[Eeglablist] ersp times: what are these values and how are they formed?

Sean Gilmore sean.gilmore at ryerson.ca
Mon Aug 16 12:13:25 PDT 2021

Dear EEGlab List,

I am using the function 'std_erspplot' to calculate a time frequency decompositions for a specified cluster of dipoles. Data from each participant contains 60 events, with 30 unique triggers (each stimuli was played twice). Each event is epoched into 0sec  - 27.99sec segments. 

I have run the std_erspplot function on a specific cluster using this syntax.

[STUDY erspdata ersptimes erspfreqs pgroup pcond pinter] = std_erspplot(STUDY,ALLEEG,'clusters', cluster)

The output variable ersptimes contains a 1x 200 array of latencies from 0.0559 - 1.4443 * 1.0e+04. This array is peculiar because it does not correspond to the time points that are defined in the epochs (0 - 28sec).

Does anyone know how ersptimes is calculated? What determines the size of this array, and further, why is it is producing this array which doesn’t correspond to the times in the epoch. 

Thanks for your time. Cheers

Sean Gilmore, M.A. (PhD candidate) 
Department of Psychology
Ryerson University

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