Are there certain colors we should use when highlighting selected items in a GUI?

Question

One part of my application allows users to select items in order to manipulate the items, and I want to put a border around the items with a color to show when it's selected.

Normally the users will select one item (i.e., delete item) or two items (i.e., move item one after item two) only.

I was thinking that one color would represent the first selected item, and a second color would represent the second item, so as to not confuse the two items selected This is especially important in the case of moving one item to the position after the another item, where it's important to know which item is moving after the other.

My questions are.

1. Should each item have their own selected color, or should the same color be used for both items?

2. Are there certain colors that are preferred, over other colors to use when selecting items? i.e., green over red.

NOTE: I wanted to mention that I'm not exactly highlighting the entire item, but merely adding a colored border around the item, so the items will still look the same, besides a 2px or so border around the item.

Answer 1

Use same color for selection that will reduce cognitive load unless you want to show a queue of selected items based on selected time. If your intention is to show a queue then choose the color that suits your application theme, but don't mix it with multiple colors - you can use shades of one color such as; dark for the first and little faint for the second and so on.

Don't just rely on colors - think about color-blind users, they won't see any change if you only change colors.

Along with color change also consider changing the dimensions of the selected items - like making the selected items a little larger than the rest.

Answer 2

Choice of colors depends on nature / industry of your application. But pale yellow for first selection and light blue for other will be good in your case.