There has never been a better time to be a psychological scientist
In the history of psychology there have been three really major methodological developments.
The first was to realize that psychology could be thought of as a science (as opposed to a philosophical endeavour). The scientific method was relevant to the study of human behaviour and one could conduct experiments and expect replicable results.
The second was to understand that mathematics could be used to describe human behaviour. In fact the application of mathematics happened at about the same time as the introduction of the scientific method, as psychology sought to import the methods of physics.
The third was the introduction of brain imaging technologies to understand how the brain implements the mind.
I would argue that we are now in the midst of two new revolutions in methodology. In particular:
Wearable technologies and the Internet of Things provide us with ways of quantifying the environments in which individuals operate.
Social network data for the first time allows us to record the relationships and interactions between group members in situ.