They need to add heater packs underneath and thermocouple readings. While white is good at rejecting external thermal radiation, it is also poor at emitting thermal radiation. A white surface can be hard to keep cool if the heat comes from within. In particular, white will look like it has a much better comparitive advantage when imaged in IR than is likely to be the case in real usage conditions.
Yellow, red, and gray may be more comfortable in practice.
But most heat we reject isn’t rejected radiatively, so you need a sweaty heater pack for a better test. You’re right that the clothes will also affect how well the person underneath removes heat, a confounding variable, but pigment alone might be a small part compared to weave and fiber choices
They need to add heater packs underneath and thermocouple readings. While white is good at rejecting external thermal radiation, it is also poor at emitting thermal radiation. A white surface can be hard to keep cool if the heat comes from within. In particular, white will look like it has a much better comparitive advantage when imaged in IR than is likely to be the case in real usage conditions.
Yellow, red, and gray may be more comfortable in practice.
But most heat we reject isn’t rejected radiatively, so you need a sweaty heater pack for a better test. You’re right that the clothes will also affect how well the person underneath removes heat, a confounding variable, but pigment alone might be a small part compared to weave and fiber choices