系列位置效应是一种心理偏误，指人们倾向于对首先见到的事物和最后见到的事物有更好的印象。分为首因效应和近因效应。

首因效应又称优先效应，是对“第一印象”或“先入为主”所产生的心理学现象，指在行为过程中，最先接触的事物会给人留下深刻的认知或感知，影响人对事物的感知和判断。

近因效应指在行为过程中，对事物的最近一次接触给人留下深刻的感知或认知，能对优先效应所形成的心理作用起到巩固、维持、否定、修改或调整等作用，在时间上与下一次购买决策最为接近，因此正或负的近因效应能促进或阻滞购买行为。

Serial position effect is the tendency of a person to recall the first and last items in a series best, and the middle items worst. The term was coined by Hermann Ebbinghaus through studies he performed on himself, and refers to the finding that recall accuracy varies as a function of an item's position within a study list. When asked to recall a list of items in any order (free recall), people tend to begin recall with the end of the list, recalling those items best (the recency effect). Among earlier list items, the first few items are recalled more frequently than the middle items (the primacy effect).