Go to the waiting area and hold up the MARMB2 placard.
Ask who is there for this study.
Ask to see their registration page to confirm their appointment.
Direct them to EEG-D — this is where Qualtrics, Chrome, and the Discord call are set up for this study.
⚠Do NOT ask for student ID. Attendance is tracked via the did variable in Qualtrics.
02
Consent Signature — EEG-D Consent
Before opening Chrome: Start a Discord call between EEG-D and the outside computer so you can hear the participant when they call for you.
Open Google Chrome and select Mani's EEG study. A spreadsheet will automatically open.
Locate the participant's appointment, click their specific link, and tick the attendance checkbox.
Give the participant the password to access the consent form, then step out and close the door.
⚠The password prevents participants from completing the survey remotely before attending in person.
03
Sizing & Consent Decision Consent
The participant may ask questions about the study. Answer them as needed.
If they consent: Qualtrics prompts them to call you over for head measurement.
If they do not consent: Skip head measurement — they complete the alternative task only.
Head Measurement
Have the participant hold the tip of the measuring tape on the bridge of their nose between their eyebrows.
Wrap the tape around their head, following the natural indentation at the back of the skull (just below the inion). Note the measurement in centimeters.
Select the net size whose range the measurement falls toward the upper limit of — a snugger fit produces better signal.
⏱After notifying you of their decision, participants cannot advance for 3 minutes (enforced by Qualtrics).
04
Demographics, Net Soaking & VREF Setup
While the participant completes demographics in Qualtrics, soak the net and mark VREF.
Net Soaking
Fill the electrolyte bucket to the 2L line with warm water.
Submerge the net and start the timer for 10 minutes.
Finding & Marking VREF
Front to back: Measure from the bridge of the nose to the inion. Mark the halfway point with a red crayon.
Side to side: Have the participant open and close their mouth to locate the jaw hinge indentation just in front of each ear. Stretch the tape from one side to the other over the crown of the head. Mark the midpoint.
VREF is where these two lines intersect. Mark it clearly — you need to find it quickly during cap fitting.
Prepare the Participant
Wrap a towel around their shoulders.
Ask them to remove any jewelry that might catch in the net (e.g., bulky earrings).
If wearing makeup, provide a makeup wipe to clear the forehead and cheek area.
Hand them a towel — water droplets will fall on their face during cap application.
When Qualtrics finishes demographics, the participant will be prompted to call you for cap fitting.
EEG Preparation Begins
05
Critical Stage — Record IDs Task
Qualtrics now displays two values essential for the rest of the session. Record both before proceeding:
Participant Numeric ID — assigned by Qualtrics. Used in Net Station and E-Prime.
Code — determines which E-Prime study file to run.
⏱No Next button for 20 minutes — this is intentional. Use this window to complete cap fitting and photogrammetry.
⚠The RA enters the Participant ID into Net Station — not the participant.
06
EEG Cap Application EEG
Bring the participant to the sink area. Lift the net by placing both hands underneath the chin straps, fingers spread wide to stretch it open. Do not discard the soaking solution — you will need it for impedance.
Applying the Cap
Apply back to front — posterior electrodes contact the scalp first, then move forward to place frontal and cheek electrodes.
Aim to place VREF directly over the crayon mark. The front-most electrode should sit between the eyebrows; the row above rests on the eyebrows.
The ear holes should fit around the participant's ears, with the unnumbered dummy electrodes positioned just in front of each ear.
Adjusting & Tightening
To adjust, do NOT pull individual electrodes — this can break them. Make a claw shape with your fingers and shift a cluster of electrodes together in a gentle scrunching motion.
Tighten the three chin straps in small increments: blue under the chin, white around the neck, red for the cheeks.
Check in with the participant — straps should be snug but not uncomfortable.
Symmetry Check
Place your fingers on the dummy electrodes in front of both ears.
From the front: both fingers should be at equal height.
From above: both fingers should be aligned with each other.
Ensure no electrodes are flipped upside down before leaving the sink area.
07
Photogrammetry EEG
Adjust the dome per the manual specifications, then complete the following in Net Station:
Click Photogrammetry under Tools in the Net Station home screen.
Click New in the Photogrammetry window.
Navigate to Desktop → Mani → Photogrammetry and name the file: Mani EEG [Participant ID]
Set Net Size to HydroCel GSN 256 1.0.
Click Assign Subject and type: Mani EEG [Participant ID]
Click Capture Images.
