Peter Gordon, a psychologist from Columbia University, highlights eight experiments involving seven Pirahã speakers. Six of the experiments were all related in that the speakers were instructed to match groups of items to the correct number displayed elsewhere. The other two experiments had them recall how many items had been placed into a container, and lastly differentiate between various containers by the number of symbols that were pictured on the outside. Gordon found that the speakers of Pirahã could distinguish between the numbers one, two, and three relatively accurately, but any quantity larger than that was essentially indistinguishable to them. He also observed that the more the amount represented by the number increased, the poorer the subjects performed. Gordon concluded, in direct contrast to Deutscher, that speakers of Pirahã are restricted to thinking about numbers through symbols or other representations. These speakers think of items  as small, larger, or many. The speakers did not demonstrate an ability to learn numbers; after being taught in the Portuguese language for eight months, not one individual could count to ten.

Michael Frank  ran further experiments on the Pirahã published in "Numbers as a cognitive technology," and found that Everett was wrong, the Pirahã did not have words for "one," or "two," but instead had words for "small," "somewhat larger," and "many."

For example, one may perceive different colors even while missing a particular word for each shade, like New Guinea aborigines can distinguish between the colors green and blue even though they have only one word to describe both colors. In communities where language does not exist to describe color, it does not mean the concept is void – rather the community may have a description or unique phrase to determine the concept. Everett describes his research into the Pirahã tribe who use language to describe color concepts in a different way to English speakers: “[…] each word for color in Pirahã was actually a phrase. For example, biísai did not mean simply ‘red’. It was a phrase that meant ‘it is like blood’.”"

In the course of his research, Whorf noticed that Hopi and some other languages  were built upon a different structure than that of English and many other languages. He discovered several significant features distinguishing  Hopi which he used to continue formulating his concept of  linguistic determinism.

For example, Hopi is a ‘timeless’ language, whose verbal system lacks tenses. The assessment of time is different from the linear temporal view of past, present, and future because it indicates the event’s time duration. Whorf observed that sense of time varies with each observer:

Hopi time is non-dimensional and cannot be counted or measured in typical  language measurement , i.e. the Hopi will not say “I stayed six days,” but “I left on the sixth day.” In the Hopi  perception of time, it is crucial to determine whether an event can be warranted to have occurred, to be occurring, or to be expected to occur. Hopi grammatical categories signify view of the world as an ongoing process, where time is not divided into fixed segments so that certain things recur, e.g. minutes, evenings, or days. The linguistic structure of some other languages, on the other hand, gives its speakers a more fixed, objectified and measurable understanding of time and space, where they distinguish between countable and uncountable objects and view time as a linear sequence of past, present, and future.

The Hopi language also contains a verb system which can make a single-action verb into a repeated/prolonged action verb with an extension of the word. For example, “tíri” translates to “he gives a start” but “tirírita” becomes “he is trembling”. Other languages translate the meaning of these verbs differently so, in support of linguistic determinism, Whorf might have used this to argue that the Hopi and other speakers think about these verbs differently, thus their language is shaped by their thoughts.

Whorf argues that since thought is expressed and transmitted through language, it follows that a differently structured language must shape thought along its lines, thus influencing perception. Consequently, a Hopi speaker who perceives the world through the medium of his language must see reality through the patterns laid down by its linguistic structure.

An outspoken critic of linguistic determinism, cognitive psychologist Steven Pinker, known for his alignment with Chomsky's universalist ideas, disagrees strongly with Whorf’s analysis. Pinker argued that Whorf relied too heavily on linguistic data alone to draw conclusions regarding the relationship between language and thought. In his book, The Language Instinct, Pinker dismisses linguistic determinism as a "conventional absurdity," instead proposing a universal language of thought - termed Mentalese.

He asserts that Whorf was completely mistaken in his characterization of the Hopi as having no concept of time and that the Hopi do in fact have tense, units of time, temporal metaphors, and a complex system of time-keeping."

Deutscher introduces the Guugu Ymithirr language, where they describe everything geocentrically based on its cardinal direction (the chair is to the East) rather than egocentrically (the chair is to your right). It is clear how this system of expressing position and location influenced the Guugu Ymithirr's conceptualization of space. Their description of objects' locations, within photos or on television, would change based on the rotation of the media because they described things using cardinal directions. For example, if there was a photograph with a tree on the left side of the photo and a girl on the right side, the speakers of Guugu Yimithirr would describe the tree as West of the girl. If the photo was then rotated 90 degrees clockwise the tree would now be described as North of the girl.

The implications, as Deutscher describes, were that the speakers of Guugu Yimithirr have a "perfect pitch" for direction and that their sense of direction is completely non-egocentric. In one experiment, speakers were asked to recall a very recent event and describe it. The people recalled their placement, as well as the placement of important people and objects around them perfectly, even accounting for their position in the retelling. Many years later, the same people were asked to recall that same event, and it was shown that over time, they were still able to accurately recall the directionality of objects and people. Deutscher argues that this example illustrates that geocentric direction is encoded into the memories of Guugu Ymithirr because their language requires it. More broadly, they see the world differently due to their unique conceptualization of space, but this does not mean that they are trapped within the constraints of their language.

In an interview about his work, Deutscher condemned the Whorf’s strong concept of linguistic relativism because there is no evidence that language can truly restrict the ability to reason or to gain knowledge. Even if languages do not provide “ready made labels” for certain concepts or objects, most people are still able to understand and discuss these ideas."

Other studies supporting the principle of linguistic determinism have shown that people find it easier to recognize and remember shades of colors for which they have a specific name. For example, there are two words in Russian for different shades of blue, and Russian-speakers are faster at discriminating between the shades than are English-speakers.

Pinker criticizes this argument for linguistic determinism as well. He points out that although a plethora of languages label colors differently, this variation in language cannot change the human biological process of color perception; he also notes that there are universal tendencies in the color labels that languages possess (i.e. if a language has two terms, they will be for white and black; with three terms, add red; with four, add either yellow or green).

Pinker concludes that linguistic determinism derives from the tendency to equate thought with language, but evidence from cognitive science now illustrates that thought precedes language. In his eyes, humans think not in individual languages, but in a shared language of thought. In turn, knowledge of a particular language constitutes the ability to translate this Mentalese into a string of words for the sake of communication."