Original sentence: However if the Flynn Effect is caused by intellectual stimulation, this may suggest that the Flynn Effect is unrelated to g because according to Jensen "the preponderance of evidence argues that variance in the level of g is not a psychologically manipulable variable, but rather a biological phenomenon under the control both of the genes and of those external physical variables that affect the physiological and biochemical functioning of the central nervous system, which mediates the behavioral manifestations of g".More recent studies have found that g has improved substantially
Edited sentence: More recent studies have found that g has improved substantially in direct contradiction of the Dickens and Flynn model which links the Flynn Effect to the cultural rather than the g component of IQ