PsychShape: Plot Psychometric Functions given PSE and JND
In MixedPsy: Statistical Tools for the Analysis of Psychophysical Data

Description Usage Arguments Details Value References See Also Examples

View source: R/psych_utils.R

Plot a psychometric function with known PSE and JND on a new or existing ggplot object.

PsychShape(
  pse = 0,
  jnd = 1,
  p = 0.75,
  x.range = c(NA, NA),
  ps.link = c("probit"),
  ps.type = "solid",
  ps.size = 1,
  ps.color = "black",
  addTo = NULL
)

`pse, jnd`	point of subjective equivalende (PSE) and just noticeable difference (JND) of the desired psychometric function.
`p`	probability value relative to the JND upper limit. Default is 0.75 (value for 50% JND).
`x.range`	vector of length two specifying the range of the psychometric function.
`ps.link`	a link function for the binomial family of error distribution.
`ps.type, ps.size, ps.color`	type, size, and color of the plotted line (see `"ggplot2-spec"`).
`addTo`	specifies an existing `ggplot` object where the new line should be plotted. If no object is given, the function is drawn on a new plot.

PsychShape() can be used to visualize the predicted results of a psychophysical experiment or to plot a fitted psychometric function whose values of pse and jnd are known. Currently only working with probit and logit link function.

PsychShape returns a ggplot object.

Moscatelli, A., Mezzetti, M., & Lacquaniti, F. (2012). Modeling psychophysical data at the population-level: The generalized linear mixed model. Journal of Vision, 12(11):26, 1-17. doi:10.1167/12.11.26

Knoblauch, K., & Maloney, L. T. (2012). Modeling psychophysical data in R (Vol. 32). Springer Science & Business Media.

glm for for Generalized Linear Models. PsychFunction and PsychDelta for estimation of PSE and JND from response data. PsychPlot for plotting a a psychometric function from a GLM.

p <- PsychShape(pse = 0, jnd = 6, x.range = c(-40, 40), ps.color = "gray", ps.size = 3)
p1 <- PsychShape(pse = 6, jnd = 6, x.range = c(-40, 40), ps.col = "black", addTo = p)
p2 <- PsychShape(pse = 6, jnd = 6, x.range = c(-40, 40), ps.col = "red", ps.link = "logit", 
ps.type = "dashed", addTo = NULL)