According to Vygotsky, cognitive development does not follow predetermined stages but occurs in reaction to various sociocultural contexts. For example, a child carried on their mother’s back is exposed to more learning opportunities than a child in a crib (Steiner and Mahn, 2012). Observing social phenomena allows children to develop mental representations, gradually internalizing social aspects into their understanding. In education, teachers facilitate this by exposing students to curricular content and various forms of pedagogy, including modelling and situational practice. For example, allowing students to observe professional athletes play a game helps them understand how to successfully participate better than learning the rules. Teachers not only teach specific tasks but also imbue concepts with sociocultural significance. Students adapt differently based on their prior exposure to various subcultures, internalizing and effectively using these tools in different contexts. 

Vygotsky argued that psychological development derives from individuals appropriating meaning from historical and sociocultural contexts, not from biological structures or the behavioural responses of the individual (Minick, 2005, p. 4). According to his theory, as humans develop, they gradually absorb the information, knowledge, norms, and wisdom needed to operate within society's cultural, social, and economic systems. He states that we "become ourselves through others" and argues that all cognitive development occurs on a social level before being internalized on an individual level (Sætra, 2022, p. 6). While these 'others' can be static sources of information such as books, development is best accomplished when they are other, more experienced, members of society such as parents, teachers, and older siblings. These more knowledgeable others (MKOs) mediate cultural contexts for the individual through modelling, exposition, discussion, or scaffolding, increasing or decreasing the complexity of concepts or phenomena to create a mutual understanding. This mediation is inherently a social process because both the MKO and the learner must adapt to each other, using a dialectical method to share knowledge. This process is demonstrated in the following video: 

Vygotsky argued this process relies heavily on "the mediation of behaviour by signs and sign systems", particularly speech (Minick, 2005, p. 5). Whether it's a red octagon or an anxious glance, the world is full of signs; attaching meaning to these signs provides containers for our thoughts. When we learn to speak, we attach words with concepts and use these concepts to build an understanding of the world. The language of thought differs from expressed language, with both being mediated by social context and interactions with others (Fodor, 1972, p. 3). Vygotsky emphasized that thought and language are interconnected but not identical since some thoughts are amorphous and unable to be expressed using speech. 

In semiotic mediation, the relationship between signifiers and signifieds is influenced by both individuals and society; society and 'others' provide cultural contexts, but it is up to the individual to successfully connect the right definition to the right concept. Since signs and signifiers vary widely in social and cultural contexts, effective mediation requires correctly internalizing socially accepted meanings attached to different concepts. Understanding what words correspond to which objects, behaviours, etc., is vital for communication, critical thinking, and learning. The internalization of these signs through social interactions helps individuals build a nuanced and contextually relevant cognitive framework, forming the foundation of learning.

Correct mediation involves an understanding of the historical context and meanings passed down through generations, information that is best transmitted socially due to its fluidity (Gajdamaschko, 2015, p. 333). Due to the volume of languages and cultures, and the opportunity for subjective interpretation, the holistic meaning of a concept is constantly in flux and difficult to define; what a word means is often determined by mutual understanding or specific cultural events. Vygotsky identified speech and social interaction as key to overcoming this problem, arguing that intersubjectivity (a shared understanding) is instrumental in intrasubjectivity (one's understanding) (Minick, 2005, p. 4). For example, how many of these Gen Z slang terms do you understand? If so, how did you learn their meaning?