They test for puzzles that appear as visual shape complexities which require use of the visual cortex. That is something a person might refer to as a visual abstraction. That isn't a practical abstraction, such as requiring a person to form an answer from the absent of acceptable criteria (to abstract or form something new to solve a problem).

It means a bias of coming together toward a tester's preferences. Do people excel on the few narrow performance meausures you find most correlated with intelligence?

There are divergent aptitude tests measure quantity and diversity of answers to a given question opposed to the one desired answer. Divergent tests are rarely performed, but at a stronger measure of creativity and problem solving which is typically what people actually want when they say intelligence. The reason why convergent testing is preferred over divergent test is because it is easier to measure and those simplified measures are easier to compare.