What is P300?
The P300 (or P3) is an event-related potential (ERP) — an electrical response of the brain that occurs about 300 milliseconds after the presentation of a significant, novel, or expected stimulus. It reflects the brain's detection and processing of meaningful information.
Key Properties
- •Latency — ~300 ms after stimulus
- •Amplitude — stronger when stimulus is more salient or surprising
- •Location — maximal over parietal cortex
- •Function — attention allocation, context updating, decision-making
Why does P300 matter?
P300 matters because it offers a measurable window into attention and how the brain evaluates important or unexpected events. It is one of the most studied brain responses in cognitive neuroscience.
Researchers use it to study processing speed, attention, and memory. It also powers some brain-computer interfaces, such as "P300 spellers" that let people with severe paralysis choose letters by focusing attention on them.
How is P300 measured?
P300 is measured with EEG, using electrodes on the scalp while a person performs a simple task. The most common setup is the "oddball" paradigm, in which a person hears or sees a stream of frequent standard stimuli mixed with rare target stimuli they are asked to notice.
Because a single brain response is small compared with background activity, researchers average many trials together to reveal the P300 wave. They then look at its amplitude, which tends to relate to how much attention the event captures, and its latency, which reflects how quickly the brain evaluates it. Both vary with age, fatigue, and task difficulty, so results are usually compared against suitable control groups rather than one universal standard.
In ONDA Life
Part 7 names "P300 Amplitude Increase" as an aim of the practice. ONDA does not record EEG, so the app does not measure P300 and does not track it as progress; the phrase describes a goal of the program, not a result you can check in the app.