scalp.infl: inspect the influence of a subject on an average (scalp...
In erpR: Event-related potentials (ERP) analysis, graphics and utility functions

Description Usage Arguments Details Value Author(s) See Also Examples

The function returns a diagnostic plot to investigate the influence of a given ERP data frame on the grandaverage of a series of ERP data frames. A GUI is provided to explore the effect of removing a data frame (that is expected to be associated with a subject) from the grandaverage. Two plots are superposed: the original grandaverage, and the average removing the subject selected via the GUI. The plot shows an array of electrodes with a topography reflecting their positions on the scalp.

scalp.infl(base, numbers, smo = NULL, layout = 1, outnumber=1,
ylims = 12,  yrev = FALSE, startmsec = -200, endmsec = 1200, 
lwd = c(1, 2), lty = 1, col = "black", out.col = "red", 
erplist = NULL, t.axis=seq(-100,endmsec,200), scalp.array=NULL)

`base`	a string indicating the beginning of the name of the `data.frame` containing the ERP data.
`numbers`	the numbers of the subjects to be averaged.
`smo`	the smoothing parameter to apply (see `smooth.spline`). Default is `NULL` and no smoothing is applied.
`layout`	A number indicating the layout of electrodes to be plotted. Currently only few default layouts are supported (a number from 1 to 5). Alternatively, a character vector specifying the layout may be supplied (see `Details`).
`outnumber`	The number of the subject that will be initially removed from the averaged (this value could be changed also via the GUI).
`ylims`	a number indicating the upper and lower limits of the y axis. If "auto", the function calculates the y limits automatically.
`yrev`	logical. If `TRUE`, the y-axis is plotted with the negative values upward.
`startmsec`	the start time (in ms) of the ERP vector
`endmsec`	the end time (in ms) of the ERP vector
`lwd`	line width of the waveforms.
`lty`	line type of the waveforms.
`col`	the color of the grand average including all subjects.
`out.col`	the color of the grand average in which the selected subject is removed
`erplist`	a list containing ERP data frames.
`t.axis`	the position of the ticks on an additional axis indicating the time. This axis is plotted in the bottom-left corner of the plot array.
`scalp.array`	This argument is vector of two values indicating the number of panels of the plot, as number of rows and number of columns respectively. If a default layout is specified, the number of panels is automatically computed. See also `Details`.

The layout parameter can be a number (from 1 to 5), that specifies some default electrode arrangements (currently only a few default arrangements are supported). Otherwise, the argument may be a character vector indicating the names of the electrodes to be plotted. The plot is divided in a number of panels as specified in scalp.array. The names specified will be plotted from top to bottom and from left to right. If "blank" is specified an empty panel will be plotted. If "xaxis" is specified a x axis indicating time will be plotted. If "yaxis" is specified a y axis indicating voltage will be plotted.

The function returns a plot of a scalp array showing the influence of a subject on the grandaverage.

Giorgio Arcara

erp.infl, scalp

data(ERPsets)

# Notice that Subject 1 is clearly particularly influential 
# for the average on OZ.
scalp.infl(base="Exp1_word_subj", numbers=1:20, layout=1, 
startmsec=-200, endmsec=1500, erplist=ERPsets)