correspondem as formas da lingua.Quando um adulto aprende uma lingua estrangeira, seus conceitos (ja formados) ja possuem estruturas neurais fixas associadas as formas da lingua materna. As estruturas neurais correspondentes as novas formas da lingua estrangeira nao possuem relacao com as estruturas dos conceitos ja formados, sendo esta uma associacao mais dificil de ser estabelecida. E por isto que, no aprendizado de adultos, as dificuldades causadas pela interferencia da lingua materna sao maiores.A respeito do aprendizado de linguas na infancia e da interferencia da lingua materna, Harpaz diz:Humans are born with an ability to comprehend and generate all kinds of phonemes, but during childhood (starting from birth, and maybe before) this ability is shaped by experience such that only the phonemes of the native language are easily comprehended and generated. In adults, these abilities are much less plastic, so adult learners of a new language find it specially difficult to comprehend and generate the phonemes of the new language that are not used in their native language.At the time of learning to speak, the child learns to understand the world, and linguistic interaction forms most of the data in this learning. As a result, the learned neural structures that correspond to concepts tend to be associated with the neural structures that correspond to the words (by Hebbian mechanisms).When an older person learns a language, the concepts already have neural structures, which are quite fixed. The neural structures corresponding to the words in the new language, which are determined by the perceptual input, have no relations to the former structures, and hence the association is relatively difficult to learn. In learning a new language, the learner is not only required to perform new sequences of mental and motoric operations, but is also required not to perform the old ones. The old sequences are very thoroughly learned through practice, so it is very difficult to avoid performing them. Thus older second language learners find it very difficult not to slip back into their old language, both in terms of motoric actions (pronunciation) and mental actions (syntax structures, phrases etc.). For a young child, this is much less of a problem, because his/her language performance is much less practiced.(Harpaz, Yehouda. http://human-brain.org/myths.html. Online. Dec 1, 2007) FATORES AFETIVOS E PSICOLOGICOSA hipotese conhecida como affective filter, tambem de Stephen Krashen, explica que fatores de ordem psicologico-afetiva podem causar um impacto direto na capacidade de aprendizado, tais como:desmotivacao: e a ausencia de motivo espontaneo, causada por programas nao autenticados pela presenca da cultura estrangeira e que nao representam desafio. Tambem frequentemente causada pela frustracao de nao se ter alcancado proficiencia atraves do estudo formal ou pelo insucesso em sistemas de avaliacao (exames, notas, etc.). Experiencias anteriores de resultados negativos, podem desencorajar o aluno de uma nova tentativa. Aquele que nao se identifica com a cultura estrangeira, - ou que as vezes ate a despreza, - normalmente por falta de informacao a respeito da mesma, estara desmotivado para aprender sua lingua. Ja a crianca, por natureza tem um alto grau de curiosidade pelo desconhecido e forte sintonia com tudo