ecc2 | R Documentation |
Letter detection and identification at 2 degrees eccentricity in the visual field. On each trial, one of four letters (b, d, p, q) were presented in one of four positions (superior, inferior, left, right) in the visual field. In a given session, the letter height was fixed. Six contrast levels were tested in each session. The data indicate the proportion of correctly identified positions, referred to here as detection, and the proportion of correctly identified letters, conditional on correct identification.
data(ecc2)
A data frame with 48 observations on the following 5 variables.
Contr
numeric. The contrast of the stimulus, defined as Weberian contrast.
task
a factor with levels DET
ID
indicating the two tasks, detection and identification.
Size
a numeric vector indicating the letter height
Correct
an integer vector indicating the number of correct responses (DET
or ID
).
Incorrect
an integer vector, indicating the number of incorrect responses.
Yssaad-Fesselier, R. and Knoblauch, K. (2006) Modeling psychometric functions in R. Behav Res Methods., 38(1), 28–41.
data(ecc2)
library(lattice)
xyplot(Correct/(Correct + Incorrect) ~ Contr | Size * task, ecc2,
type = "b", scale = list(x = list(log = TRUE),
y = list(limits = c(0, 1.05))),
xlab = "Contrast", ylab = "Proportion Correct Response",
panel = function(x, y, ...) {
panel.xyplot(x, y, ...)
panel.abline(h = 0.25, lty = 2)
})
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