ERP Experiment Analysis
ERP Experiment Analysis allows you to add target markers to your selected data recordings.

Slew limit

You can set a slew rate limit to control the EEG signals between successive samples, up to a maximum value. Large voltage step changes from one sample to the next sometimes occur due to electrostatic discharge from the subject (participant), headset movements, or other artifacts. The effect of voltage step changes on filtered signals, and fast Fourier transform (FFT) epochs can artificially persist for a long time after the event. Setting a maximum slew rate limits the extent of step changes and reduces its impact without significantly affecting the EEG signal components. The default slew rate in Analyzer is 30 microvolts. However, you can enter any positive value here.

Referencing

The data processed by Analyzer can be referenced to an aggregate of all the data selected. The available aggregate functions are:
  • Mean
  • Median
  • Interquartile mean
  • None (deactivates re-referencing)

Filter Coefficients

Default values are set for you. However, you can change these values if you want to.
If you do not know what you are doing, please use the default values. The default values are shown below.

Target Markers

For ERP analysis, you can add one or more target markers.
First you must give your target marker(s) a name. Then you must select either Value or Label:
  • If you select Value, you must input a numerical value.
  • If you select Label, you must input a description, like ‘high’.
By clicking on the + icon you can add more target markers. You can delete a target marker by clicking on the trash bin icon next to it.

Time Before and Time After

Time Before and Time After allows you to input a time before and after a marker (in seconds) in your EEG data. Adding time before and after a marker provides a ‘buffer’ around what is taken into account while Analyzer processes your EEG data.
Once you’ve input the ranges you need for ERP analysis, click on Start.

Results

While your data is processing, the results page will open. The results page provides information about the jobs processed in Analyzer, including Job Name, Date Created, Status, and Actions.
Once Analyzer has finished processing your data, its status will change from Processing to Complete.
If the status doesn’t say ‘Complete’ within a few seconds, click on the Refresh button at the bottom right-hand corner of the screen.
You can download the completed data as a ZIP file and save it locally. To do this, click on the Results button.