He examined the methods used in these studies and critically evaluated them and also mentioned their limitations according to his assessment.
The author has not clearly discussed the significance of his results but he has thoroughly mentioned the results from previous studies and their positive and negatives have been identified too. He shows why some results cannot be trusted and why some were optimistic but are not relevant his particular hypothesis. For example in one study he found that though the results were optimistic, they are not relevant because the researchers had focused on immediate effects on mental exercise instead of its long-term benefits. In other words, the author agrees that there is a significant difference in mental performance immediately after a mentally stimulating exercise but he doesn't agree that the benefits would last a life time or for longer duration of time.
The sections on previous studies are adequately scientific with data presented carefully with the help of graphs. However author has refrained from using very complex language or methods for examining previous studies.
The article concludes that there is no significant...
I do agree that author has done a good job of evaluating previous studies and their limitations, but I do not agree with his conclusion. The article is widely cited which shows that many experts trust the results or find the article useful in their studies but due to the lack of a scientific method for comparison, examination and evaluation of studies, it is difficult to disregard the results found by others and agree with author's conclusion. His conclusion is mostly a matter of opinion and for that reason; I do not think it can be assigned much weight. I have also observed that people who have led a very active life in pursuance of mental activities generally age much slower mentally. Their cognition level remains very high compared to in-active individuals and they tend to speak more clearly, understand others better and if other health issues are not a problem, they are generally very agile mentally and demonstrate better mental faculties.
REFERENCE
Salthouse TA. Mental exercise and mental aging. Perspectives on Psychological Science 2007;1:68-86.
