Advanced search multiple-select boxes should be check boxes or highlight-select

[DominicBM]

This is not the most user-friendly way to handle multiple-selection:

These fields could be checkboxes, so it's a clearer visual cue that multiple list items can be selected. This would match the data source selection. Or, alternatively, we could go with highlight-selection, like the refinement sidebar in the search results. e.g.:

[WaxCylinderRevival]

The Getty Research Institute has checkboxes for "Include" and "Exclude" in search refinements (for use with multiple selections; the default is non-selection for these options) that could be very interesting to incorporate in our advanced search.