I'm most likely (rotating now) doing my PhD in computational immunology. I am curious as to how feasible it is to do a postdoc in a different scientific field--I was thinking along the lines of mathematical (computational) psychology. I wouldn't think it would be too out there, but it'd be nice to get a feel of the probability of that happening.

 

Any response is much appreciated.

Technically, it is possible. This is especially true, if you know someone to introduce you to a given group, or if you directly know the PI. If you are an unknown quantity it is still feasible, however you are likely to have more chances if you got some own money (e.g. a postdoc grant). It is less likely to get a position in a different field that requires working on a running grant with looming deadlines, unless you can demonstrate that your acquired abilities can be transferred to that particular topic.

 

Note that depending on what your goal is it may not be wise to change fields too much (I am not familiar with either discipline and your invovlement in them, so I cannot evaluate how far a stretch it would be). You want to be able to establish yourself in a particular field, if your goal is an academic career, for instance.