We measured the personality type of the students in a large introductory physics course of mostly life science students using the True Colors instrument. We found large correlations of personality type with performance on the precourse Force Concept Inventory (FCI), both term tests, the postcourse FCI, and the final examination. We also saw correlations with the normalized gain on the FCI. The personality profile of the students in this course is very different from the profile of the physics faculty and graduate students, and also very different from the profile of students taking the introductory physics course intended for physics majors and specialists.