Faces provide two different types of information which help the perceptions and judgments of people. The first type of information is stable across changes in appearance, which is the identity of a person. Faces provide cues for judgments of stable characteristics and thus identification of a person even though their expression changes or seeing them from different viewpoints. Webster and colleagues (2004) indicated that face perception is a fundamental process for determining the features of others, such as age, gender, and ethnicity. Thus, faces serve as a crucial cue for people to identify different people and interact with them. The second type of information provides cues for judgments of characteristics that vary over time, such as emotion and facial expression. People can make inferences about others traits and underlying characteristics from their facial features and emotion shown (Olivola & Todorov, 200; Todorov et al., 2005; Webster et al., 2004).
Many studies have suggested that people draw trait inferences from the facial appearance of others quickly and spontan
eously (Bar, Neta, & Linz, 2006; Rhodes et al., 205; Todorov, Pakrashi, & Oosterhof, 2009). For example, Bar and colleagues (2006) suggested that trait inferences could be drawn rapidly within the first 39 milliseconds based on the available information shown on the faces. Also, Todorov and colleagues (2009) demonstrated that 33 milliseconds of exposure to faces is enough for people to draw a specific trait inference and make a snap judgment from a strangers face. Thus, it is believed that people can extract important facial features effectively and draw inferences from an unknown face within a short period of time. However, it is suggested that the automatically formed inferences leave little room for conscious judgmental processes to occur or change the already made inferences (Kahneman, 2003). According to Willis and Todorov (2006), there was a large correlation between the trait judgments made after 00 milliseconds of exposures of faces and those made when time constraints were absent. Therefore, people hardly change their impressions towards others once they are formed.