Lifelong learning and limiting factors in second language acquisition for adult students in post-obligatory education

Lifelong learning has become a key factor for adult students attempting to improve their working conditions. However, such learning has ceased to be considered a personal challenge and, instead, has become a socio-economic imposition of a hypercompetitive society. This research study analyses three major factors affecting adults’ post-obligatory education: the pressures of lifelong learning on adult students who resume education at an advanced age due to professional needs, learning limitations stemming from their inability to adapt to new teaching methodologies and their inability to learn linguistic skills. This study particularly focused on the subject of English as a second language (L2) taught in Vocational Training Programmes in Spain. Adult learners usually become aware of multiple limitations when they study English as a second language because they have not studied the subject for years. They typically share a heterogeneous classroom with young teenage students who have a higher L2 linguistic level. This is a qualitative multi-case study in which 25 semi-structured interviews with adult students were analysed. The results suggest that adult students lack adaptation skills to the more communicative and current methodologies of foreign language teaching and that there the curriculum needs adaptations to accommodate the plurality that the age factor implies in the classroom. Subjects: Educational Research; Bilingualism/ESL; Teaching & Learning


ABOUT THE AUTHORS
The author of this article specializes in Second Language Acquisition at the University of Seville (Spain). His lines of research are Language Teaching, Age Diversity and English Studies. The author has written a thesis on English teaching for adults in post-compulsory education, specifically Vocational Training Programs. In the near future, this research aims to expand internationally in order to compare how different adult students who are facing the same situation react in different countries and cultures.

PUBLIC INTEREST STATEMENT
The recent economic and social crisis in Spain has completely reshaped education. A vast number of unemployed adults over 50 years of age must now resume their studies as the only way to access the workforce again. These new students are unemployed professionals who find themselves competing against younger and highly educated candidates for job positions. Thus, they are forced to focus on lifelong learning and continue their education in order to improve their academic experience, obtain compulsory certificates and professional diplomas and learn a second or third language at an advanced age. This article examines the great psychological and motivational limitations that adult students face when they are forced to acquire a second language (in this case, English) as a result of the current Spanish social and working conditions.

Introduction
Several research studies have examined second language learning (L2) and the various factors that affect its successful acquisition. However, the educational community has not yet focused its efforts on an in-depth analysis of post-compulsory education environments in a heterogeneous age range. Among other factors, the economic crisis that Spain has suffered in recent years has increased the number of unemployed professionals who have once again enrolled in different educational programmes after years of professional experience. Such adult students who rejoin the educational journey encounter several limitations in their ability to adapt to the teaching methods currently used in the subject of English as an L2. In these classes, adult students are usually surrounded by younger students with more academic experience and language skills.
The economic crisis marks an emergent educational reality in Spain. Vocational training teachers have recently observed an increasing registration rate of students approximately fifty years of age who return to school after years of professional experience. Generally, these students are unemployed professionals who find themselves competing against younger and highly educated candidates for job positions. Thus, they are forced to focus on lifelong learning and continue their education to improve their academic experience, obtain compulsory certificates and professional diplomas and learn a second or third language. This trend has also been reported in other European studies by Egetenmeyer (2010), Schmidt-Hertha, Krašovec, and Formosa (2014) and Halttunen, Koivisto, and Billett (2014). Adult students experience numerous limitations when they return to education after years of academic discontinuity and find themselves struggling with the current teaching methodologies to become re-accustomed to academic habits, especially in the language learning field.
Little attention has generally been given to this topic. Nationwide, there are no clear references to adult students in national decrees or study plans and very few authors have examined this new reality, with isolated exceptions such as the Spanish studies by Muñoz (2010) on the L2 age constrains. Therefore, the majority of the studies mentioned in this research were conducted in other European countries, in similar educational contexts and with students with similar characteristics. The Attention to Diversity or Special Needs In our National Law (LOMCE: National Law for the Improvement of Educational Quality), pays no special attention to adult learning or lifelong learning regarding educational assistance. In this sense, this project arises from the need to reveal this new educational situation and bring to light all the limitations and obstacles that Spanish adult students face in English L2 classrooms.
The main objective of this qualitative research is to analyse the factors that influence the acquisition of a target language by adult students pursuing lifelong learning. The evidence for the learning limitations of a second language (in this case, English) are explored in diverse age groups of Spanish Vocational Training Programmes from the perspective of adult students who restart their education after a long academic hiatus. Through a multi-case qualitative study, the learning limitations of a target language in heterogeneous age groups in Spanish vocational training programmes are investigated and analysed.

