"While Kant’s work is written, in the main, from the epistemological standpoint, Reid remains true to the traditional British psychological method. The philosopher must undertake an examination of the operations of the mind. He is an anatomist of the mind."
Beattie, James; Ferguson, Adam; Reid, Thomas; Stewart, Dugald (2012-10-25). Selections from the Scottish Philosophy of Common Sense (p. 17). Veritatis Splendor Publications. Kindle Edition.
Beginning with Locke, it has been common for modern epistemology to study belief formation, a branch of psychology as noted above. This is distinct from the Cartesian project, and also from the Socratic project. It continues to be a popular approach by those who rely on Reid in contemporary philosophy of religion. This includes thinkers like Alvin Plantinga whose work on warranted belief takes an "externalist" or descriptive approach (third person) rather than the internalist or first person approach that asks "how do I (we) know?" This kind of epistemology also falls into the stream of ordinary or common person language and so the focus of its analysis of belief is almost always sense data. For religious philosophers like Plantinga this has included the sensus divinitatis which is a "sense" of the divine. William Alston argued that this sense has a place not unlike other senses, and Plantinga has compared it to the belief in other minds. In all such cases appearance (the deliverances of the senses) is taken as reality, and questions about how to get beyond appearance to reality are set aside. This would not satisfy either Descartes or Socrates, and it permits the idea that "knowledge" could be mistaken. The famous instance of this was given in examples by Gettier (see my post on the Gettier problem). These examples rely on the senses and testimony to support a knowledge claim even though neither of these can guarantee certainty (the distinction between true opinion and knowledge).
To describe Locke's project as psychology is helpful because it reminds us that he is attempting a descriptive work rather than a prescriptive work. In all such cases of description the question remains open: "how do we know this description, as opposed to another, is correct?" Alternative theories of belief formation have been offered since Locke's time. What stands out is that each has metaphysical presuppositions that must be true if the descriptive psychology is true: for Locke is was the immaterial self, God, and a theory of impressions, for Marx it was dialectic materialism, for Freud it was an evolutionary theory of the ego, id, and super-ego, for Skinner it was materialism with an emphasis on pain avoidance.
While psychology has its place, it is a different project from the Socratic project of distinguishing between the appearance and the reality of knowledge, and the Cartesian project of the search for certainty.