I don't think donations have a significant correlation with spending or saving behaviours.
The motivation behind donating is very different from the motivation behind spending.
I (and proponents of the "deflationary danger" theory) speak of the motivation to
not spend, not
to spend. The presumed disincentive to spend should also apply to donating.
No. That would still imply that the motivation of donating would only vary on the bipolar spectrum of having vs not having the money.
I believe that there is another factor when it comes to donating that has a much more prevalant influence - belief, activism, humaneness, politics, call it what you want, but it's not primarily economic in nature.