languageR (version 1.0)

imaging: fMRI Filtered Signal and Priming Scores for Brain-Damaged Patients

Description

Filtered fMRI signal at the most significant voxel and average priming scores for brain-damaged patients, in a study addressing the extent to which phonological and semantic processes recruit the same brain areas.

Usage

data(imaging)

source

Tyler, L.K., Marslen-Wilson, W.D. and Stamatakis, E.A. (2005) Differentiating lexical form, meaning, and structure in the neural language system, PNAS, 102, 8375-8380.

Details

Location of data points reconstructed from the pixel map of Figure 2b of Tyler et al. 2005.

Examples

data(imaging)

imaging.lm = lm(FilteredSignal~BehavioralScore*Condition, data=imaging)
summary(imaging.lm)

plot(imaging$BehavioralScore, imaging$FilteredSignal, type = "n", 
  xlim = c(-30, 40), ylim = c(0, 80))
semantics = imaging[imaging$Condition == "semantics",]
irregulars = imaging[imaging$Condition == "irregulars",]
points(semantics$BehavioralScore, semantics$FilteredSignal, col = "black")
points(irregulars$BehavioralScore, irregulars$FilteredSignal, col = "darkgrey")
abline(lm(FilteredSignal ~ BehavioralScore, data = semantics), col = 'black')
abline(lm(FilteredSignal ~ BehavioralScore, data = irregulars), 
  col = 'darkgrey')

# model criticism

plot(imaging.lm)
outliers = c(1, 19) # given Cook's distance, or perhaps only
outliers = 1        # the outlier in the semantics subset
imaging.lm = lm(FilteredSignal ~ BehavioralScore * Condition, 
  data = imaging[-outliers, ])
summary(imaging.lm)