''Internalization'' can be understood in one respect as "knowing how". For example, riding a bicycle or pouring a cup of milk are tools of the society and are initially outside and beyond the child. The mastery of these skills occurs through the activity of the child within society. A further aspect of internalization is ''appropriation'', in which the child takes a tool and makes it his own, perhaps using it in a way unique to himself. Internalizing the use of a pencil allows the child to use it very much for his own ends rather than drawing exactly what others in society have drawn previously.
Perhaps Vygotsky's most important contribution concerns the inter-relationship of language development and thought. This concept, explored in Vygotsky's book ''Thought and Language'', (Russian: ''Myshlenie i rech'', alternative translation: ''Thinking and Speaking'') establishes the explicit and profound connection between speech (both silent inner speech and oral language), and the development of mental concepts and cognitive awareness. Vygotsky described inner speech as being qualitatively different from normal (external) speech. Although Vygotsky believed inner speech developed from external speech via a gradual process of internalization, with younger children only really able to "think out loud," he claimed that in its mature form inner speech would be unintelligible to anyone except the thinker, and would not resemble spoken language as we know it (in particular, being greatly compressed). Hence, thought itself develops socially.
Language starts as a tool external to the child used for social interaction. The child guides personal behavior by using this tool in a kind of self-talk or "thinking out loud." Initially, self-talk is very much a tool of social interaction and this tapers to negligible levels when the child is alone or with deaf children. Gradually, self-talk is used more as a tool for self-directed and self-regulating behavior. Because speaking has been appropriated and internalized, self-talk is no longer present around the time the child starts school. Self-talk "develops along a rising not a declining, curve; it goes through an evolution, not an involution. In the end, it becomes inner speech" (Vygotsky, 1987, pg 57).
Speaking has thus developed along two lines, the line of social communication and the line of inner speech, by which the child mediates and regulates their activity through their thoughts. The thoughts, in turn, are mediated by the [[semiotics]] (the meaningful signs) of inner speech. This is not to say that thinking cannot take place without language, but rather that it is mediated by it and thus develops to a much higher level of sophistication. Just as the birthday cake as a sign provides much deeper meaning than its physical properties allow, inner speech as a sign provides much deeper meaning than the lower psychological functions would otherwise allow.
Inner speech is not comparable in form to external speech. External speech is the process of turning thought into words. Inner speech is the opposite; it is the conversion of speech into inward thought. Inner speech, for example, contains predicates only. Subjects are superfluous. Words are also used much more economically. One word in inner speech may be so replete with sense to the individual that it would take many words to express it in external speech.
Zone of proximal development (ZPD) is Vygotsky’s term for the range of tasks that a child can complete. The lower limit of ZPD is the level of skill reached by the child working independently (also referred to as the child’s actual developmental level). The upper limit is the level of potential skill that the child is able to reach with the assistance of a more capable instructor.
Vygotsky viewed the ZPD as a way to better explain the relation between children’s learning and cognitive development. Prior to the ZPD, the relation between learning and development could be boiled down to the following three major positions: 1) Development always precedes learning (e.g., Constructivism (learning theory)|constructivism): children first need to meet a particular maturation level before learning can occur; 2) Learning and development cannot be separated but instead occur simultaneously (e.g., behaviorism): essentially, learning is development; and 3) learning and development are separate but interactive processes (e.g., gestaltism): one process always prepares the other process, and vice versa. Vygotsky rejected these three major theories because he believed that learning always precedes development in the ZPD. In other words, through the assistance of a more capable person, a child is able to learn skills or aspects of a skill that go beyond the child’s actual developmental or maturational level. Therefore, development always follows the child’s potential to learn. In this sense, the ZPD provides a prospective view of cognitive development, as opposed to a retrospective view that characterizes development in terms of a child’s independent capabilities. Vygotsky, L. S. (1978). Mind in society: The development of higher psychological proceses. Chapter 6 Interaction between learning and development (79-91). Cambridge, MA: Harvard University Press.
Instructional scaffolding|Scaffolding is a concept closely related to the idea of ZPD, although Vygotsky never actually used the term. Scaffolding is changing the level of support to suit the cognitive potential of the child. Over the course of a teaching session, a more skilled person adjusts the amount of guidance to fit the child’s potential level of performance. More support is offered when a child is having difficulty with a particular task and, over time, less support is provided as the child makes gains on the task. Ideally, scaffolding works to maintain the child’s potential level of development in the ZPD. An essential element to the ZPD and scaffolding is the acquisition of language. According to Vygotsky, language (and in particular, speech) is fundamental to children’s cognitive growth because language provides purpose and intention so that behaviors can be better understood. Vygotsky, L. (1934/1986). Thought and language. Cambridge, MA: MIT Press. Through the use of speech, children are able to communicate to and learn from others through dialogue, which is an important tool in the ZPD. In a dialogue, a child's unsystematic, disorganized, and spontaneous concepts are met with the more systematic, logical and rational concepts of the skilled helper. Santrock, J (2004). A Topical Approach To Life-Span Development. Chapter 6 Cognitive Development Approaches (200 – 225). New York, NY: McGraw-Hill. Empirical research suggests that the benefits of scaffolding are not only useful during a task, but can extend beyond the immediate situation in order to influence future cognitive development. For instance, a recent study recorded verbal scaffolding between mothers and their 3- and 4-year-old children as they played together. Then, when the children were six years old, they underwent several measures of executive function, such as working memory and goal-directed play. The study found that the children’s working memory and language skills at six years of age were related to the amount of verbal scaffolding provided by mothers at age three. In particular, scaffolding was most effective when mothers provided explicit conceptual links during play. Therefore, the results of this study not only suggest that verbal scaffolding aids children’s cognitive development, but that the quality of the scaffolding is also important for learning and development. Landry, S. H., Miller-Loncar, C. L., Smith, K. E., & Swank, P. R. (2002). The role of early parenting in children’s development of executive processes. Developmental Neuropsychology, 21, 15-41.