[Eeglablist] Average re-reference

[Chiara Terzo]

Dear all,


I estimated evoked-potentials of an EEG data set collected with 32 channels. With the reference to the right mastoid I get a specific pattern of evoked that are consistent with the previous literature (i.e. positive late potentials around 400ms). However, if before doing ICA I re-reference my data to the common average (as it's highly recommended), I get a different pattern, such as late potentials  being negative. Which one of the two should then be reliable? Is it necessary to re-reference to average before doing ICA? And how much not doing so would bias my results?


Thank you for your help,


Chiara