AO1 would be like what does the approach believe in, what are it's common research methods, any major case studies, etc.
For example:
The cognitive approach focuses on internal mental processes and has investigated many areas with this viewpoint such as memory, perception and thinking. They mainly use theoretical and computer models to explain these processes and heavily believe in the role of the schema. From this came the development of cognitive neuroscience that studies the influence of brain structure on mental processes, as seen in the discovery of the Broca's and Wernicke's area.