The introduction of occupant position sensors into automobiles raises questions about the response of these sensors to current crash test dummies. To adequately test the performance of these sensors in a crash environment, it is crucial that crash test dummies resemble humans. Each sensor technology perceives the crash test dummy as being different from a human. These differences range considerably. The differences for four sensor technologies, capacitive, electric field, ultrasonic and pressure pattern, are described. The differences between humans and crash test dummies are discussed, along with possible modifications to the crash test dummies that improve the biofidelity of the crash test dummy. Results will be presented from testing on a mid-sized male and small female.