Based on the continuum model of impression formation (Fiske & Neuberg, 1990), information processing can be more or less automated or controlled and thus relies more or less on stereotype-based or individual-based characteristics. Also, teachers' impression formation can be influenced by social categories like students' ethnic background or social status. However, when teachers form an impression of students' abilities or performance social categories should not play a role. But a lot of empirical findings show that teachers make a difference depending on students' backgrounds. Whether this can be explained by a more automated or controlled information processing depending on students' backgrounds is still an open question. Accordingly, the purpose of this study was to investigate teacher students' impression formation in dependence on students' ethnic backgrounds and social status. In order to investigate whether information processing differs according to students' ethnic backgrounds and social status, an experimental eye-tracking study with 45 teacher students was designed. As physiological processes are strongly connected to psychological processes, specific eye-movements can be interpreted as indicators for physiological arousal in first place, but might also allow conclusions about mental processes like information processing. Pupil diameter and blink rate were measured while participants read three case vignettes with manipulated student background. Analysis of variance with repeated measures showed differences in pupil diameter and blink rate according to students' background. Results showed less arousal when forming an impression about students without immigrant background and with high social status compared to students with immigrant background and with low social status. This might indicate more automated information processing for non-immigrant students with high-status, and more controlled processing for students with immigrant background and low-status.