Researchers have investigated numerous possible risk factors. They've looked at psychologic problems, distress levels, and cognitive level of function as possibilities. Studies have been done looking for a link between personality traits, anxiety, history of emotional problems and whiplash disorders.
There may be some defining or prognostic factors. But the studies that have been done were not well designed. Results of low quality research are not reliable enough to use as evidence.
Some studies of chronic low back pain have found that beliefs about pain and fear of pain can result in a reaction called fear avoidance. Fear avoidance is the belief that certain movements or activities should be avoided to prevent pain or re-injury from occurring.
It's possible that people who develop chronic whiplash start out with fear avoidance behaviors. Best practice suggests keeping active during the recovery process. It may be helpful to get out together and go for a walk everyday for the next week. The activity may provide a distraction and the movement may help in the healing process.