Description
Return location+scale×ln((target-guess)/(1-lapse-target)).
A stimulus model relates a chosen level to a supplied response curve, geometry or adaptive rule. One inverse curve or staircase step can be computed without fitting observations, measuring perception or establishing an individual's threshold.
Return location+scale×ln((target-guess)/(1-lapse-target)).
When to use this tool
Use Psychometric Threshold Supplied Curve Inverse when you need the stated stimulus-model or adaptive-step calculation.
How to use the tool and how it works
- Enter targetProbability, guessRate, lapseRate, location, scale. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read threshold. Use the output convention below.
Require guess/lapse fractions, positive scale and target strictly between guessRate and 1-lapseRate. Return location+scale×ln((target-guess)/(1-lapse-target)).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| targetProbability | Target Probability | Required. Finite number. |
| guessRate | Guess Rate | Required. Finite number; minimum 0; maximum 1. |
| lapseRate | Lapse Rate | Required. Finite number; minimum 0; maximum 1. |
| location | Location | Required. Finite number. |
| scale | Positive logistic scale in the same stimulus unit as location and threshold. | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| threshold | Threshold | Required. Finite number. |
{
"input": {
"targetProbability": 0.75,
"guessRate": 0.5,
"lapseRate": 0,
"location": 10,
"scale": 2
},
"output": {
"threshold": 10
}
}Limitations and assumptions
- This inverts a supplied logistic psychometric curve with lower/upper asymptotes. It does not fit observations, estimate uncertainty or establish a clinical threshold.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Fit and validate the appropriate model on the study data when estimating a threshold. Review lapse/guess assumptions, calibration, convergence, uncertainty and participant context.
References
Similar or alternative tools
- Psychometric Lapse Guess Asymptote Gap
Return guess and 1-lapse asymptotes and guess+(1-guess-lapse)×latent.
- Staircase One Up Down Step Response
Subtract down step for correct or add up step otherwise, then clamp nextLevel to bounds.