Do memories exist when we are not having them?
We have no definite location in the brain for the storage of memories. The best hypothesis we have at the moment is that memories activate large swathes of brain areas, but there is no one storage area. Thus, some have argued that memories are only held in the neuronal firing patterns that recreate them. So, if we only access memories while the appropriate neurons are firing, do those memories exist when we are not experiencing them? I would argue no, in that sense.
What is the relationship between Type I and Type II error?
Type I error is the chance to make a false-positive error, while Type II error is the chance to make a false-negative error. Generally, Type I is considered to be much more worrisome, as a false-positive across numerous disciplines could lead to serious consequences. The issue, though, is that both types of errors are in balance; increasing one decreases the other, and vice-versa. Thus, when designing studies, you must carefully consider the necessary aspects of the design to ensure you have sufficient power to find an effect while avoiding the potential for a false-positive finding.
What is the nature of cognitive science as a discipline compared to general psychology?
Psychology is the study of behavior using behavioral and cognitive measures. Cognitive science, on the other hand, also studies behavior but it utilizes a more interdisciplinary toolbox. Basically, the two disciplines are equipped to answer different questions, or the same questions but in different ways.