Assumption of averaging ERP implying. gn sga→DA→[B signal A 3 ubject 1 signal A subject 3 2 jga→[A」 B sign B→ 0 40060m0100012001400 Oms 200ms 400ms Reaction time(ms) Identical processes in each realization Contradictory to strong response variability 1/28/2021
A A A A A A B B B B B B C C C C C C signal signal signal signal signal signal output output output output output output … … … … … … Identical processes in each realization; Contradictory to strong response variability Assumption of averaging ERP implying… 0ms 200ms 400ms 600ms 800ms 1000ms 1/28/2021 6
Alternative assumption about brain response signal output signal 1=A B C output sgna→[A output gna >A sIg output signal一 A→>B output signal A output Oms 200ms 400ms 600ms 800ms 1000ms Latency jitters in each realization 1/28/2021
Alternative assumption about brain response A A A A A A B B B B B B C C C C C C signal signal signal signal signal signal output output output output output output … … … … … … 0ms 200ms 400ms 600ms 800ms 1000ms Latency jitters in each realization 1/28/2021 7
Reality: systematic variability in the EEG data stimulus onset reaction Times Sorting by rT stimulus reaction time WAAM 900ms Electroencephalographic(EEG) What is the consequence of latency variability on ERP? 1/28/2021 8
Reality: systematic variability in the EEG data time trial index 100 300 500 700 900 ms 20 40 60 80 100 120 140 160 stimulus onset reaction Times 1/28/2021 8 What is the consequence of latency variability on ERP? Sorting by RT
atency variability: Smearing effect (convolution s(t) TXXXXXWX s(t*p(t) Generally the convolution reduces the amplitude When the spreading'distribution is broad the convolution approaches to zero 1/28/2021
Latency variability: Smearing effect (convolution) 𝑆 𝑡 𝑆 𝑡 ∗ 𝜌(𝑡) ➢Generally, the convolution reduces the amplitude ➢When the ‘spreading’ distribution is broad, the convolution approaches to zero 1/28/2021 9
Stimulus Trial 1 1 0 ms 1800ms Trial 2 Oms 1800ms Limitations of average ERP method Smearing and mixing of components Limited precision of amplitude/ latency and conditional effects Vague interpretation in mental chronometry Lose valuable single trial dynamic information A possible solution? Average erp Oms 1800ms 1/28/2021
Stimulus . . . 0ms 1800ms 0ms 1800ms 0ms 1800ms 0ms 1800ms 0ms 1800ms Trial 1 Trial 2 Trial 3 Trial i Average ERP Limitations of average ERP method ➢ Smearing and mixing of components ➢ Limited precision of amplitude/latency and conditional effects ➢ Vague interpretation in mental chronometry ➢ Lose valuable single trial dynamic information A possible solution? 1/28/2021 10