Introduction: Although the relationship between reaction time and Intelligence quotient (IQ) scores involves an important part of theoretical information processing approaches towards individual differences, data obtained in this area are sparse or even non- congruent. Those who do not believe the relationship between reaction time and intelligence, often argue that the reaction time is too simple, banal and non-intelligent and thus, it cannot reflect a variable with the same sophistication, elegance and ambiguity of intelligence. In contrast, some believe that the reaction time is indicative of fluid intelligence has a growing trend until youth time (crescendo) and then steadily decreases (decrescendo). New researchers also believe that to judge the relationship between intelligence and reaction time, the difference between processing time and reaction time should be considered.
Method & Results: The present study, comparing recorded results of present studies and reviewing stated theories, seeks to answer this question "what is the relationship between reaction time and intelligence and whether reaction time can predict the differences in the intelligent structure?"
Conclusion: The relationship between reaction time and IQ is too complicated and revealing a significant correlation depends on various variables (e.g. methodology, data analysis, instrument etc.).