Olfactory Threshold
Detect directional staircase reversals and average the caller-selected last reversals for an olfactory dilution-step threshold; concentration calibration is external.
Description
Staircase reversals occur when the direction of stimulus adjustment changes.
Staircase reversals occur when the direction of stimulus adjustment changes. Averaging recent reversal levels provides a threshold summary of a completed staircase.
The tool returns reversalIndexes (reversal indexes); meanReversalStep (mean reversal step). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.
When to use Olfactory Threshold
Use Olfactory Threshold when you already have dilutionSteps, reversalsToAverage and want reversalIndexes, meanReversalStep. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.
How to use Olfactory Threshold and understand its results
- Enter dilutionSteps, reversalsToAverage 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 reversalIndexes, meanReversalStep. 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 |
|---|---|---|---|
| dilutionSteps | Dilution steps | list of number | Required |
| reversalsToAverage | Reversals to average | integer | Required |
Ignore repeated levels when identifying direction. Record the last moving index before each direction change and average the requested number of final reversals.
threshold step = mean(last k reversal levels) The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.
{
"input": {
"dilutionSteps": [
1,
2,
3,
2,
1,
2,
3,
2
],
"reversalsToAverage": 3
},
"output": {
"reversalIndexes": [
2,
4,
6
],
"meanReversalStep": 2.3333333333333335
}
}Limitations and assumptions
Indexes are zero-based, and insufficient reversals fail. Dilution steps are not converted to physical concentration or an adaptive protocol.
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. Grating Orientation Threshold: Estimate grating-orientation threshold by interpolation in log groove width at a supplied probability criterion; unlike linear two-point separation interpolation.
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.
- Grating Orientation Threshold
Estimate grating-orientation threshold by interpolation in log groove width at a supplied probability criterion; unlike linear two-point separation interpolation.