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Dealing with the Unexpected - the P300 Signal
  • Human
  • Grade 9+

Dealing with the Unexpected: The P300 Signal

Record the P300 — a burst of brain activity that appears about 300 ms after you hear something unexpected — using only the Human SpikerBox, a BYB EEG headband, and the P300 sounds built into SpikeRecorder.

Devices and Accessories4Related Experiments3

About the Experiment

What Will You Learn?

What Will You Learn?

  • How the oddball paradigm evokes the P300 event‑related potential.
  • How to capture parietal EEG with the Human SpikerBox and SpikeRecorder.
  • How to average standard and oddball trials to reveal the P300 peak.
Background

Background

The P300 is a positive EEG wave peaking about 300 ms after an unexpected tone and is largest over Pz. A single-channel, low-cost setup can detect it after simple trial averaging (Smith et al. 2024, J Undergrad Neurosci Educ; full citation under Results).

Procedure

  1. Electrode & Device Setup:

    1. Place one headband pad at Pz (10–20 system) with conductive gel and clip one red lead to it.
    2. Clip the other red lead to a sticker on your left mastoid (the bone behind the ear) and the black lead to a sticker behind your right ear.
    3. Plug the orange cable into the Human SpikerBox and connect to your laptop or phone.
    4. Open SpikeRecorder, set the channel to EEG mode and enable the 50/60 Hz notch filter.
    Electrode & Device Setup:

  2. Run the Oddball Task:

    1. Wear headphones and start the P300 (oddball) sounds built into SpikeRecorder; there is no separate sound file to download. (In BYB’s study, 90% of tones were a 300 Hz standard and 10% a 500 Hz oddball, one tone every 2 s.)
    2. Press Record in SpikeRecorder. Relax, count oddballs silently, minimise blinking.
    Run the Oddball Task:

  3. Save & Analyze:

    1. Stop recording; save the EEG as a WAV file.
    2. Use SpikerTools, Backyard Brains’ open-source Python library (github.com/BackyardBrains/SpikerTools), to cut −100 ms → 800 ms around each marker, baseline‑correct, and plot the average response (ERP) for oddball vs. standard tones.
    3. Locate the largest positive peak between 250 ms and 600 ms — your P300.
Results & Analysis

Results & Analysis

In BYB’s published study, oddball averages showed a clear P300 in 64% of lab recordings (average peak latency 442 ms) and in about two-thirds of classroom sessions; the peak is small or absent in standard trials. A strong P300 shows that your brain noticed and paid attention to the unexpected tone; the same signal can also drive P300‑based interfaces.

Method adapted from Smith K, Pilger A, Amorim MLM, Mircic S, Reining Z, Ristow N, Miller D, Leonhardt A, Donovan JC, Meier M, Marzullo TC, Serbe-Kamp E, Steiner AP, Gage GJ. “Low-Cost Classroom and Laboratory Exercises for Investigating Both Wave and Event-Related Electroencephalogram Potentials.” J Undergrad Neurosci Educ 2024;22(3):A197–A206. doi:10.59390/YNPH4485. Free full text: https://pmc.ncbi.nlm.nih.gov/articles/PMC11441432/