Beatty says there are different schools of thought to what the relationship betwwen the non-physical mind and the physical brain is. However, Monists believe that the mind and brain are the same thing. Psychology lies within the field of Science as nothing is proved in psychology. It is merely a collection of evidence which support particular theories. However, unlike in maths , these theories can be contradicted.
Psychology is however, different from other sciences.
Firstly as psychology deals with the mind it cannot be directly observed unlike other scientific processes. Some psychological experiments also differ from other sciences. For example, Roth carries on to say that research techniques depending on introspection techniques such as interviewing are hichly subjective, as although the subject may say they feel something you can't be sure if this is really the case. This also brings up the case of free will as in theory the participent can choose how to react to particular things. Therefore, as the subjects of study are supposedly unpredictable, repeated experiments under the same conditions may not produce the same results unlike in other sciences.