number of errors within a definite time interval. However a partially valid hypothesis obviously has limitations and if the person insists to follow the hypothesis he/she would do more and more errors. The parts of the cycles where X˙ 0 , i.e. the number of errors grows, are shown as dashed lines.

Rethinking of failures may lead the person to that a new, closer to the truth, hypothesis is maturing, and the cyclic dynamics comes to the success when the person generates a hypothesis that happens to be completely valid and leads him/ her to the solution.

The notion that the thinking process in humans goes by a sort of oscillations appeared as early as late 19th century in the work "The principles of psychology" (1890) by one of the founders of the modern psychology William James. Observations of oscillation phenomena in many natural sciences suggest that it is an effect of time lagging that underlie every cyclic movement. In our case, the time lagging may be so that the person fails to generate a more valid hypothesis at the right time when the old one reaches its applicability limits. Langley and Rogers (2005) made a critical review of the classical theory of problem solving. In particular, it was noted that eager execution of partial plans can lead the problem solver into physical dead ends (Langley, Roger, 2005).

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