In ESP, the main concern of the research and the materials is on the language analysis.  The language that we used in everyday life is the reflection of the human thought processes. The better way in learning language is actually not based on analysis the nature of the language but more to the understanding the structures and processes in the mind. But, it still has difficulties because we only know a little about the way people in learning something. The techniques, method, and content of language learning just only can be improved by the action in the classroom.  Language that we learn must have the theories, and in this case we must describe the theories in development of language according to the needs of the learners.
After the establishment by the psychology as the respectable subject of scientific enquiry in the early twentieth century, we can identify six main stages of the development of language.
1.   Behaviorism: learning as habit formation
        This is the first theory of learning by Pavlov in Soviet Union and Skinner in the United States. In this theory said that learning is the connection process of habit formation and given value by quality of the frequent action of continuous stimulus response.
        This theory has the large impact in the learning psychology and in language teaching. This theory provided the theoretical to support the use of Audio-lingual Method of the 1950s and 1960s. This method is very good because it is concluding a set of guiding methodological principles which is based on the behaviorist stimulus response concept and secondly on as assumption that second language learning should reflect and imitate the process of mother tongue language. The processes are:
1.   Never translate
2.   New language should always deal with these processes: hearing, speaking, reading, and writing.
3.   Frequent repetition is essential to effective learning.
4.   All errors must be immediately corrected.
        The basic exercise technique of behaviorist methodology is pattern practice in which the language that being used is in the form of language laboratory drills. These are the example of language from scientific English and business English:
a.    The liquid was heated. When the temperature reached 100oC, the heating was stopped.
The liquid was heated until the temperature reached 100oC.
b.   Who’s Dr. Walker?
She’s consultant, isn’t she?               
2.   Mentalism: thinking as rule-governed activity
        From the Audio-lingual method, there was considerable empirical evidence among language teachers because the method was not delivering the good result. The reason why they argued that because in the language learning process, the learners still translating things, asked for rules of grammar, found repeating things and sometime failed to learn something even though they already learn the thing so many times.
        There was the time when Chomsky could success in the behaviorist theory, but because there was concept of ‘generalisation’ in behaviorist theory that he could not explain that, so he dismissed this concept. His conclusion of the theory was thinking must be rule-governed: a finite, fairly small, set of rules enables the mind to deal with the potentially infinite range of experiences it may encounter.
        In the learning language, having thinking as rule-governed activity was also the step in learning which learning not only consist of forming habit, but also acquiring rules where the process in which the experience of somebody is being used by the mind to formulate hypothesis. The, the hypothesis will be tested and modified by subsequent experience. The mind that is being used not only response to a stimulus, but in here the individual stimuli is used in order to find the underlying pattern or system in learning language. The knowledge then being used of the system in a situation to predict what is going to happen, what is an appropriate response for it.
3.   Cognitive code: learners as thinking beings
In behaviorist theory, the learners pretend to be a passive receiver of information, but in cognitive theory, the learners are being the active processor of information. The learning process and using a rule make the learners to think and use their mental power to understand the rule from the mess data and find the appropriate time or situation to use the application of rule. Therefore, in cognitive theory, learning is a process in which the learner tries to make a sense of data. Learning can also means that the learner has managed to force some sort meaningful interpretation or pattern on the data. In other word that we learn by thinking and trying to make sense of what we see, feel, and hear.
        In cognitive theory, the basic technique teaching that usually used is the problem-solving task. These are the example of problem solving task:

  

More recently, the cognitive view of learning has significant impact of ESP through the development of courses to teach reading strategies. The ESP projects have made the students aware to theory reading strategies so the learners will easy to understand the text in foreign language.
        Cognitive view is already solved the problem that appear in behaviorist theory because in here the students are the focus of the learning process. But, actually cognitive view is not enough yet, because if we want to complete the process, we need an affective view too.
1.   The Affective Factor: learners as emotional beings
        People think, but they also have feelings. It is one of paradoxes of human nature that, although we are all aware of our feeling and their effect on our action, we invariably seek answers to our problem in rational terms. It is as if we believed that human beings always act in a logical and sensible manner. This attitude affects the way we see learners – more like machines to be programmed (‘I’ve taught them the past tense. They must know it.’) than people with likes and dislike, fears, weaknesses and prejudices. But learners are people. Even ESP learners are people. They may be learning about machines and systems, but they still learn as human beings. Learning, particularly the learning of a language, is an emotional experience, and the feelings that the learning process evokes will have a crucial bearing on the success or failure of the learning.
        The importance of the emotional factor is easily seen if we consider the relationship between the cognitive theory tell us that learners will learn when they actively think about what they are learning. But this cognitive factor presupposes the affective factor of motivation. Before learners can actively think about something, they must want to think about it. The emotional reaction to the learning experience is the essential foundation for the initiation of the cognitive process. How the learning is perceived by the learner will affect what learning, if any, will take place.
