Some readers of this book might want to develop VR systems or experiences. In this case, pay close attention to this next point! When a scientist designs an experiment for an organism, as shown in Figure 1.2, then the separation is clear: The laboratory subject (organism) has a first-person experience, while the scientist is a third-person observer. The scientist carefully designs the VR system as part of an experiment that will help to resolve a scientific hypothesis. For example, how does turning off a few neurons in a rat's brain affect its navigation ability? On the other hand, when engineers or developers construct a VR system or experience, they are usually targeting themselves and people like them. They feel perfectly comfortable moving back and forth between being the ``scientist'' and the ``lab subject'' while evaluating and refining their work. As you will learn throughout this book, this is a bad idea! The creators of the experience are heavily biased by their desire for it to succeed without having to redo their work. They also know what the experience is supposed to mean or accomplish, which provides a strong bias in comparison to a fresh subject. To complicate matters further, the creator's body will physically and mentally adapt to whatever flaws are present so that they may soon become invisible. You have probably seen these kinds of things before. For example, it is hard to predict how others will react to your own writing. Also, it is usually harder to proofread your own writing in comparison to that of others. In the case of VR, these effects are much stronger and yet elusive to the point that you must force yourself to pay attention to them. Take great care when hijacking the senses that you have trusted all of your life. This will most likely be uncharted territory for you.
Steven M LaValle 2019-03-14