Taking the extreme driving conditions as negative stimulus， the subjective feelings of 12 subjects as front-seat passenger were obtained in the process of real-vehicle testing by means of evaluation scale and interview， and the skin electrical activity data were recorded by the physical polygraph. On this basis， the change of the passengers’ subjective evaluation was studied by comparing the data before and after experiencing the unintended vehicle maneuver and using the hypothesis testing method. The results show that the negative stimulus improves the passengers’ expectation of vehicle control ability， but increases their anxiety about the uncertainty of vehicle decision-making intention. In addition， the combination of the data of skin conductance level and the data of the event during the test can reflect the change of passenger’s expectation.