This is an interesting topic, but this article seems to merge a series of disparate elements.

For instance, the Gestalt Principles that you refer, have also been accurately described in the article by Norbert Gaal — https://blog.intellyo.com/content-marketing/ux-and-psychology-go-hand-in-hand-how-gestalt-theory-appears-in-ux-design.

The article from Miklos Philips on this topic is also impeccable, since it also highlights a far more scientific and research driven approach to psychology in UX Design. https://www.toptal.com/designers/ux/design-psychology-neuroscience-of-ux

Other interesting articles and products that detail how psychology is applicable to UX design include: https://digitalpsychology.io/ and also of course The Laws of UX — https://lawsofux.com/