Run eye tracking calibration ‘xxxxxx’ on Kif

Verify screen refresh rate is at 60Hz and hit enter to continue. Calibration dots should appear in white on Kif (upper left) and subject monitors.

Thresholding

On Hypnotoad

• click the upper right box in the eye camera pane to enlarge it.
• In the face camera pane, click and drag between the subject’s eyes until their eyes are centered in the eye camera
• Uncheck the box in the eyecam pane
• Click on ‘track active’ box between eye and face cam panes. In the upper left pane, auto-thresholding should get relatively close
• Adjust the PR and CR sliders in small increments to achieve proper thresholding in eye cam
• Unclick the check box in the eye cam pane to show tracking graphs.

Calibration

On Hypnotoad

• Click ‘options’ between the tracking graphs until the calibration pane shows in the bottom left
• In the calibration pane, click on ‘POR Calib’ (all clicking in this pane is on the circular radio buttons, not the check boxes)

Tell the subject that you will Instruct the subject to look at each dot in turn and fixate on that dot as steadily as possible.

As the subject saccades to the new dot, they will often blink. Wait for the blink in case it happens and after the tracking graphs steady out

• Rclick in the display area with the dots in the calibration pane
  • This will move to the next dot which will be circled in red.

Calibration moves from center to the top left and clockwise, returning to center. Once the participant has returned to center

• Click ‘Reset’
• click ‘POR out’

Ask the subject to look at the corners of the screen in turn, you should see their point of regard in the calibration pane track their eyes to the corresponding corners. If it loses tracking near the corners, repeat the process to recalibrate.

On Kif, we will continue with the PTB script to calibrate a second time.

• Instruct the subject to fixate on the center dot. One dot at a time will turn green, they should fixate steadily on that dot until it turns white.
• Hit the spacebar to begin the process. After each dot returns to white, hit the space bar to move to the next dot.
  • It will cycle through each position a number of times.
• When finished, a grouping of green dots will appear around each point displaying the calculated fixations. If any are extremely far from a white dot or an entire group is shifted by more than a half inch or so, rerun calibration.
• Clicking spacebar again will display a red dot showing current fixation point, you can have the subject fixate on each point to verify adequate calibration
• If calibration crashes, either they are not fixating well enough, the Hypnotoad calibration is off, or the thresholding needs to be improved. Start from the beginning again with Hypnotoad.