Fluid and Crystallized Intelligence
Psychology has long used a framework that splits intellectual work broadly into two kinds. Fluid intelligence is the ability to find a rule on the spot in a problem you have never met before and reason your way through it. Crystallized intelligence is the ability to draw on knowledge, vocabulary, and procedures accumulated over time and put them to use. Recalling a date from history is mostly crystallized work; predicting what comes next in an unfamiliar row of shapes is mostly fluid. The two also change differently with age: crystallized intelligence can keep growing across a lifetime, whereas fluid intelligence is generally held to peak relatively early in adulthood.
Why Shapes
Any attempt to measure fluid intelligence wants tasks that do not depend on language or culture. Problems built out of words turn differences in native language and schooling directly into differences in score. A series of shapes sidesteps that more easily. Changes in attributes such as form, count, orientation, and fill look the same to a speaker of any language. No task is entirely free of culture, of course, but the influence of background is smaller than it is for a vocabulary item. This is why visual reasoning tasks have been placed at the core of intelligence testing.
Raven's Progressive Matrices as the Original Form
The best-known example of a visual reasoning task is Raven's Progressive Matrices, devised in the 1930s. Part of a matrix of shapes is left blank and the examinee selects the item that belongs there from a set of options. The design requires almost no instruction: looking at the item tells you what to do. The format became widely used as an index of non-verbal reasoning and spawned a great many derivative tasks. The shape-series items you come across on the web are usually simplified versions of this original. The defining features of the original - requiring almost no knowledge, demanding that a rule be grasped on first sight - carry over into the simplified versions.
What Happens in Your Head While Solving
Solving a series reasoning item runs several operations in parallel. First you break the figure into its attributes and find which of them is changing. Then you form a hypothesis about how it changes and test that hypothesis against the next element. If the hypothesis fails, you shift attention to a different attribute. Throughout this, the hypotheses formed along the way have to be held in mind, which is why working memory capacity bears heavily on performance. Items in which several rules operate at once feel hard because the number of hypotheses to hold grows and presses against that capacity. The correlation between performance on visual reasoning and performance on memory tasks is thought to arise from this shared foundation.
What a Rising Score Actually Means
Repeat items in the same format and the number of correct answers will reliably go up. The procedure for breaking a figure into attributes becomes second nature, and the rules that appear often get committed to memory. Reading this as 'fluid intelligence has grown' calls for caution, however. Whether the benefits of cognitive training spread beyond the trained task has been debated for a long time, and many reports find such transfer to be limited. The broad view at present is that people do get better at the task they trained on, while transfer to different kinds of problem is small. Treating a rising score as evidence that you have become familiar with this particular task is the reasonable reading.
Putting the Measurement to Work for Yourself
Given all of the above, how to use a pattern reasoning test settles naturally. Rather than comparing yourself with others or treating the result as proof of absolute ability, make it an instrument for measuring repeatedly in the same format and watching your own trend. Record what comes out after a night of short sleep, at the hours when you struggle to concentrate, and under the conditions where you feel at your sharpest, and you accumulate more ways of reading your own state. Bench's Pattern Reasoning test produces no intelligence quotient and puts the gap against your personal best front and center, which follows from exactly this line of thinking. The meaning is in how your own record moves, not in the absolute value of the number.