Yes, often they do. A linguist is also influenced by culture. For example the Canadian Inuit (Eskimo) have only one word for "snow" but the Inuit do not use compound words. If your first language is English you may choose to revert to English rather than go through a hundred Inuit words for the words relating to "snow" or any of its compound forms.

I've lived in Tokyo for 16 years now, and can speak Japanese fluently. I really felt like a milestone had been passed when I no longer formulated my sentences in English first, and another one when I began to dream in Japanese. So yes, when I speak English (my native language) I think entirely in English, and when I switch to Japanese, my thinking is also in Japanese. This is important to learning a language, more so (I think) than actually knowing many words) Being able to think naturally in the language you want to use. Learners or beginners usually think in their native languages.

As a multi-lingual person myself, I can tell you that I indeed think in different languages, depending upon context. Usually I think in my mother tongue, but especially when thinking about interactions with native speakers of another language (planning what I'm going to say, or thinking over a conversation from the past,) my subconscious dialogue occurs in the language of that other speaker. For example, I'm thinking about this question in English, because that's the language we're using, bimkom Ivrit, l'mashal (instead of Hebrew, for example. :) Also, when thinking about subjects which I've learned in my second (or third) language, I often think about them in the language in which I learned that subject, even though I can discuss the topic in my other languages.

More interestingly, as people learn new languages one of the better signs that the language is becoming internalized is when they start dreaming in the new language. As I learn a new language I look forward to those dreams in that language, because it shows me progressing to the deeper level of understanding in that tongue.

It was explained to me that language is only a pathway to express ideas. Like a village in a jungle. The more you use the path way, the more it is distinct. Stop using it and it may soon be overgrown by the jungle. In other words, we don't think in a language, we think ideas and express them in a language that we know.

I work with a man who is so fluent in several languages that when i asked him "What language do you primarily think in?" he had no answer. It depended on what he was doing at the time. You do, however, only think in one language at a time; I can say that as someone who speaks four languages fluently enough to lecture without notes in them.

I suppose not all people think the same way.

I'm not multi-lingual; English is my only language.

But I don't think primarily “in English”. English is a tool for communicating with others, and not for internal thought processes, which are usually more complex and more directly representative of that of which I am thinking than any combinations of English words I could put together to try to describe them.

For example, if I am thinking of putting on my shoes, I do not think of a string of words such as “I will pick up my shoes, put them on my feet, and tie the laces.” I think of the actions themselves, not of words to describe the actions.

Language isn't really relevant to my thoughts until I think of communicating them to others. I suppose that if I were multi-lingual, then what language I would think in, when I thought in a language, would be determined by what of my available languages I believed would be most readily understood by the person to whom I was thinking of communicating. If I'm not thinking of communicating, then language really isn't relevant.

I find myself pondering in English from time to time tbh (my first language is Danish). Usually when I'm imagining conversations with another person..

Yes we do. There was one point where I was speaking so much spanish I actually stopped thinking "in english" and all my thoughts were "in spanish". I found it quite interesting.

Yes. They dream in different languages too. Sometimes I dream in Spanish and Japanese.

My uncle lives in England (I'm Italian) and he's bilingual (Italian and English). He said he thinks like a machine, meaning that he doesn't think, for example, "I have to go to bed", he has the action himself in his brain, thinking no word in any language.