First and second language acquisition are two different ways, in which humans develop competence in languages. First language acquisition, also referred to as the L1, occurs when humans learn their first language from early childhood. Second language acquisition, also known as the L2, refers to the learning of a language as more of a conscious effort in stages after the early childhood period. Although the processes are different, there are also similarities. The formation of interlanguage while learning the L2 as well as how learning and proficiency in certain areas of the language differentiate from the L1 and L2 are just a few of the aspects in how the acquisition of the L1 and L2 differ. However, L1 and L2 acquisition are similar, in that language in the L1 is acquired in a similar order to that of the L2 and learners of the L1 and L2 need comprehensible input in order to be successful in their learning. To begin with the differences, the formation of interlanguage is unique to L2 acquisition. Interlanguage is a stage of learning as well as a system of grammatical rules that learners have up to the point until the L2 has been acquired. There are many different theories of how to describe interlanguage. Selinker was the first to introduce the term interlanguage. His theory supports that both language transfer and transfer of training have an effect on the interlanguage of the learner. Language transfer is when the learners transfer rules from their first language to the target language. The rules that transfer then become part of the interlanguage system. This also applies to rules learners are taught when learning the L2. Both sets of rules are included in the interlanguage (Gitsaki). Likewise, how the language is learned in the L1 differs from that of the L2. One of the differences in acquisition is how adults can pick up more language in a shorter period of time. children
need years to be able to form some of the most complex grammatical structures in their L1. Even though the L2 is acquired at a faster rate, in later stages, it is very difficult for learners to reach native-like proficiency in their L2, especially in the area of pronunciation. Despite learners rarely achieving native-like proficiency, L2 learners are more likely to be able to describe the grammatical features
of the target language whereas children
acquire the majority of the rules of the L1 subconsciously and cannot describe the grammatical features
of the system unless taught it formally (Vanegas). In addition, the acquisition of the L1 and L2 has its similarities, one of them being Krashen's Input Hypothesis. Both the L1 learner and the L2 learner benefit and make the most progress when the language input, they are exposed to, is one level slightly higher than the language that they are able to produce themselves. This is referred to as i + 1. i refers to the input while + 1 refers to the one level above the learners current level (Ipek 157). The sequential order, in which the L1 and L2 learners acquire certain grammatical structures, is another similarity between the two types of acquisition. Krashen has formulated a Natural Order Hypothesis that explains the order, in which both L1 and L2 learners acquire their language. The order is impartial to simplicity and cannot be influenced by the order, in which grammatical rules are taught in classrooms. One of the features
that Krashen points out is that yes-no questions
, for example, are acquired before wh- questions
generally (Kosur). Krashen's theory, however, has been disputed. There is evidence both for and against the validity of the Natural Order Hypothesis (Kosur). There are many variables that can affect the order of acquisition such as intelligence, how fast the learner is ablee to acquire the language, and the learner's first language, which can either affect the process either negatively or positively (Gitsaki). As shown above, the acquisition of the L1 and L2 can have its differences such as the existence of interlanguage in L2 learners and how learners acquire the target language and the native language. At the same time, there are similarities between the two types such as Krashen's Input Hypothesis and Natural Oder Hypothesis.