Читать книгу Social Psychology - Daniel W. Barrett - Страница 129

Before reading further, write down whether the Mississippi River is longer or shorter than 800 miles. How many miles long is it? Did you guess 775 or 900 or another number in the rough vicinity of 800? What if I were to instead ask if the Mississippi River is longer or shorter than 2100 miles, and then you were to estimate its length? Would you have given a different estimate? If you are like most of my social psychology students, then you would have guessed a much larger number after being asked the latter question. Why? The reason is that you assume that the number that I inserted into the question—either 800 or 2100—is relevant to the answer and reasonably close to the river’s actual length. You expect that the number was presented for a reason and therefore that you should use it as an informational guide for your answer (Chapman & Johnson, 2002; Morrow, 2002). You start with the given number—you anchor your estimate on it—and then adjust it either up or down (Tversky & Kahneman, 1974). The human tendency to rely on readily available information on which to base estimation and then to adjust that estimate up or down is another mental shortcut, called the anchoring and adjustment heuristic (Tversky & Kahneman, 1974). We use this heuristic in order to simplify the estimation process and conserve our mental resources. It often serves us well, providing a generally correct answer that can then be tweaked to produce an even better one. Interestingly, people adjust the anchor less if that anchor is more precise rather than rounded. For instance, participants in one study made smaller adjustments to the precise anchor of $4,998 versus the rounded anchor of $5,000 (see Research Box 3.1) (Janiszewski & Uy, 2008).

Why do we make this error? We do so because we assume that the information that we are provided is relevant to the answer requested (Chapman & Johnson, 2002). The assumption makes perfect sense—much of the time. Typically when we are faced with a problem or puzzle, whatever information is provided is relevant to the problem being solved. Again, this heuristic often works, but like availability and representativeness, it can sometimes lead us into error. A real-world illustration of anchoring and adjustment can be seen in the way that juries determine awards in liability cases based on whatever numbers are presented to them, regardless of the origin of or justification for those numbers (Chapman & Bornstein, 1996). This is the reason attorneys for the plaintiff often initially ask for unreasonable large dollar amounts in a legal settlement. Similar findings have been found with regard to the valuation of homes in real estate (Northcraft & Neale, 1987), estimating how long Gandhi lived (F. Strack & Mussweiler, 1997), and guessing the year in which George Washington was elected U.S. president (Epley & Gilovich, 2001).

Anchoring and Adjustment Heuristic: Mental shortcut in which people use readily available information on which to base estimation and then adjust that estimate up or down to arrive at a final judgment