The history of spoken and written language is a very interesting field of study. The manner in which languages evolve over time is similar, literally, to the way in which species evolve (languages do evolve much more rapidly than species). It is interesting to look at a kind of linguistic evolutionary tree, to see the parallels and differences alongside a genetic evolutionary tree, say of Indo-European languages in comparison to mitochondrial or Y-chromosome haplotype analysis in Eurasian groups.
Styles of language, and of word choice, etc. are certainly influenced by the culture of the day. It would be interesting to consider the degree to which word choices affect individual psychology. Some modern feminist thinking has certainly looked at the issue of language issues having important elements of psychological effects, particularly if the language itself is biased towards being sexist. This is a big area, one which I'd be interested to learn more about.
Another aspect of linguistics has to do with the multi-sensory nature of language perception. I find this very interesting, in expanding our understanding of the way the mind works in general: words on their own may be perceived or understood in different ways intellectually (this is an issue often discussed by literary scholars), but the manner in which words are perceived is also influenced very directly by core neurologic processes.
For example, I recently discovered the existence of a very powerful perceptual phenomenon called the "McGurk Effect." Here are a few examples from YouTube:
If you watch the video while listening to the speaker pronounce a syllable, it sounds completely different from when you close your eyes and just listen without watching. The phenomenon demonstrates how powerfully visual input changes how we perceive an auditory stimulus. I was surprised to find how overpoweringly strong the effect was, how difficult it is to somehow "over-ride" it.
Other linguistics research demonstrates that other sensory modalities, including tactile, also have strong effects on language perception.
As an extension to psychiatry, and to the general workings of the mind, I think it is true that many different perceptual and psychological inputs have very strong effects on the way we perceive other stimuli. In social exchanges, there may be a wide variety of inputs which we are not consciously aware of, which could be substantially affecting our experiences. In most cases, these other inputs assist us in understanding better. The purpose of having one sensory modality influence another is to bolster the input from both, so as to facilitate understanding. This is the foundation for how lip-reading works, for example. But if one input is, without our knowledge, giving opposing information compared to another input, then this could lead to a very problematic behavioural cycle.
I think such phenomena are likely to happen in many anxiety disorders, for example, in which the anticipatory anxiety, and resultant physical and emotional tension, are likely to cause one's perceptions of benign social stimuli to become exaggeratedly negative. This is happening not just on an intellectual level, but arguably on a core perceptual level, akin to the McGurk effect. Similar perceptual distortions are likely to happen in other psychological states, such as depression. The cognitive theory of depression centres around so-called "cognitive distortions," but I think it is important to expand this concept to admit that the phenomena could be powerful "cognitive-perceptual" distortions, which could require a lot of disciplined work to overcome. Without acknowledging the strength of this phenomenon, frustration could quickly set in, just as it would if you were to simply practice hearing McGurk-style syllables without knowledge of the McGurk effect.