|
208
F R E D E R I C K E T A L .
“g” factor. Typically, a posited psychological construct (or “trait”) is considered
useful only if it satisfies three criteria: it remains relatively constant across time
within a particular individual; it predicts behavior across a wide range of situa-
tions, and different measures of it correlate highly with one another. The concept
of intelligence satisfies these criteria fairly well.
43
First, performance in tests of
cognitive ability at early ages correlates highly with performance on such tests at
all subsequent ages. Second, cognitive ability (as measured by such tests) predicts
a wide range of important life outcomes, such as criminal behavior and income.
Third, abilities that we regard as expressions of intelligence correlate strongly
with each other. Indeed, when discussing the construction of intelligence tests,
Herrnstein and Murray (1994, 3) note, “It turned out to be nearly impossible to
devise items that plausibly measured some cognitive skill and were
not
positively
correlated with other items that plausibly measured some cognitive skill.”
The posited construct of time preference does not fare as well by these criteria.
First, no longitudinal studies have been conducted to permit any conclusions
about the temporal stability of time preference.
44
Second, correlations between
various measures of time preference or between measures of time preference and
plausible real-world expressions of it are modest, at best. Chapman and Elstein
(1995) and Chapman, Nelson, and Hier (1999) found only weak correlations be-
tween discount rates for money and for health, and Chapman and Elstein found
almost no correlation between discount rates for losses and for gains. Fuchs
(1982) found no correlation between a prototypical measure of time preference
(for example, “Would you choose $1,500 now or $4,000 in five years?”) and other
behaviors that would plausibly be affected by time preference (for example,
smoking, credit card debt, seat belt use, and the frequency of exercise and dental
checkups). Nor did he find much correlation among any of these reported behav-
iors (see also Nyhus 1995).
45
Chapman and Coups (1999) found that corporate
employees who chose to receive an influenza vaccination did have significantly
lower discount rates (as inferred from a matching task with monetary losses), but
43
Debates remain, however, about whether traditional measures exclude important dimensions, and
whether a multidimensional account of intelligence would have even greater explanatory power.
Sternberg (1985), for example, argues that intelligence is usefully decomposed into three dimensions:
analytical intelligence, which includes the ability to identify problems, compute strategies, and moni-
tor solutions, and is measured well by existing IQ tests; creative intelligence, which reflects the ability
to generate problem-solving options, and practical intelligence, which involves the ability to imple-
ment problem-solving options.
44
Although there have been no longitudinal studies of time preference per se, Mischel and his col-
leagues did find that a child’s capacity to delay gratification was significantly correlated with
other
variables assessed decades later, including academic achievement and self-esteem (Ayduk et al. 2000;
Mischel, Shoda, and Peake 1988; Shoda, Mischel, and Peake 1990). Of course, this provides evidence
for construct validity only to the extent that one views these other variables as expressions of time
preference. We also note that while there is little evidence that intertemporal behaviors are stable over
long periods, there is some evidence that time preference is not strictly constant over time for all peo-
ple. Heroin addicts discount both drugs and money more steeply when they are craving heroin than
when they are not (Giordano et al. 2001).
45
A similar lack of
intraindividual
consistency has been observed in risk taking (MacCrimmon and
Wehrung 1990).
Do'stlaringiz bilan baham: |
