The Affctive Filter Hypothesis : -

The Affctive Filter Hypothesis :-
The fifth hypothesis, the Affective Filter hypothesis, embodies Krashen's view that a number of 'affective variables' play a facilitative role in second language acquisition. These variables include motivation, self-confidence and a low level of anxiety are better equipped for success. Low motivation, low self-esteem, and debilitating anxiety can combine to 'raise' the affective filter and form a 'mental block'. Comprehensible input may not be utilized by second-language acquirers if there is a mental block. The affective filter acts as a barrier to acquisition: If the filter is down, the input reaches the LAD and becomes acquired competence; if the filter is up, the input is blocked and does not reach the LAD ( figure ) .

'Up' ^
Input----------> Filter --------> Language Acquisition Device(LAD)---------> Acquired ^ 'Down'

Figure :- The operation of the 'affective filter' (based on krashen 1982). Only when the filter is down or low is input thought to reach the language acquisition device and become acquired competence.
There is a general agreement that affective factors play a critical role in second language learning. What questionable is whether it is necessary to postulate an affective filter to explain the research findings in the field. There are two issues that deserve examination:
1)The role of affective filter in language acquisition
2)The need for an affective filter to explain individual variation in second language learning
The affective filter and language acqusition -
The filter is that part of internal processing system that sub-conciously screens incoming language based on what psychologists call 'affect' : learner's motives, needs, attitude and emotional states.
Functions of affective filter - *It determines which language models the learner will select *It determines which part of language will be attended to first *It determines when language acquistion efforts should cease *It determines how fast a learner can acquire a language
Thus the filter is thought to limit what it is that the learner attends to, what will be learned, and how quickly language will be acquired.
The affective filter and individual differences
According to Krashen, children have an advantage in language developement because their affective filter is lower. Adult learners, on the other hand, are likely to have higher affective filters because of events that occur in adolescence. Krashen argued that, adolescents tend to think that other people are concerened with the same thing that concerns them : themselves. This leads to increased self-conciousness, feeling of vulnerability and a lower self emage- all of which, interfere with language learning.
To conclude, although most researchers in the field of second language acquisition would admit that affective variables play a critical role, few would see a need to postulate an affective filter that is vague in its origin and function.