Net Station home → Photogrammetry (under Tools)Photogrammetry window — Net Size and Assign Subject
ℹOnce photogrammetry is complete, move the participant into EEG-B. Hook up the EEG net to the power supply. One RA should remain at the outside Mac for the rest of the session.
In Identify Subject, type: Mani EEG [Participant ID]
Under Session Information, enter the Experiment Code as a number (from Qualtrics).
Enter the Participant ID (numbers only).
Click Begin Session.
Net Station — Enter Session Information dialog
08b
Impedance Check EEG
Bring the soaking solution bucket, a pipette, and a warm water spray bottle into EEG-B before beginning.
Running Impedance
In the Net AMPS 300 Controls window, click Measure Net Impedance.
On the VIDMUX switch box, press MAC (button 1) so the chamber monitor shows the Mac screen.
Drag the impedance window to the right until all sensors are visible on the chamber monitor.
Leave a small corner on screen so you can grab it back.
Enter the chamber and fix red sensors:
Large clusters of red: spray the area with the warm water spray bottle.
Isolated red sensors: flip the electrode sideways, apply a few drops of the original soaking solution via pipette, then flip it back.
Once all sensors are green, drag the impedance window back and close it. No need to save.
Demonstrate Movement Artifacts
After closing impedance, drag the waveform display window to the right so it appears on the chamber screen.
Ask the participant to clench their jaw, blink, and move their eyes side to side — let them see how movement corrupts the signal in real time.
Emphasize the importance of staying as still as possible during the task.
Drag the waveform display back to the main screen before proceeding.
Net Amps 300 Controls — Measure Net ImpedanceVIDMUX switch — press MAC (1) to show Mac on chamber screen
⚠Impedance degrades as water evaporates. Work efficiently.
Task Execution — EEG-B
09
Running the Experiment Task
Launch E-Prime
Find the E-Prime shortcut corresponding to the Code from Qualtrics.
Enter the Participant ID (numbers only). Set Session to 1. Click OK.
On the VIDMUX switch box, press PC (button 2) so the chamber monitor now shows the E-Prime / Windows XP screen.
Baseline Recording
Enter EEG-B and read the Baseline script aloud to the participant.
Exit the chamber and close the door.
From outside, press Shift + A to advance the participant to the fixation cross.
Start a 3-minute timer. After 3 minutes, press Shift + A to end the baseline.
Article Task
Re-enter EEG-B and read the Article task script aloud to the participant.
Tell them you will step outside again, and that they should press Shift + A themselves to advance through the instructions and article.
Exit and close the door. Monitor from outside.
When the thank-you screen appears, enter EEG-B.
⚠Do NOT click Record, Pause, or any other Net Station controls. Recording starts and stops automatically.
Post-Task Measures — Back to EEG-D
10
Post-Task Questionnaires & Debrief Wrap-Up
When the thank-you screen appears, enter EEG-B and direct the participant to EEG-D. The EEG cap stays on.
On the Way to EEG-D
Ask the participant to grab their phone on the way.
Explain why: they will need it to scan a QR code for the debrief form. This form also serves as their proof of attendance if there are any credit tracking issues.
If they don't have their phone, a physical QR code copy is available — not a problem.
In EEG-D (∼5 minutes)
Give the participant the second password to access the post-task Qualtrics stage.
Close the door for privacy. The Discord call is active — you will hear when they are done.
The participant completes post-task questions, reads the debrief, and scans the QR code.
They will tell you via Discord when they are finished.
ℹThe debrief form and Qualtrics completion record are the participant's proof of attendance. Important if there are any scheduling or credit tracking disputes.
EEG Removal & Session End
11
Remove EEG Cap EEG
This is the final step. Bring the participant to the sink area. This is a natural time for them to ask any remaining questions about the study.
Removing the Cap
Loosen all three chin straps first.
Face the participant. Reach under the net with both hands spread wide, palms against their head, so that the facial and frontal electrodes are the first in contact with your hands.
Lift your hands up and back — frontal electrodes detach first, followed by central, then posterior electrodes.
If the participant has long hair and the net catches, partially remove it, then gently pull the cord in an up-down motion while holding their hair flat to prevent discomfort.
Net Rinsing
Follow the rinsing instructions in the binder posted in the sink area.
Hair & Session End
Inform the participant that washing their hair is not required — this specific net does not necessitate it.
If they would like to wash anyway, offer assistance or direct them to the private room.
Note that their 50-minute session has ended after the debrief. Any extra time is their own.
