Cc. Gonzalezvallejo et al., DO DECISION QUALITY AND PREFERENCE ORDER DEPEND ON WHETHER PROBABILITIES ARE VERBAL OR NUMERICAL, The American journal of psychology, 107(2), 1994, pp. 157-172
A surprising but common finding is that decision-making performance se
ems, on average, unaffected by whether decisions are based on probabil
ity phrases or on numerical probabilities. This study, however, shows
that on a trial-by-trial basis, preferences change as a function of ho
w gamble probabilities are represented. Decision makers rank ordered p
ositively valued gambles whose probabilities were another individual's
verbal or numerical chance estimates of specific events. Results show
ed that decision makers' rankings correlated more closely with payoffs
when probabilities were expressed verbally rather than numerically. T
his effect, in conjunction with the correlational structure of the gam
bles, resulted in differential earnings. under the two probability con
ditions. Verbal probabilities led to higher average expected profits w
hen gamble outcomes were more positively correlated with expected valu
e than were the gamble probabilities. The opposite was true for numeri
cal estimates.