[chinpokomon]

Although others that have responded to this thread have far more experience, I believe Peltiers are optimized to work in one direction. That is to say there is a hot and cold side, so I'm not sure it is as simple as adding an inverter. Not that you'd likely be using your hands as a heat sync anyway.

Yes, I realize this was meant as a joke, but I'm still curious if current can be reversed by just changing the gradient. Does it still work but maybe it is less efficient? Is there no difference at all?

[schiffern]

Ah, good point. I hadn't considered that. It looks like you are correct! You might sandwich two Seebeck-Peltier devices and switch between them, though.

https://en.wikipedia.org/wiki/Thermoelectric_effect