Abstract: Anchoring effect–the assimilation of a numeric estimate to a previously provided standard–is typically described as robust and persistent, which affects human’s decision under uncertainty. Basic anchoring effect was caused by a simple number. The researches of anchoring effect will help us understand the negative impact of this heuristic in decision making and explore effective ways to reduce the bias. There have been numerous researches on anchoring effect, however, the precondition of anchoring effect, whether basic anchoring effect exist and the mechanism of it were not clear to this day and there has been considerable controversy. In order to investigate these problems, we conducted two experiments. In the first experiment, we exploited a mixed design to explore whether attention to the anchor was the precondition of anchoring effect, with anchor levels (high, low, non) as within-subject variable and presentation time (15ms, 45ms, 75ms, 1000ms) as between-subject variable. We recruited 120 college students to participate our experiment, there were 45 boys and 75 girls. The results showed that in 15ms condition, there was not anchoring effect, whereas in 75ms and 1000ms conditions, both observed anchoring effect, which demonstrated that attention to the anchor not comparison was very important to anchoring effect. In addition, in 45ms condition, participants were aware of low anchors but not high anchors, and we observed anchoring effect only in the low anchor condition. In sum, whether the anchor was high or low, anchoring effect was observed only if participants were awareness to the anchor. Therefore, attention to the anchor is the precondition of anchoring effect. What’s more, results also confirmed that basic anchoring effect was not fragile as previous researches indicated. With increased time to pay attention to anchors, the anchoring effect grew larger, which provided initial evidence supported Numeric Priming Account. The second study started from the conflict of the Selective Accessibility Account and the Numeric Priming Account, we set pairs of anchors which had identical semantic meaning but different presentations, such as 5 kilograms and 5000 grams. According to the Selective Accessibility Account, both anchors were semantically resemble, so there would be the same anchoring effect; whereas according to the Numeric Priming Account, anchoring effect was dependent on the absolute number of anchor, so 5 kilograms would lead to lower estimation and 5000 grams would lead to higher estimation. Results of 20 students showed that high and low anchors lead to different anchoring effect, which supported the Numeric Priming Account. In sum, this research shed light on the precondition of anchoring effect and provide evidence to the mechanism controversy of basic anchoring effect. Only when participants are aware of anchors, there would be anchoring effect, and the magnitude of it rely on the degree of attention to the anchors. In terms of explaining the basic anchoring effect, the Numeric Priming Account is more suitable. More studies were needed such as the development of anchoring effect in life span, which will enable us to understand this effect deeply and thoroughly.

Key words: anchoring effect, basic anchoring effect, Selective Accessibility Account, Numeric Priming Account