PsychPlot function

Plot Psychometric Function from GLM

Plot a psychometric function given an object of class glm or brglm. The plot can be drawn on a new or existing ggplot object.

PsychPlot(
  model.obj,
  addTo = NULL,
  showData = TRUE,
  ps.type = "solid",
  ps.size = 1,
  ps.lab = ""
)

Arguments

• model.obj: the fitted psychometric function. An object of class glm or brglm.
• 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.
• showData: logical, defines if proportion of binomial responses for each stimulus level are presented. Default is TRUE.
• ps.type, ps.size: type and size of the plotted line (see "ggplot2-spec").
• ps.lab: label assigned to the psychometric curve. The label is coded by the color aesthetic.

Returns

PsychPlot returns a ggplot object.

Examples

data.S1 <- subset(simul_data, Subject == "S1")
psych.S1 <- PsychFunction(ps.formula = cbind(Longer, Total - Longer) ~ X, 
ps.link = "probit", ps.data = data.S1)
plotP1 <- PsychPlot(psych.S1$model, showData = TRUE, ps.lab = "S1") 

data.S2 <- subset(simul_data, Subject == "S2")
glm.S2 <- glm(formula = cbind(Longer, Total - Longer) ~ X, 
           family = binomial(link = "probit"), data = data.S2)
plotP2 <- PsychPlot(glm.S2, addTo = plotP1, ps.lab = "S2")

References

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.

See Also

glm for for Generalized Linear Models. PsychFunction for estimation of PSE and JND. MixPlot for plotting individual responses from a GLMM.