Analysis method
Psychometric profile
Joint estimation of response probability across stimulus conditions.
Input
Trial-level stimulus values, conditions, responses, and participant identifiers.
Model
Fit a preregistered psychometric function across conditions. Compare the specified curve with a simpler model that omits the proposed bend or change point.
Results
Report threshold or change point, slope, lapse rate, interval estimates, model comparison, and condition-level observations.
Validity
Do not report a change point when the simpler model is adequate or when its interval spans the tested range.