---
title: "Pupil Measurement Boundaries in Multimodal IRT"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Pupil Measurement Boundaries in Multimodal IRT}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(collapse = TRUE, comment = "#>")
library(eyeprocess)
```

## Why pupil needs a measurement layer

The 0.10 development simulator explicitly separates a neutral pupil
responsivity dimension from nuisance effects of luminance and gaze position.

```{r}
sim <- simulate_multimodal_irt(
  n_person=80, n_item=12, seed=21,
  pupil_luminance=-.25,
  gaze_x_effect=.10,
  gaze_y_effect=-.06
)
summary(sim$data[c("pupil_response","luminance_z","gaze_x_z","gaze_y_z")])
```

```{r}
plot(sim, type="channel_distributions")
```

The presence of a pupil effect does not establish cognitive load, effort, or
arousal.