We studied visual-perceptual abilities of individuals with different levels of education (including adult illiterates) in Brazil (N = 136) and in Estonia (N = 560) with person-oriented methods of data analysis. Our aim was to discover whether dominant type of word meaning structure (WMS) can define the "Great Divide", the single breaking point that universally defines certain direction of subsequent to it cultural evolution. We particularly focused on the everyday concept-logical concept shift that takes place in the formal education system. We found that logical concepts were rarely available for illiterates; availability of logical conceptual thought increases together with the level of education. Most illiterates were able to find figures of concrete objects from complex overlapping and embedded contour figures but none of them could find all abstract figures from the same complex figures. Also none of the illiterates could perform beyond chance level in both mental rotation tasks together. Ability to perform correctly on all visual-spatial tasks increased with the increase in logical concepts and with the increasing level of education. The distribution of respondents according to the WMS level, level of education, and performance on the visual-spatial tasks indicated that individuals are developmentally heterogeneous: achievement of the tertiary level of education and logical conceptual thinking mechanisms does not guarantee high level performance on the visual-spatial tasks. The results are in agreement with the theory of unilineal hierarchic cultural evolution. Individual psychic development and cultural evolution can be both understood in terms of the WMS development.
Keywords: Great divide; Illiteracy; Level of education; Unilineal evolution; Visual perception; Word meaning structure.