PPHY

• Author: Guillaume T. Vallet, gtvallet@gmail.com, Université de Montréal, CRIUGM
• Version: 0.5
• Date: 2018/02/03
• Update:
  • 2014/11/04 -- Fix minor bug to display the horizontal line of the PSS
  • 2015/03/26 -- Handle multiple conditions
  • 2018/02/03 -- Fix bug when vars==NULL

Pphy is R package developed for a personal use to process psychophysic data. Pphy uses the modelfree package to fit the data locally per subject. The slope and the point of subjective equivalence are extracted per subjects and conditions. The package also provide a simple plot function based on the ggplot2 package to draw a graphic per subject and one graphic of the averaged data with standard error (optionally). The means per subjects and conditions are also returned.

The detailed description of the functions as well as examples are provided in the R documentation. Type ?*function_name* in your R console to access it.

Table of Contents

• Licence
• Dependencies
• Installation
• Functions

Licence

This package is released under the Creative Common Attribution-NonCommercial-ShareAlike 4.0 International license.

Dependencies

Pphy depends on the following pacakges :

• plyr,
• ggplot2,
• grid,
• gridExtra,
• modelfree,
• predata.

All these packages, except predata, can be install by typing install.packages('package_name') in your R console. The predata package should install from Github as the the pphy package (see below).

Installation

To install a R package from Github, you first need to install the devtools package. In R, type install.packages('devtools'). Then install pphy with the following command : install_github('cogitos/pphy'). You can also install predata by typing install_github('cogitos/predata'). And now enjoy the package!

Functions

fitPPCurve

This function is simple wrapper to the modelfree package to fit locally a set of psychophysic data and then extract the slope and the point subjective equivalence.

psychophy

This function will run the fitPPCurve function for each subject and condition of the experiment. The function will return the raw data, the means per subjects and conditions, the extracted indexes from the fitted values (e.g. slopes) and a list of two plots. The first plot is a matrix of plots, one per subject, with the raw data and the fitted data. The second plot is the averaged means across subjects with standard errors.

plotPPCurve

This function use the ggplot2 package to draw a psychometric curve into a nice and clean visual theme. The function automatically draw the point of objective equivalence and can add the standard errors as well.