Cheapest way to measure arousal levels I'm interested in performing a psychological experiment from my own home (the research is controversial; not that it's unethical, but rather I won't be able to aquire funding for it) and in it I would like to measure the arousal level of my participants as accurately and - possibly even more important - as cheaply as possible. I have a regular computer with USB ports, and even though I prefer to work with OS X, I could use Linux, and, if I really was forced to, even Windows.

I'm thinking that galvanic skin response is the best measure because of the method's temporal responsiveness, but I guess heart rate could be used as well.

Does anybody know of any good and cheap instruments that can a) measure arousal level and b) can be connected to a regular computer?
I think you may have answered your own question.

You can build a GSR meter or purchase one online. You do not necessarily need to hook it up to your computer; if it has an LED you can simply record the results with pen and paper. If you want to measure heart rate, buy a stethoscope. Or if you want to be really cheap, check your pulse using two fingers; it's free.

Note that I have no experience with building my own GSR meter or using the GSR meter that I've linked to. I cannot vouch for the accuracy or reliability of these devices. The familiar adage is probably appropriate: you get what you pay for.