Grating Orientation Threshold
Estimate grating-orientation threshold by interpolation in log groove width at a supplied probability criterion; unlike linear two-point separation interpolation.
Description
A grating-orientation threshold is a groove width reaching a selected correct-response criterion.
A grating-orientation threshold is a groove width reaching a selected correct-response criterion. Log-width interpolation treats multiplicative spacing as the interpolation scale.
The tool returns thresholdGrooveWidthMm (threshold groove width mm). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.
When to use Grating Orientation Threshold
Use Grating Orientation Threshold when you already have grooveWidthsMm, correctFractions, criterionFraction and want thresholdGrooveWidthMm. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.
How to use Grating Orientation Threshold and understand its results
- Enter grooveWidthsMm, correctFractions, criterionFraction using the field table below. Match the units, ordering and data boundaries described in the calculation.
- Run the tool after checking the stated bounds and matching paired observations or categories. A malformed request gives a tool error rather than a usable measurement.
- Read thresholdGrooveWidthMm. Use the calculation and interpretation below to distinguish amounts, ratios, signs and decision flags where applicable.
- Review the supplied parameters and assumptions before using the result in a report or comparing it with another observation.
| Input field | Meaning | Value type and bounds | Requirement |
|---|---|---|---|
| grooveWidthsMm | Groove widths mm | list of number | Required |
| correctFractions | Correct fractions | list of number | Required |
| criterionFraction | Criterion fraction | number | Required |
Require increasing positive widths and nondecreasing response fractions. Find the first bracket crossing the criterion and interpolate in log width.
width = exp(ln(lowWidth)+fraction×ln(highWidth/lowWidth)) The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.
{
"input": {
"grooveWidthsMm": [
0.5,
1,
2
],
"correctFractions": [
0.5,
0.75,
1
],
"criterionFraction": 0.875
},
"output": {
"thresholdGrooveWidthMm": 1.414213562373095
}
}Limitations and assumptions
A criterion already met at the first width or never reached is rejected. No psychometric fitting or extrapolation is performed.
Numerical inputs must be finite. The tool checks its declared input shape and calculation constraints; those checks do not verify the quality, calibration or representativeness of the supplied observations.
Alternative or Complementary methods
Two-Point Discrimination: Interpolate a two-point tactile discrimination criterion from monotone trial-count psychometric data; out-of-range criteria remain unestimated. Psychometric Function Slope: Evaluate a logistic psychometric response and local derivative with explicit guessing, lapse, midpoint and stimulus-unit scale.
Methodological background: The psychometric function: fitting, sampling, and goodness of fit.1
References
-
The psychometric function: fitting, sampling, and goodness of fit — Wichmann and Hill; Perception & Psychophysics
Similar or alternative tools
- Two-Point Discrimination
Interpolate a two-point tactile discrimination criterion from monotone trial-count psychometric data; out-of-range criteria remain unestimated.
- Psychometric Function Slope
Evaluate a logistic psychometric response and local derivative with explicit guessing, lapse, midpoint and stimulus-unit scale.