When people talk to each other, assumptions are made about their common knowledge. So depending on who you are and who you are talking to you are going to use different words in different ways. It might be the case that the colloquial form of a language actually reveals a lot about the culture that gave birth to it that the written form doesn't. Maybe the writing makes sense on a superficial level, (the colour green, etc) but actually has a lot of subtext that only becomes clear when someone from the same background as the writer reads it. You can get away with deducing a lot of this from other pieces of writing, but what about culture that don't heavily rely on writing for communication? Or learning about parts of society that didn't write much?

I like that you brought up color. Many people have wondered, "do I see the same blue that my friend sees?" It's hard to say, from a physiological perspective as well as from a language perspective. French and English are very close with a long history of interchange, but even so the associations a native English speaker has with the word "green" are different from the associations a native French speaker has with "vert" and certainly this is true of a native English speaker speaking French and vice versa.

Another way that language can be influential on how people think about things is pronouns. In English we use, "I, he, she, it, etc." I use the Southern Vietnamese dialect as an example as it's very different from English and I have experience with it. In Vietnamese, there is no 100% equivalent of "I" nor even "he," "she" or "it." The closest that Vietnamese has to "I" is "*tôi,*" which is typically only used in formal situations or interactions where one is unfamiliar with the people spoken to. The casual way of referring to oneself depends on gender and rank and or age. For a man among friends or family, the pronoun used to refer to oneself as "anh". However, the pronoun for another male of the same rank is also "anh". In a formal setting one might refer to another man as "*chú*" or "father's younger brother" as a rough equivalent of "mister". For a female there is a similar set of pronouns which go from "grandmother" to "aunt" to "sister" to "person of lower rank" and for a child of either gender a pronoun that can be interpreted in English merely as "child" or even "it" or "thing."

These are not minor differences. They actively shape a person's idea of identity and their place and position within their society. As you can see, the pronouns tend to have familial connotations. This is not to imply that Vietnamese don't have the same ideas as English speakers, or that they are incapable of seeing the world the way an English speaker does, but it does mean that their default lens used to look at and interpret the world around them and their relationship to it is different. I also don't mean to imply that due to language Vietnamese people treat people badly. However, it can be jarring for an outsider to experience.

Many expatriates in Vietnam get annoyed by the seemingly scripted introductory conversations when interacting with Vietnamese people. They tend to go along this line of questioning.

"What's your name? Where are you from? How old are you? What's your job?" And less so than in the past, but still commonly, "How much money do you make?" These questions are asked to determine status and what pronoun to use and how much respect to afford the person. This is not entirely alien to English speakers, but they way that they'll go about it is very different.

I'm not sure what others have meant when they've said to you that they think that language influences perceptions, but I really mean that your language can have an effect on how you see the world and often it's not in hugely obvious ways. Even if we look at children as they learn words, we can see the difference in how they see things as their vocabulary grows. At first things are "good" or "bad." Later, "not good" which is like "bad" but not to the same degree. Then there's "not bad" which can mean, "it's not as good as it could be" or depending on the tone, "this is good, but I'm not going to say that it is."

So, when you take all the color and shading particular to a language along with its quirks of grammar and vocabulary, then language has a very subtle but powerful way of influencing our perceptions. Some even go so far as to label it as the first layer of technology in the human experience.