PPIK, for intelligence-as-Process,Personality,Interests, and intelligence as
Knowledge. Some basic attributes of the theory are similar to those offered by
Cattell (1957), in that there is much shared conceptualization regarding proc-
ess-type abilities (e.g., Gf ) and the development of knowledge (e.g., Gc). In
Cattell’s investment hypothesis, Gc grows out of the investments of Gf. Other
influences, such as personality, interests, and so on affect both intellectual de-
velopment and other domains (such as scholastic achievement)—for details see
Cattell (1971/1987). There are also salient differences between Cattell’s ap-
proach and the PPIK approach. Domain knowledge is contained within
Cattell’s original depiction of Gc, but as noted by Cattell, was seen as impracti-
cal for assessment, because one might need a test for every identifiable area of
knowledge. Instead, most Gc assessments focus on knowledge that is common
to a dominant culture, or they focus on verbal knowledge and skills (such as
reading comprehension and general vocabulary). In contrast, the criteria of in-
terest for the PPIK approach are the breadth and depth of content, or domain
knowledge, for two important reasons: The first reason is that there is extant
justification that for most intents and purposes, adult intellectual effectiveness,
in terms of what tasks an individual can perform, is determined more by what
the individual knows and less by the individual’s ability to perform context-
independent working memory or abstract reasoning tasks. The second reason
is that, rather than approaching the question of commonality among cogni-
tion, affect, and conation by only looking at laboratory tasks that have little in
the way of real-world relevance, the question of commonality might best be ap-
proached by looking for communalities where they are most likely to be
found—that is, in terms of what the individual brings with him or her to the as-
sessment situation.
The PPIK approach gains a substantial degree of Brunswik Symmetry be-
tween predictors and criteria, and at the same time, it takes the investigation
of adult intellectual development beyond analysis of obscure laboratory tasks
that only tend to show that middle-aged and older adults are less able learn-
ers of trivial tasks, when compared to younger adults. One key hypothesis for
the PPIK approach is that, when one considers that middle-aged and older
adults are likely to have much higher levels of investment in acquisition and
maintenance of domain knowledge than do younger adults, it is likely that
the average middle-aged adult is quite a bit more knowledgeable than the
average 18-year-old. Given the notion that knowledge is a more important
determinant of intellectual performance (e.g., see Hunter, 1983), the PPIK
approach suggests that inclusion of domain knowledge, along with intelli-
gence-as-process and traditional measures of Gc, might yield an evaluation
that shows that, on average, middle-aged adults have higher overall intelli-
gence than younger adults. Such an orientation is consistent with the specula-
tions of many investigators over the past 70 or so years (e.g., see Miles, 1934),
but is inconsistent with the traditional IQ org-centered approach that sug-
- TYPICAL AND MAXIMAL PERFORMANCE 127