Stimulus type protocol | Spatial arrangement | Surface area | Circumference | Density |

Standard | Randomized^{†} | Increasing with quantity | Increasing with quantity | Increasing with quantity |

Equal area and equal density | Randomized^{†} | Equal across quantity | Increasing with quantity | Equal across quantity^{‡} |

Equal circumference | Randomized^{†} | Decreasing with quantity | Equal across quantity | Increasing with quantity |

Linear | One-dimensional, linear | Increasing with quantity | Increasing with quantity | Increasing with quantity |