Event-related potential paradigms for delay discounting in schizophrenia: Five paradigms and a methodological roadmap

Table 1 Literature inclusion and exclusion criteria

No.	Inclusion criteria	Exclusion criteria
1	Human participants	Non-human subjects (e.g., animal experiments)
2	Research involving delay discounting or delay discounting tasks	Absence of a delay discounting task
3	Use of ERP techniques	Studies in non-schizophrenia populations that did not employ ERP during a delay discounting task
4	Original empirical research	Non-original studies (e.g., reviews, commentaries, editorials, book chapters, conference abstracts)
5	Fulltext availability	Fulltext unavailable

ERP: Event-related potential.

Table 2 Summary of major event-related potentials components in delay discounting tasks

ERP	Time window	Typical electrode sites	Functional significance	Typical findings in delay discounting tasks
CNV	Cue-to-response (sustained slow potential)	Frontocentral (Fz, Cz)	Anticipatory preparation, motivational engagement	Larger CNV for delay-escape vs delay-inescapable conditions
P200	150-250 millisecond	Frontocentral (Fz, FCz)	Early attentional allocation	Greater amplitude in loss vs gain context; larger for delayed vs immediate options
N2	200-350 millisecond	Frontocentral (Fz, FCz)	Conflict monitoring, cognitive control	Increased amplitude under high conflict; negatively correlated with immediate choice rate
RewP/FRN	250-350 millisecond	Frontocentral (FCz)	Reward value encoding, outcome evaluation	Larger for immediate than delayed rewards; high discounters show larger RewP for immediate rewards
P300	300-500 millisecond	Parietal (Pz, P3, P4)	Attentional resource allocation, motivational salience, subjective value representation	Amplitude decreases with longer delays; larger for delayed than immediate choices
LPP	400-900 millisecond	Parietal (Pz, CPz)	Sustained emotional and motivational processing	Sensitive to probability; larger in loss context; larger for immediate vs delayed rewards
Theta	4-8 Hz (time-frequency)	Frontocentral	Decision conflict, cognitive control	Increased theta power after immediate choices in low discounters; higher theta during impulsive choices
Beta	13-30 Hz (time-frequency)	Frontal	Cognitive resource allocation, “cool” system processing	Lower beta power in the time-overestimation group; increased beta during non-impulsive choices

ERP: Event-related potential; CNV: Contingent negative variation; Fz: Frontal zero; Cz: Central zero; RewP: Reward positivity; FRN: Feedback-related negativity; FCz: Fronto-central zero; Pz: Parietal zero; CPz: Centro-parietal zero.

Table 3 Summary of event-related potentials paradigms for delay discounting studies

Paradigm	Key parameters	Primary ERP components	Remarks for schizophrenia applicability
Classical hypothetical delay discounting task	Binary choice between SS vs LL; delays ranging from 1 day to 6 months; parametric variation of reward amounts; Kirby titration or McClure orthogonal design	P300, RewP, CNV, N2, P2	Clear behavioral phenotype (elevated discounting) and well-documented P300 abnormalities; no direct ERP study yet; recommended as firstchoice paradigm
Delay discounting with risk	Simultaneous manipulation of delay (short/Long) and probability (high/Low); typically a 2 × 2 design	N1, P2, N2, N400, LPC, P300	Allows dissociation of risk and time discounting; suitable for examining probabilistic reasoning biases
Emotionprimed intertemporal choice	Presentation of emotional pictures/faces (e.g., disgust, anger, gratitude) before each choice; pre-rating of valence and arousal recommended (e.g., IAPS/CAPS)	N1, P2, P3, LPP, SPN, EPN	Useful for studying interaction between affective processing and decisionmaking; can explore negative symptom mechanisms (anhedonia)
Loss-framed intertemporal choice	Monetary losses instead of gains; symmetric design with gain frame to compare gain-loss asymmetry	P2, N2, P3	Reveals asymmetry of loss aversion; suitable for testing emotion regulation deficits
Social distance/social comparison intertemporal choice	Decisions for self, friend, or stranger; may include social comparison feedback	N1, P2, P3 (P3a/P3b), LPP	Explores the neural basis of social cognition deficits; recommended for patients with relatively preserved cognitive function

ERP: Event-related potential; SS: Smaller-sooner; LL: Larger-later; RewP: Reward positivity; CNV: Contingent negative variation; LPC: Late positive component; IAPS: International affective picture system; CAPS:Chinese affective picture system; LPP: Late positive potential; SPN: Stimulus preceding negativity; EPN: Early Posterior negativity.