Installation¶

1. Download and place the pylinkwrapper folder somewhere you can easily reach in the file system.
2. Add the folder to Psychopy’s python path as detailed here: http://www.psychopy.org/recipes/addCustomModules.html
3. Update pylink to the latest version provided by the SR Research development kit. It should be installed on the display computer.

That’s it! Here’s a quick demo of getting connected to the Eyelink:

import pylinkwrapper

win = visual.window(monitor='nickMon', fullScr=True, allowGUI=False, color=-1)
tracker = pylinkwrapper.connect(win, '1_nd')

Check out the documentation for the Connector Class class to see what functions are available.

Connector Class¶

This class provides methods for interacting with the Eyelink from psychopy.

class connector.Connect(window, edfname)¶

Provides functions for interacting with the EyeLink via Pylink.

Parameters:	window – Psychopy window object. edfname (str) – Desired name of the EDF file.

calibrate(cnum=13, paval=1000)¶

Calibrates eye-tracker using psychopy stimuli.

Parameters:	cnum (int) – Number of points to use for calibration. Options are 3, 5, 9, 13. paval (int) – Pacing of calibration, i.e. how long you have to fixate each target in milliseconds.

convert_coords(x, y, to='eyelink')¶

Converts from degrees visual angle units to EyeLink Pixel units.

Parameters:	x (float or int) – X coordinate in visual angle. y (float or int) – Y coordinate in viusal angle. to – Direction of conversion. Options: ‘eyelink’ or ‘psychopy’.
Returns:	Two values in order x, y

draw_ia(x, y, size, index, color, name)¶

Draws square interest area in EDF and a corresponding filled box on eye-tracker display. Must be called after set_trialid() for interest areas to appear in the EDF.

Parameters:	x (float or int) – X coordinate in degrees visual angle for center of check area. y (float or int) – Y coordinate in degrees visual angle for center of check area. size (float or int) – length of one edge of square in degrees visual angle. index (int) – number to assign interest area in EDF color (int) – color of box drawn on eye-tracker display (0 - 15) name (str) – Name of interest area in EDF

draw_text(msg)¶

Draws text on eye-tracker screen.

Parameters:	msg (str) – Text to draw.

end_experiment(spath)¶

Closes and transfers the EDF file.

Parameters:	spath (str) – Absolute file path of where to save the EDF file.

fix_check(size, ftime, button)¶

Checks that fixation is maintained for certain time.

Parameters:	size (float or int) – Length of one side of box in degrees visual angle. ftime (float) – Length of time to check for fixation in seconds. button (char) – Key to press to recalibrate eye-tracker.

get_gaze()¶

Gets current gaze position of eye. Must be called between record_on() and record_off(). Sendlink must be set to True as well.

Returns:	list of coordinates in the form of [x, y].

record_off()¶

Stops recording.

record_on(sendlink=False)¶

Starts recording. Waits 50ms to allow eyelink to prepare.

Parameters:	sendlink (bool) – Toggle for sending eye data over the link to the display computer during recording.

sac_detect(x, y, radius)¶

Checks if current gaze position is outside a circular interest area.

Parameters:	x (float or int) – X coordinate in degrees visual angle for center of circle IA. y (float or int) – Y coordinate in degrees visual angle for center of circle IA. radius (float or int) – Radius of detection circle in degrees visual angle.
Returns:	List of whether saccade was detected and the gaze coordinates

at time of detection. In the form of [bool, [x, y]]. :rtype: bool, list

send_command(cmd)¶

Sends a command to the Eyelink.

Parameters:	cmd (str) – Command to send.

send_message(txt)¶

Sends a message to the tracker that is recorded in the EDF.

Parameters:	txt (str) – Message to send.

send_var(name, value)¶

Sends a trial variable to the EDF file.

Parameters:	name (str) – Name of variable. value (float, str, or int) – Value of variable.

set_status(message)¶

Sets status message to appear while recording.

Parameters:	message (str) – Text object to send, must be < 80 char

set_trialid(idval=1)¶

Sends message that indicates start of trial in EDF.

Parameters:	idval – Values to set TRIALID.

set_trialresult(rval=0, scrcol=0)¶

Sends trial result to indiciate trial end in EDF and clears screen on EyeLink Display.

Parameters:	rval (float, str, or int) – Value to set for TRIAL_RESULT. scrcol (int) – Color to clear screen to. Defaults to black.

Sample Experiment¶

This is a very simple experiment that demonstrates use of pylinkwrapper. It can be found in the sample folder.

"""
Pylink Wrapper test experiment
N. DiQuattro - January 2015

This is a simple experiment where a circle appears randomly on the screen. It's
purpose is to provide examples of how to use the pylink wrapper with a psychopy
experiment.

There's help documentaiton available for each of the functions that show the
available parameters.
"""

# Import modules
from psychopy import visual
from psychopy import core, event
import numpy as np

import pylinkwrapper  # Here's the special one

# Window set-up
win = visual.Window(monitor='nickMon', units='deg', fullscr=True,
                    allowGUI=False, color=0)

# Initiate eye-tracker link and open EDF
tracker = pylinkwrapper.Connect(win, '1_test')

# Calibrate eye-tracker
tracker.calibrate()

# Stimulus
fix = visual.Circle(win, radius=1, pos=(0, 0), fillColor=[1, 0, 0],
                    lineColor=[1, 0, 0])

cfix = visual.Circle(win, radius=.15, fillColor=-1, lineColor=-1)

# Display stimulus 5 times
for t in range(5):
    # Find random coordinates and set them
    fx = np.random.randint(-10, 10)
    fy = np.random.randint(-10, 10)
    fix.setPos((fx, fy))

    # Eye tracker trial set-up
    stxt = 'Trial %d' % t
    tracker.set_status(stxt)  # Define status message that appears on eye-link
    #  display

    tracker.set_trialid()  # Sends trial start message for EDF
    tracker.send_message('Circle Trial')

    # Draw IA
    tracker.draw_ia(fx, fy, 1, 1, 5, 'circle')  # Draw interest area and box

    # Start recording
    tracker.record_on()

    # Draw and display circle
    cfix.draw()
    fix.draw()
    win.flip()

    # Wait for response 
    keyp = event.waitKeys()

    # Stop Recording
    tracker.record_off()

    # Send response key to EDF file
    tracker.send_var('response', keyp[0][0])

    # End trial for EDF
    tracker.set_trialresult()

    # ISI with fixation check
    cfix.draw()
    win.flip()
    tracker.fixcheck(2, 1, 'z')

# Retrieve EDF
tracker.end_experiment('C:\\edfs\\')  # Closes and retrieves EDF file to
# specified path