Capacity and retention capability of working memory modify the strength of the RT/IQ correlation: a short note

The limited capacity theory assumes that working memory (WM) has limited capacity to process information and, at the same time, to store other pieces of information, necessary for further processing. Quick processing of data is supposed to be the only way to solve the task without the risk of losing vital pieces of information. We predicted, then, that the correlation between mental speed, measured by reaction time (RT), and the intelligence quotient (IQ) should not appear in the case of persons who possess a relatively capacious WM store, or who show increased retention capability of their WM store. Such persons do not need to be fast, whereas, for people who show poorer indices of capacity or retention capability of WM, mental speed is the only way to tackle a complex and difficult intellectual task. As predicted, the RT/IQ correlation appeared much stronger in the group of subjects characterized by lower retention capability and capacity of WM.