[Eeglablist] Question about sorting epochs

[Renzo Lanfranco]

Dear EEGLAB community,

I was wondering if you could help me with something. I have EEG datasets that need an unconventional treatment before analysis. In this experiment, participants hear a beep (event 1), and 2 seconds later, a series of 5 stimuli are shown, with 1 second of separation in between (events from 2 to 6). After pre-processing and epoching, epochs with event label 1 are 2000 ms long (from 0 to 2000 ms, no stimulus) and the other epochs are 1000 ms long (from -500 to +500 ms, where time zero indicates stimulus presentation).

How can I average across all the epochs with event label 1, 2, 3, 4, 5, and 6, and then copy the epochs with event label 1 to every other epoch so the resulting epochs are 2000 ms (duration of epoch 1) + 1000 ms (duration of each stimulus epoch)? Thus, we’d have resulting epochs of -2000 ms to +1000 ms. The objective is to use the epoch with event number 1 as baseline for the stimulus-related epochs (event numbers 2, 3, 4, 5, and 6).

Thank you so much!

Best,
Renzo