opiTemporalStimulus: Stimulus parameter list.
In OPI: Open Perimetry Interface

Description Details Author(s) References Examples

List containing stimulus parameters with an S3 class attribute of opiTemporalStimulus.

x coordinate of the center of stimulus in degrees relative to fixation
y coordinate of the center of stimulus in degrees relative to fixation
image an image to display in a machine specific format
lut if is.na(image) then this is a lookup table (vector) for stimulus level at each step of rate Hz in cd/m^2. If image is specified, then this is a list of images, in the same format as image, that is stepped through at rate Hz.
size diameter of target in degrees, or scaling factor for image if specified
color machine specific stimulus color settings (ignored if !is.na(image))
rate frequency with which lut is processed in Hz
duration total length of stimulus flash in milliseconds. There is no guarantee that duration %% length(lut)/rate == 0. That is, the onus is on the user to ensure the duration is a multiple of the period of the stimuli.
responseWindow maximum time (>= 0) in milliseconds to wait for a response from the onset of the stimulus presentation
... machine specific parameters

Octopus 900

x and y are in degrees, with precision to one decimal place recognised.

image is not possible on an Octopus 900.

lut is not possible on an Octopus 900. Stimulus is at 0 dB.

rate is in Hz, with precision to one decimal place recognised.

color is ignored. Use opiSetBackground() to alter stimulus color.

Kowa AP-7000

Not supported.

Kowa AP-7000

Not implemented.

Andrew Turpin <[email protected]>

Please cite: A. Turpin, P.H. Artes and A.M. McKendrick "The Open Perimetry Interface: An enabling tool for clinical visual psychophysics", Journal of Vision 12(11) 2012.

http://perimetry.org/OPI

    # A Size III flickering with a 10Hz square wave at
    # location (7,7) with luminance 10 dB (HFA) 
stim <- list(x=7, y=7, size=0.43, color="white", 
                rate=20,        # one lut step per 50 ms 
                lut=c(0,318),   # so one full lut per 100 ms == 10Hz 
                duration=400,   # and 4 cycles per stimulus
                responseWindow=1500) 
class(stim) <- "opiTemporalStimulus"