User Reference:P3TemporalFilter

Function

The P3TemporalFilter performs buffering and averaging of epochs of data as required for online classification of ERP responses. It averages over epochs of data that are recorded in response to a number of stimuli; averaging is done separately for each stimulus. When a fixed number of expochs have been accumulated for a given stimulus, the P3TemporalFilter computes their temporal average, and reports the average wave form(s) in its output signal. Whenever a temporal average is reported, the associated stimulus code is reported in the StimulusCodeRes state.

Typically, the P3TemporalFilter's output is sent into the User Reference:LinearClassifier which linearly combines waveform data into a single number. A specialized application module such as the User Reference:P3AV and User Reference:P3Speller modules can then determine which of the stimuli in question was attended.

Parameters

EpochLength

Determines the temporal extent of an epoch. An epoch begins with the onset of its associated stimulus. Epoch length may be specified in blocks as a raw number, or in seconds when immediately followed with a unit: 500ms.

EpochsToAverage

Determines the number of epochs that will be accumulated before reporting their temporal average.

VisualizeP3TemporalFiltering

If nonzero, average waveforms will be presented graphically to the operator user.

TargetERPChannel

For waveform visualization, selects the channel to present in the average waveform display. Channels may be given by ordinal number, or textual label.

States

StimulusCodeRes

When reporting a waveform average, this state contains the associated stimulus code. A StimulusCodeRes value of 0 indicates that the P3TemporalFilter's output does not contain a valid wave form average, and should be ignored by the application module.

StimulusTypeRes

When reporting a waveform average, this state is 1 if the associated stimulus was marked as "attended" on presentation, and 0 if the stimulus was not marked as "attended". In other words, the value of StimulusTypeRes at the time of wave form reporting matches that of StimulusType at the time of stimulus presentation.