If I first had to group White items with pleasant words and later had trouble grouping Black items with pleasant words, could my test score have been the result of this task order?
The order in which tests are administered does make a difference, but not a large one (and it rarely changes the direction of the outcome). Because of this difference, tests on this web site randomize the order of presentation. To check whether the order made a difference in your case, you can take the test a few more times and see what your score is when the order is reversed. If your score changes depending on the order of presentation, the best estimate of your result is somewhere in the middle.
