Eventrelated potentials ERPs Jarrod Blinch motorbehaviour wordpress com

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

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

How many trials? • EEG 50 u. V • ERPs – 60 trials for large component (~10 u. V, P 300, RP/LRP) – 150 medium (~5 u. V) – 400 small (~1 -2 u. V) 3

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) – P 300 (P 3 a, P 3 b) • Fractionating information processing – Osman and Moore, 1993 (LRP) – Luck, 1998 (P 3 b) 4

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

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Advantages and disadvantages Advantages Disadvantages • Continuous measure of processing • Independent of a behavioural response • Evoked or emitted potentials • Noninvasive • Temporal resolution • Functional significance • Tiny effects • Spontaneous or induced potentials • Spatial resolution • Peaks versus components… • Latency jitter… 11

Imperative stimulus Stimulus identification Response initiation Response selection Reaction time Response programming 12

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ERP components and waveform peaks 14

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Strategies to interpret ERP components 1. 2. 3. 4. 5. 6. 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 7. Hijack useful components from other domains 18

Quantifying Noise 19

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Overview • • • Event-related potentials (ERPs) Advantages and disadvantages ERP components and waveform peaks Strategies to interpret ERP components Quantifying noise Components – P 300 (P 3 a, P 3 b) – Readiness potential (RP, LRP) • Fractionating information processing – Osman and Moore, 1993 (LRP) – Luck, 1998 (P 3 b) 22

P 300 23

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Readiness potential (RP) MP Late RP Early RP 26

Lateralised readiness potential (LRP) 27

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Imperative stimulus LRP P 300 Stimulus identification Response selection Reaction time Response initiation Response programming 29

Psychological refractory period 30

Bottleneck Stimulus onset asynchrony (SOA) 31

Osman & Moore, 1993 LRP Stimulus identification Response selection Response programming Stimulus identification Bottleneck Response selection Response programming Stimulus identification Response selection Bottleneck Response programming 32

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Luck, 1998 P 300 Stimulus identification Response selection Stimulus identification and Bottleneck Stimulus identification Response programming Response selection and Bottleneck Response programming 36

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