Saccade Latency

Interpolate the first supplied eye-speed threshold crossing after a cue; blink rejection and direction classification are not inferred.

Description

Saccade latency can be defined by the first speed-threshold crossing after a cue.

Saccade latency can be defined by the first speed-threshold crossing after a cue. Interpolating a crossing uses both adjacent samples.

The tool returns saccadeOnsetMs (saccade onset ms); latencyMs (latency ms). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.

When to use Saccade Latency

Use Saccade Latency when you already have timesMs, speedsDegreesPerSecond, cueTimeMs, onsetSpeedDegreesPerSecond and want saccadeOnsetMs, latencyMs. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.

How to use Saccade Latency and understand its results

Enter timesMs, speedsDegreesPerSecond, cueTimeMs, onsetSpeedDegreesPerSecond 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 saccadeOnsetMs, latencyMs. 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
timesMs	Times ms	list of number	Required
speedsDegreesPerSecond	Speeds degrees per second	list of number	Required
cueTimeMs	Cue time ms	number	Required
onsetSpeedDegreesPerSecond	Onset speed degrees per second	number	Required

Use nonnegative speeds, a positive threshold and ordered aligned times. Search from the cue and interpolate the first upward crossing; an already-exceeded threshold or absent crossing is rejected.

latencyMs = interpolatedOnsetMs−cueTimeMs

The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.

json

{
  "input": {
    "timesMs": [
      0,
      10,
      20,
      30
    ],
    "speedsDegreesPerSecond": [
      0,
      0,
      100,
      100
    ],
    "cueTimeMs": 10,
    "onsetSpeedDegreesPerSecond": 50
  },
  "output": {
    "saccadeOnsetMs": 15,
    "latencyMs": 5
  }
}

Limitations and assumptions

The caller supplies speeds and threshold; no eye-position differentiation, smoothing or trial classification occurs.

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

Saccade Velocity: Derive planar eye-path speeds from timestamped horizontal/vertical angles; finite-difference peaks are cadence-limited and not instantaneous physiological peaks. Pupillary Light Reflex Latency: Find the interpolated first pupil constriction threshold crossing after a stimulus using supplied baseline and amplitude criterion; missing crossings return an error, not a fabricated latency.

Methodological background: Digital Library of Mathematical Functions: Quadrature.^[1]

References

Digital Library of Mathematical Functions: Quadrature — National Institute of Standards and Technology

Similar or alternative tools

Saccade Velocity
Derive planar eye-path speeds from timestamped horizontal/vertical angles; finite-difference peaks are cadence-limited and not instantaneous physiological peaks.
Pupillary Light Reflex Latency
Find the interpolated first pupil constriction threshold crossing after a stimulus using supplied baseline and amplitude criterion; missing crossings return an error, not a fabricated latency.