There are many prominent figures in the development of second language acquisition. These people have contributed many theories and have had profound influence on the subject. They have provided some insights into what we can achieve in language as a whole. In dealing with this, I have chosen Stephen Krashen and Noam Chomsky as the prominent figures to discuss upon.
Stephen Krashen was born in Chicago, Illinois in 1941. He is professor emeritus at the University of Southern California, who moved from the department of linguistics to the Faculty of Education in 1994. He is famously known as a linguist, an educational researcher, and an activist. He also holds a black belt in Tae Kwon Do and has spent 2 years in Ethiopia teaching English and Science with the Peace Corps. He has published more than 350 papers and books, contributing to the fields of second language acquisition, bilingual education, and reading. He is credited with introducing various influential concepts and terms in the study of second language acquisition, with the most famous and widely practiced around the world is the five key hypotheses in language learning he promotes which is the acquisition-learning hypothesis, the input hypothesis, the monitor hypothesis, the affective filter, and the natural order hypothesis.
The acquisition-learning hypothesis discusses that adults have two different ways to develop competence in a language: language acquisition and language learning. Language acquisition is a subconscious process not unlike the way a child learns language. In a non-technical language, acquisition is 'picking-up' a language. Language learning, on the other hand, refers to the conscious knowledge of a second language, knowing the rules, being aware of them, and being able to talk about them. Thus language learning can be compared to learning about a language. The natural order hypothesis states that the acquisition of grammatical structures proceeds in a predictable order. For a given language, some grammatical structures tend to be acquired early, others late, regardless of the first language of a speaker. However, this does not mean that grammar should be taught in this natural order of acquisition. The monitor hypothesis asserts that a learner's learned system acts as a monitor to what they are producing. In other words, while only the acquired system is able to produce spontaneous speech, the learned system is used to check what is being spoken.
According to the affective filter hypothesis, certain emotions, such as anxiety, self-doubt, and mere boredom interfere with the process of acquiring a second language. They function as a filter between the speaker and the listener that reduces the amount of language input the listener is able to understand. These negative emotions prevent efficient processing of the language input. The hypothesis further states that the blockage can be reduced by sparking interest, providing low anxiety environments and bolstering the learner's self-esteem. He is also instrumental in the campaign to defend bilingual education which he aggressively campaigned in public forums, media talk shows, and conducted numerous interviews with journalists discussing the subject. Most recently, Krashen promotes the use of free voluntary reading during second language acquisition, which he describes as pleasure reading for the fun and relaxing. He believes that recreational reading is a very good practice for low intermediate and intermediate language acquirers.
Avram Noam Chomsky was born on December 7, 1928 in Philadelphia, Pennsylvania. He is a Jewish American linguist, philosopher, cognitive scientist and political activist. He is an Institute Professor and professor emeritus of linguistics at the Massachusetts Institute of Technology (MIT) where, as of 2008, he has taught continuously for 53 years. He is well known in the academic community as one of the fathers of modern linguistics.
In the 1950s, Chomsky began developing his theory of generative grammar, which has undergone numerous revisions and has had a profound influence on linguistics. His approach to the study of language emphasizes an innate set of linguistic principles shared by all human known as universal grammar, the initial state of the language learner, and discovering an account for linguistic variation via the most general possible mechanisms. He elaborated on these ideas in 1957's Syntactic Structures, which then laid the groundwork for the concept of transformational grammar. He also established the Chomsky hierarchy, a classification of formal languages in terms of their generative power. In 1959, Chomsky published a widely influential review of B. F. Skinner's theoretical book Verbal Behavior, which was the first attempt by a behaviorist to provide a functional, operant analysis of language. In this review and other writings, Chomsky broadly and aggressively challenged the behaviorist approaches to studies of behavior dominant at the time, and contributed to the cognitive revolution in psychology. His naturalistic approach to the study of language has influenced the philosophy of language and mind.
It is a popular misconception that Chomsky proved that language is entirely innate and discovered a ‘universal grammar’ (UG). In fact, Chomsky simply observed that while a human baby and a kitten are both capable of inductive reasoning, if they are exposed to the exact same linguistic data, the human child will always acquire the ability to understand and produce language, while the kitten will never acquire either ability. Chomsky labeled whatever the relevant capacity the human has which the cat lacks the "language acquisition device" (LAD) and suggested that one of the tasks for linguistics should be to figure out what the LAD is and what constraints it puts on the range of possible human languages. The universal features that would result from these constraints are often termed "universal grammar" or UG. The Principles and Parameters approach (P&P) make strong claims regarding universal grammar: that the grammatical principles underlying languages are innate and fixed, and the differences among the world's languages can be characterized in terms of parameter settings in the brain, which are often likened to switches.
These 2 prominent figures have provided the language as a whole, many concepts on acquisition of a second language and also on linguistics. In part due, we also have to thank them for liberating us from the gripping and fascist-like teaching of behaviorism and introducing the cognitive approach where the learning is based on the human brain capacity and ability.