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Event-related potentials (ERPs)

Event-related potentials (ERPs). Jarrod Blinch motorbehaviour.wordpress.com May 31 st , 2011. Type of electrodes. Non- polarised silver-chloride (Ag/ AgCl ) Tin Gold or platinum. How many trials?. EEG 50 uV ERPs 60 trials for large component (~10 uV , P300, RP/LRP)

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Event-related potentials (ERPs)

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  1. Event-related potentials (ERPs) Jarrod Blinch motorbehaviour.wordpress.com May 31st, 2011

  2. Type of electrodes • Non-polarised silver-chloride (Ag/AgCl) • Tin • Gold or platinum

  3. How many trials? • EEG 50 uV • ERPs • 60 trials for large component (~10 uV, P300, RP/LRP) • 150 medium (~5 uV) • 400 small (~1-2 uV)

  4. Overview • Event-related potentials (ERPs) • Advantages and disadvantages • ERP components and waveform peaks • Strategies to interpret ERP components • Quantifying noise • Components • Readiness potential (RP, LRP) • P300 (P3a, P3b) • Fractionating information processing • Osman and Moore, 1993 (LRP) • Luck, 1998 (P3b)

  5. Event-related potentials (ERPs) • Averaging to generate ERPs • Tiny effects • Relying on previous ERPology • Reliability • Low within-participant variability • High between-participant variability

  6. Advantages and disadvantages Advantages Disadvantages Functional significance Tiny effects Spontaneous or induced potentials Spatial resolution Peaks versus components… Latency jitter… • Continuous measure of processing • Independent of a behavioural response • Evoked or emitted potentials • Noninvasive • Temporal resolution

  7. Imperative stimulus Response initiation Reaction time

  8. ERP components and waveform peaks

  9. Strategies to interpret ERP components • Focus on a specific component • Use well-studied experimental manipulations • Focus on large components • Isolate components with difference waves • Focus on components that are easily isolated • Use component-independent experimental designs • Hijack useful components from other domains

  10. Quantifying Noise

  11. Overview • Event-related potentials (ERPs) • Advantages and disadvantages • ERP components and waveform peaks • Strategies to interpret ERP components • Quantifying noise • Components • P300 (P3a, P3b) • Readiness potential (RP, LRP) • Fractionating information processing • Osman and Moore, 1993 (LRP) • Luck, 1998 (P3b)

  12. P300

  13. Readiness potential (RP) MP Late RP Early RP

  14. Lateralised readiness potential (LRP)

  15. Imperative stimulus Response initiation LRP P300 Reaction time

  16. Psychological refractory period

  17. Bottleneck Stimulus onset asynchrony (SOA)

  18. Osman & Moore, 1993 LRP

  19. L * *

  20. Luck, 1998 P300

  21. Event-related potentials (ERPs) Jarrod Blinch motorbehaviour.wordpress.com May 31st, 2011

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