Problem Statement: In recent years many different studies have examined critical thinking disposition; however, these studies focus on investigating the variables that are related to this subject. There are actually few empirical studies in the literature. It is clear that there is a need for experimental research in order to comprehend the process of critical thinking in-depth.
Purpose of the Study: This study investigates the contrastive effect of an experimental program and the placebo effect on the improvement of critical thinking disposition of university students.
Method: Sixty-three participants from the students of Arabic Language Education in the Faculty of Education in Adiyaman University were divided into three classes as experiment, placebo, and control groups, each of which consisted of 21 participants. As the placement was on an already existing class system, the study was conducted using a quasi-experimental design. In the experiment group, an eight-week program, which was developed by researchers, was applied. The study was carried out in the last 10 to 15 minutes of Educational Psychology lessons. In the placebo group a positive atmosphere was provided in the class and the students were motivated toward critical thinking by being informed about the necessities of it, and in the control group no applications were used. California Critical Thinking Disposition Inventory, which was adapted into Turkish by Kokdemir in 2003, was used to assess the critical thinking skills of the participants. SPSS 20.0 was used to analyze data. Variance analysis, independent samples t-test and Ancova analysis were used to examine the data.
Findings and Results: Independent samples t-test results pointed out that there was not a significant difference between male and female participants. Variance analysis conducted for age variables produced no significant difference between the groups. It was found that the highest improvement in critical thinking disposition of teacher candidates was observed in the placebo group, and the experimental group ranked second; however, Ancova analysis showed that there were no significant differences between the experiment, the placebo and the control groups‘ posttests.
Conclusion and Recommendations: Age, gender, and groups of the student were observed as not being significant variables in critical thinking disposition at the end of the study. Within the study, it is an important finding that merely the effort for creating a positive atmosphere in the placebo group induces a better level of improvement than the experiment group where activity and practice were made possible. Findings were discussed based on the relevant literature.
Keywords: Thinking, critical thinking, placebo effect, teacher candidates