        We can represent the cognitive/affective interplay in the form of a learning cycle. This can either be a negative or a position cycle. A good and appropriate course will engender the kind of positive learning cycle represented here:
        The relationship between the cognitive and emotional aspect of learning is, therefore, one of vital importance to the success or otherwise of a language learning experience. This brings us to a matter which has been one of the most important elements in the development of ESP – motivation. The most influential study of motivation in language learning has been Gardner and Lambert’s (1972) study of bilingualism in French speaking Canada. They identified two terms of motivations instrumental and integrative.
  • Instrumental motivation is the reflection of an external need. The learners are not learning a language because they want to (although this does not imply that they do not want to), but rather because they need to. The need may derive from varying sources, the need to sell things to speakers of the language; the need to pass an examination in the language; the need to read text in the language for work or study. The need may vary, but the important factor is that the motivation is an external one.
  • Integrative motivation, on the other hand, derives from a desire on the part of the learners to be members of the speech community that uses a particular language. It is an internally generated want rather than an externally imposed need.
        Gardner and Lambert’s conclusion was that both forms of motivation are probably present in all learners but each exercises a varying influence, depending on age, experience and changing occupational or social needs.
        Motivation, it appears, is a complex and highly individual matter. There can be no simple answers to the question; ‘what motivates my students?’ Unfortunately the ESP world, while recognizing the need to ask this question, has apparently assumed that there is a simple answer; relevance to target needs. In practice this has been interpreted as meaning Medical texts for the student of Medicine, Engineering English for the Engineer and so on. But, as we shall see when we deal with needs analysis, there is more to motivation than simple relevance to perceived needs. For the present, suffice it to say that, if you students are not fired with burning enthusiasm by the obvious relevance of their ESP materials, remember that they are people not machines. The medicine of relevance may still need to be sweetened with the sugar of enjoyment, fun, creativity and a sense of achievement: ESP, as much as any good teaching, needs to be intrinsically motivating. It should satisfy their needs as learners as well as their needs as potential target users of the language. In other words, they should get satisfaction from the actual experience of learning, not just from the prospect of eventually using what they have learnt.
2.   Learning and Acquisition
        Much debate has recently centered on the distinction made by Stephen Krasben (1981) between learning and acquisition. Learning is seen as a conscious process, while acquisition proceeds unconsciously. We have not in this section paid much attention to this distinction, using the two terms interchangeably. This reflects our view that for the second language learners both processes are likely to play a useful part and that a good ESP course will try to exploit both.
3.   A Model for Learning
        In the light of the ideas we have discussed we will now present a model of the learning process, which will provide a practical source of reference for the ESP teacher and course designer.
The reasons why we have pictured the mind as operating:
  • Individual items of knowledge, like the towns, have little significance on their own. They only acquire meaning and use when they are connected into the network of existing knowledge.
  • It is the existing network that makes it possible to construct new connections. So in the act of acquiring new knowledge it is the learner’s existing knowledge that makes it possible to learn new items.
  • Items of knowledge are not of equal significance. Some items are harder to acquire, but may open up wide possibilities for further learning. Like a bridge across a river or a tunnel through a mountain, learning a generative rule may take time, but once it is there, it greatly increases the potential for further learning .this is why so often learning appears to progress in leaps and bounds. For a long time it might appear that little progress is being made; then suddenly the learner makes an enormous leap to a higher level of competence. Think of these leaps as the crossing of rivers, mountains and other major obstacles.
  • Roads and Runways are not built haphazardly. They require planning. The road builder has to recognize where problems he and work out strategies for solving those problems. In the same way the learner will make better progress by developing strategies for solving the learning problems that will arise.
  • A communication network is a system, if the road builder can see the whole system, the planning and construction of the roads will be not easier. Language is a system, too. If the learner sees it as just a haphazard set of arbitrary and capricious obstacles, learning will be difficult, if not impossible.
  • Last, but not least, before anyone builds a road, crosses a river or climbs a mountain, they must have some kind of motivation to do so. If they could not care less what is beyond the mountains, dislike the people who come from there or are simply afraid of travelling, the chances of communication links being established are minimal. First of all, there must be a need to establish the links. In ESP, this need is usually taken for granted. But, as anyone who has set out on a long and possibly difficult journey will know, a need is not enough. You can always find an excuse for not going. The traveler must also want to make the journey. And the traveler, who can actually enjoy the challenges and the experience of the journey, is more likely to want to repeat the activity. So, with learning, a need to acquire knowledge is a necessary factor, but of equal, if not greater importance, is the need to actually enjoy the process of acquisition.