All the previous research about unconscious thought has a problem, which is participants had no idea of the length of distraction time (they didn't know how long the time of unconscious thought was), thus they presented their results of unconscious thought under the condition of being controlled by their subjects. To solve this problem, we made some improvements on the previous research paradigm Dijksterhuis employed. Before engaging in unconscious thought, the participants were told the time the distraction task costs. Therefore, the participants can plan or control the emergence of the process and results of unconscious thought on their own. The experiment utilized a one-way between-participants design, with its independent variable being the time the participants were told before proceeding the distraction tasks and dependent variable being attitudinal difference score (the score of the most favorable roommate minus that of the worst one) One hundred and one undergraduate students (forty-two boys and fifty-nine girls) participated this study in exchange for credits. These participants were randomly assigned to four groups and completed a roommate decision task under one of the four experimental conditions: not knowing the time the distraction task costs (the same with Dijksterhuis,2004; Dijksterhuis & Nordgren, 2006)(which is called not knowing the time); being informed of a 3-minute distraction task and actually experienced a 3-minute one (informed 3 actually 3); being informed of a 5-minute distraction task but actually experienced a 3-minute one (informed 5 actually 3) and being told 3-minute distraction task but actually experienced a 5-minute one (informed 3 actually 5). 　　　The result showed a significant main effect for the four experimental conditions through variance analysis, F（3,97）=3.29，p<.05，η2=0.092. Multiple subsequent comparisons revealed that (1)the performance of the two groups “informed 3 actually 3” (M=19.69,SD=17.27) and “informed 3 actually 5”(M=17.84,SD=21.03) is better than the two groups “not knowing the time” (M= 8.80,SD=11.69) and “informed 5 actually 3” (M =8.72, SD =12.83) (p<.05); (2) the difference of performance between “informed 3 actually 3” and “informed 3 actually 5” is not significant (p＞.05); (3) the difference of performance between “not knowing the time” and “informed 5 actually 3” is also not significant (p＞.05). 　　The experiment results have demonstrated that individuals can plan or control the emergence of the results of unconscious thought on their own.