Abstract
According to the paradigm of Computers Are Social Actors (CASA), an interface can be designed to represent the personality of a computer. Users can distinguish the personalities of the computer interfaces, and tend to treat computers like human beings. The present study applied the CASA paradigm to design a web interface by manipulating the visual elements. This is an experimental study. The independent variables are introversion and extroversion of the subjects and interfaces. The dependent variables include degree of compliance of the scale results, scale accuracy, willingness to re-attend the test, perceived introversion and extroversion of the interfaces, degree of fondness with the interfaces, and experience of interaction. The researchers designed introverted and extroverted interfaces by manipulating visual elements. In order to measure the feelings of the subjects, this research used a new method-the Barnum Effect. Eighty-seven introverted and extroverted subjects participated in this study to interact with introverted and extroverted interfaces. After completing a fake scale, the subjects received favorable, neutral and unfavorable statements on the screen and then filled in the questionnaires. ANOVA was used as the statistical method to analyze the data. The results show that the Barnum Effect does exist in Human-Computer Interaction. Manipulating visual elements can successfully represent the personality of interfaces. It is safer to use introverted interfaces to deliver messages to either extrovert or introvert users, no matter what kind of statements are used. When the conveyed information is positive, designers should apply the similarity-attraction theory in design; when the information is negative, designers can apply the complementarity theory to ensure the credibility to users.