The whole battery of mental abilities tests was never applied on a bigger sample. But still in separate studies a considerable amount of results was obtained, mainly in terms of correlations among tests. See the descriptions of test in the Tests of mental abilities chapter.

The advantage of these studies, conducted on candidates for jobs, was a great motivation of people and very heterogeneous samples. This resulted in some quite high correlations, which are a real reflection of relations among mental abilities.

Correlation studies

The broad visual factor:

On table below correlations among predominantly visual tests are shown. In the diagonal, there are reliabilities of tests, above it correlations and below it numbers of people in samples. There were of course not all the same people in different samples.

Although Series is a reasoning test, it correlates with other visual tests similarly as they do among themselves.

Correlations of visual tests with tests from other broad mental abilities clusters are lower: between 0.24 in 0.49.

Information processing and working memory

In one of studies factor analysis clearly showed the difference between the memory span factor and the nonverbal reasoning factor.

We can see, that a task, in which one must repeat numbers, shown on screen in succession in mixed order, still to a greater degree measures memory span than reasoning. Vice versa is true for tasks, in which a series of numbers must be kept in working memory and it's proper continuation is to be found. We can see also, how the involvement of working memory grows. In repeating numbers in the reverse order, it is minimal, in repeating them in mixed order it is already considerable, and in reasoning it is highest.

In the second study factor analysis clearly showed the difference between memorizing abilities and central processing abilities.

The first factor is reasoning and, interestingly, we can see, that the highest saturation on it has a working memory test. The second factor is memorizing. We can see, that memory span is not an ability, which would relate much with memorizing.

In my studies classical nonverbal reasoning tests correlate highly among themselves. For example: The longer version of Series test correlates with the famous Domino-48 test 0.73, and the shortest version of Series test correlates with the Purdue test 0.70.

Different results were obtained by the interesting Codes test, which is very hard and not time-limited. It also correlates highest with the Series test but the correlation is still only 0.45.

The broad memorizing factor:

I was studying mainly primary mental abilities called associative memorizing and memorizing meaningful material. Results are shown in the table above. Correlation between the two tests which measure these abilities (Words in pairs and Memorizing a story) is 0.64, with tests of other primary mental abilities they correlate lower (between 0.20 and 0.44).

The broad retrieval factor :

The Wise sayings test gives us one result for ideational fluency and one result for originality of ideas. These two scores correlate 0.67. Correlations with other tests of primary mental abilities are lower (between 0.08 and 0.42). The research has also shown that fluency and originality of ideas are in slightly higher correlations with tests of nonverbal abilities (inductive reasoning, spatial ability, associative memorizing) than with tests of experiential abilities (verbal, numerical).

The broad factor of experiential abilities:

The tests Foreign words (verbal) and Calculations (numerical) correlate 0.52, their correlations with other tests of primary mental abilities are lower. The table below shows some of those correlations. We can see, that due to its speed nature the Calculations test correlates with other tests slightly higher than the Foreign words test.

The decline of abilities results in adult age

Below, the results, obtained with some primary mental abilities tests, are shown. Test were: Series (TN-20 and TN-10, reasoning), Patterns (P), Rotations (S), Digit span (Ms), Words in pairs (Ma), Calculations (N) and Foreign words (V). Results on tests of reasoning, memorizing, spatial ability and perceptual speed show progressive decline curves in adult age. The biggest decline is seen on perceptual speed. Verbal ability does not decline with age. It shows effects of constant experience accumulation. Somewhat special are results on the numeric test. In first decades of adulthood they show effects of experience accumulation, but after forties, due to the speed nature of numerical test and because of high demands on working memory, they start to decline progressively.