Adult students and lifelong learning
The lifelong learning process characteristically addresses a wide range of students with different needs and objectives and suggests that teaching should be adapted to such plurality. Adult students encompass a group that has very specific and delimited objectives and who possess a great cognitive maturity broadened by their professional experiences right up to the time they restart their education. However, when tackling adult second language learning, adult students encounter a double barrier that limits their teaching-learning process. On the one hand, adult students have cognitive limitations that hinder second language acquisition (SLA) at an advanced age; on the other hand, the majority of adult students face affective limitations when they begin studying an L2 at their current age.
Lifelong learning is an increasingly relevant concept that has been studied in depth by the educational community in recent decades. According to studies by various authors concerning adult students from other countries (Arthur, 2009;Glastra & Hake, 2008;Kirton, Lall, & Gillborn, 2003;Laal, 2012;Rubenson, 2006;Teunissen & Dornan, 2008), lifelong learning is an educational paradigm through which education is conceived as an indispensable and continuous element in an individual's lifespan that functions as a means to achieve stable and evolutionary training in competencies, knowledge and attitudes.
As Glastra and Hake (2008) note, globalization and individualization have radically changed both the economic system and people's personal lives in post-industrial nations. To survive the hypercompetitiveness and volatile nature of today's labour market, we need a workforce that is committed to permanent education, has up-to-date knowledge and the flexibility to continue to pursue educational training in the future. According to Laal (2012) and Kristensson Uggla (2008), lifelong learning implies that education is diverse, adapted to the individual and available throughout our lives. According to Laal's (2012) studies, the benefits of lifelong education can be categorized into three fundamental spheres: dealing with and managing the rapid changes in society, capitalizing on better job opportunities and obtaining personal enrichment. Lifelong learning is seen as a way to create opportunities for adults who want to advance and thrive in their academic lives.
However, in this study we observed that Spanish adult students restarting their education become members of this group of lifelong learning "followers" by imposed obligation rather than by love of learning or in the spirit of personal or professional betterment. The economic and social situation of the country regarding unemployment forces them to pursue academic training at an advanced age. In this professional and economic predicament, it is unclear whether such lifelong learning continues to have the same characteristics or if it is self-imposed and conceived as the last possible opportunity adult students have. Such students must now deal with various factors such as pressure, anxiety, stress, lack of motivation, low self-esteem and most of these factors are caused by the L2 subject. Moreover, adult students are prone to compare themselves with other younger students due to the hypercompetitiveness found in today's workforce (Castañeda, 2016).
In this context, lifelong learning can no longer be framed in a flattering and enriching context, but must instead be regarded as a real and overwhelming factor clashing with a reality that increasingly suffocates adult students and that "may pose a danger to their motivation levels and well-being" (Glastra & Hake, 2008, p. 89). Therefore, to what extent is lifelong education an option for adults who wish to pursue lifelong education and improve their professional lives? At what point did this option become the only path forward for the millions of unemployed Spaniards?

Age constraints in second language acquisition (SLA)
Adult students who have recently restarted their education generally show greater life experience and have previous knowledge that helps them assimilate certain content in an easier way, relate concepts more meaningfully and use that knowledge in their present lives. However, this situation changes when we study their performance in second language acquisition. Adult learners often lack the level of linguistic knowledge that their younger peers possess because of factors that stem from a double aspect. On the one hand, there are cognitive factors related to neuroplasticity loss. Neuroplasticity begins to decrease after adolescence, making it practically impossible or very difficult for adult students to reach a native language level, especially when considering the small amount of "input" to which they have access in instructional learning (Krashen, 2009;Park & Reuter-Lorenz, 2009;Reuter-Lorenz &Cappell, 2008 andVanhove, 2013). On the other hand, there are affective and motivational factors that are determinant because the loss or reduction in motivational levels induces anxiety in language classes and often leads to academic failure (Dornyei, Csizer, & Nemeth, 2006;Dornyei & Ushioda, 2009;Hall, 2013;Lasagabaster, 2014 andMuñoz, 2010).
Younger students achieve better results than adult students and seem to be able to deal more easily with foreign languages due to the two main reasons discussed above. Adult students also present several factors that could hinder their learning and that support Lenneberg's highly acclaimed hypothesis of "better at a younger age" (Lenneberg, 1967, p. 74). Among these limiting factors, we can distinguish cognitive and affective factors that influence the acquisition of the target language by adult students.

