Neural Mechanisms of Social Feedback Evaluation in Young Adults Across the Schizotypy Spectrum: An EEG Social Judgment Study

Participants complete a single-session Social Judgment Paradigm during EEG recording. All participants experience four within-subject experimental conditions defined by feedback expectancy (expected versus unexpected) and feedback valence (acceptance versus rejection): expected acceptance, expected rejection, unexpected acceptance, and unexpected rejection. The order of feedback trials is randomized within the task.

A computerized Social Judgment Paradigm in which participants receive experimentally controlled social feedback (acceptance/rejection) from purported peers or evaluators while continuous EEG is recorded to assess oscillatory activity and event-related potentials associated with social feedback processing. Feedback valence and expectancy are manipulated at the trial level, with trial order randomized within the task.

• SJP

Mean frontal-midline theta-band power (4-7 Hz) derived from EEG data time-locked to feedback onset during the Social Judgment Paradigm, quantified during the prespecified 200-600 ms post-feedback window at frontocentral electrodes. Theta power will be measured directly across the four feedback conditions defined by expectancy (expected/unexpected) and feedback valence (acceptance/rejection).

Mean event-related potential (ERP) amplitude within the 250-350 ms time window following feedback onset during the Social Judgment Paradigm, quantified at frontocentral electrodes. FRN amplitude will be measured directly across the four feedback conditions defined by expectancy and feedback valence.

Mean event-related potential (ERP) amplitude within the 350-600 ms time window following feedback onset during the Social Judgment Paradigm, quantified at midline electrodes. LPP amplitude will be measured directly across the four feedback conditions defined by expectancy and feedback valence.

Participant predictions of social acceptance or rejection during each trial of the Social Judgment Paradigm, including expectancy response and reaction time.

The Schizotypal Personality Questionnaire (SPQ) is a 74-item self-report measure assessing schizotypal personality traits across cognitive-perceptual, interpersonal, and disorganized dimensions. Items are answered in a yes/no format and scored dichotomously. Item scores are summed to produce a total score ranging from 0 to 74. Higher scores indicate greater levels of schizotypal personality traits.

The Multidimensional Schizotypy Scale (MSS) is a 77-item self-report measure assessing positive, negative, and disorganized dimensions of schizotypy. Items are answered using a true/false response format. The Positive Schizotypy subscale contains 26 items and ranges from 0 to 26; the Negative Schizotypy subscale contains 26 items and ranges from 0 to 26; and the Disorganized Schizotypy subscale contains 25 items and ranges from 0 to 25. Higher scores on each subscale indicate greater levels of the corresponding dimension of schizotypy.

The Brief Fear of Negative Evaluation Scale-Revised (BFNES-R) is a 12-item self-report measure assessing fear of negative evaluation by others. Each item is rated on a 5-point Likert scale ranging from 0 (not at all characteristic of me) to 4 (extremely characteristic of me). Item ratings are summed to produce a total score ranging from 0 to 48. Higher scores indicate greater fear of negative evaluation and greater concern about others' social evaluation.

The Perceived Stress Reactivity Scale (PSRS) is a 23-item self-report measure assessing an individual's typical response intensity to potentially stressful situations in everyday life. The scale includes five domains: prolonged reactivity, reactivity to failure, reactivity to social conflict, reactivity to work overload, and reactivity to social evaluation. Items are scored from 0 to 2, with negatively keyed items reverse-scored, and summed to produce a total score ranging from 0 to 46. Higher scores indicate greater perceived stress reactivity

The Social Functioning Questionnaire (SFQ) is an 8-item self-report measure assessing perceived social functioning across domains including work and home activities, finances, close relationships, family relationships, social isolation, sexual functioning, and leisure activities. Each item is scored from 0 to 3, and item scores are summed to produce a total score ranging from 0 to 24. Higher scores indicate poorer social functioning.