IQ and Retention:

>... When persons are equated in degree of original learning of simple material, their retention measured at a later time is only slightly if at all correlated with IQ. The retention of more complex learning, however, involves meaningfulness and the way in which the learner has transformed or encoded the material. This is related to the degree of the learner’s under­standing, the extent to which the learned material is linked into the learner’s preexisting associative and conceptual network, and the learner’s capacity for conceptual reconstruc­tion of the whole material from a few recollected principles. The more that these aspects of memory can play a part in the material to be learned and later recalled, the more that retention measures are correlated with IQ.<

Arthur R. Jensen

Bias in Mental Testing - p. 329 (1980)

[See also: The myth of “they weren’t ever taught….”]