Updating p300 an integrative theory of p3a and p3b
This shows two important findings: first that this late positivity occurred when the uncertainty about the type of click was resolved, and second that even an absence of a stimulus, when it was relevant to the task, would elicit the late positive complex.
These early studies encouraged the use of ERP methods to study cognition and provided a foundation for the extensive work on the P3b in the decades that followed.
However, using a 15-electrode setup with a linked-earlobe reference and an oddball task (described below), researchers have also found that the positivity increased moving from frontal to parietal sites, and that females have a greater increase than males.
Thus, the exact distribution may be dependent upon the task, as well as the gender and age of the subjects.
The P3b has been a prominent tool used to study cognitive processes for several decades.
More specifically, this ERP component has played a key role in cognitive psychology research on information processing.
They also found that the ERP responses to the numbers, but not to the light flashes, contained a large positivity that peaked around 300 ms after the stimulus appeared.
They also noted that the amplitude of this positivity was not affected by the intensity of the stimulus.
They found that when subjects were required to guess what the following stimulus would be, the amplitude of the "late positive complex" they presented two cue types.Amplitude has been defined as the difference between the mean pre-stimulus baseline voltage and the voltage of the largest (in this case, positive-going) peak of the ERP waveform in a specific time window.), but varies systematically as a function of a number of important factors (see Functional significance: Factors that influence amplitude).Latency has been defined as the time from the onset of the stimulus (or whatever the desired point of measurement might be) to the point of maximum amplitude.Generally speaking, improbable events will elicit a P3b, and the less probable the event, the larger the P3b.However, in order to elicit a P3b, the improbable event must be related to the task at hand in some way (for example, the improbable event could be an infrequent target letter in a stream of letters, to which a subject might respond with a button press).