EEG and ERP Essentials

$EEG$ (electroencephalogram) records electrical brain activity non-invasively from the scalp.
Uses a cap with multiple electrode wells; metal disk electrodes snap in and detect tiny voltage changes from cortical neurons.
Conductive gel bridges scalp and electrode to improve signal conduction.

Electrode → wire → amplifier (boosts signal) → computer for visualization/analysis.

Excellent temporal resolution (millisecond-level).
Poor spatial resolution: signals are attenuated and blurred by skull; cannot pinpoint exact neuronal source.

High-density caps increase sampling points but do not overcome skull barrier.
Raw signal is noisy (muscle activity, environmental interference, statistical noise) and messy to interpret directly.
Typical applications: sleep-stage identification via characteristic wave patterns.

$ERP$ = averaged EEG time-locked to a repeated event/stimulus.
Averaging across many trials cancels random noise, leaving a clearer waveform that reflects event-specific neural processing.
Components (peaks/troughs) represent changes from baseline; their amplitude/latency are compared across conditions (e.g., dog-lovers vs. non-lovers).
Provides precise timing of cognitive processes within ~0–800 ms after stimulus; still limited spatially by scalp recording.

EEG offers non-invasive, real-time monitoring of brain activity but with coarse localization.
ERP leverages EEG’s timing strength by isolating stimulus-locked signals through trial averaging.
Together, they enable cognitive psychologists to study human neural processing ethically and effectively, despite spatial limits.