Suppose a subject completes a signal detection experiment and achieves a hit rate of 50%. Dissatisfied with his level of performance, he decides to change his strategy. He repeats the experiment and this time achieves a hit rate of 90%. Does this mean that the subject has improved his discrimination performance according to signal detection theory?
A. We can't tell anything from the information given
B. No, unless the false alarm rate decreased as well.
C. Yes, by 40%
D. Yes, by less than 40%