05, 0.10).A data frame containing simulated psychophysical data with the following columns:
Subject - Subject identifier.X - Stimulus intensity levels.Intercept - Individual intercept values.Slope - Individual slope values.Gamma (optional) - Guess rate, included if guess is not FALSE.Lambda (optional) - Lapse rate, included if lapse is not FALSE.Longer - Number of "Longer" responses at each stimulus level.Total - Total number of trials per stimulus level.datafr.S1 <- PsySimulate(fixeff = c(0, 1), xint = c(-5,5), nsubject = 1, ntrials = 60, nintervals = 10, constant = FALSE) simul_data <- PsySimulate(ntrials = 160, nsubjects = 10, guess = TRUE, lapse = TRUE)
PsychShape for plotting a psychometric function given PSE and JND. simul_data for a dataset simulated with the function.