Cognitive limitations
Among the cognitive factors, we can observe: • A decrease in memory levels: Adult students generally present a reduced ability to memorize, which limits learning when acquiring the second language lexicon and grammar. This fact frequently leads to the belief that translation is an indispensable tool for learning the language and to feeling a systematic need to search for equivalences in their native language (Birdsong, 2006 andKäpplinger &Robak, 2014).
• Loss of sensory acuity: According to several authors, including Birdsong (2006), "older students lose their ability to imitate sounds and to memorize, […] consequently they are forced to start a production process based on trial/error and the oral response is decidedly slower" (Birdsong, 2006, p. 120). Thus, in addition to the cognitive factors associated with late language acquisition, adult students must also face progressive losses in sensory acuity that have accumulated since their adolescence.
• Tendency to fossilization: Adult students tend to fossilize their knowledge of the target language. They generally tend to systematize errors, and their lack of correction or habit can lead to the repetition of such errors and, consequently, the lack of acquisition. The most commonly investigated areas in the field of fossilization are morphosyntax and pronunciation (Birdsong, 2006;Krashen, 2009 andSingleton, 2001).
• L1 1 Transfer: Adult learners generally feel a more constant need to transfer the knowledge they possess in their L1 to learning a second language. Such transfer can result in a positive outcome when the common characteristics of certain languages encourage learning through equivalences and comparisons. However, behavioural theories warn that there is a thin line between facilitation of an L2 through punctual positive transference and the constant and negative interference of L1 in all L2 skills (Käpplinger &Robak, 2014 andSingleton, 2001).

Affective limitations
Among the affective factors, we can observe: • Language anxiety: Anxiety is an important variable in adult L2 learning because students face an elevated pressure to acquire a second language at the same pace or rhythm as their younger peers. Frequently the outcome is not as positive as adults would expect, which leads to stress and a very high pressure in class. In recent studies, Gkonou, Daubney, and Dewaele (2017) argue that language anxiety is a complex and dynamic construct and that it is linked to psychological variables such as self and personality.
• Self-concept: Adult students' self-concept is also crucial, and it clearly and directly affects motivation in L2 class (Mercer, 2011). Adult students restart their studies completely demotivated, and their self-confidence levels are a barrier to language acquisition. They tend not to value themselves and believe they cannot succeed in L2 learning-a fact also influenced by constant comparisons with their younger counterparts. Adult students usually present a distorted selfconcept or image due to a lack of confidence in themselves and insecurities towards L2 learning and new methodologies.
• Learning success: Each adult student attempting L2 learning has a distinct and unique way to approach the concept of success in learning Mori, 2007 andGobel, Thepsiti, &Pojanapunya, 2010). In the context of Vocational Training Programmes, adult students need to realize that success in L2 learning does not stem from an in-depth knowledge of every grammatical rule or an extended and varied lexicon, but rather from the ability to communicate and transmit information, regardless of the linguistic performance itself.
• L2 enjoyment: Teachers constantly seek to increase student motivation. Interest and enjoyment towards learning a foreign language are the key points of success in linguistic education. When teaching a second language subject in age-heterogeneous contexts, a sense of enjoyment must be found. Teachers should find a way to motivate their students through new insights and strategies that consider age diversity to help reduce language anxiety (Deawele & MacIntyre, 2014).
This present study reveals the affective and cognitive factors that influence the acquisition of second languages by adult students who restart their educational journey of lifelong learning when they enrol in Vocational Training Programmes in groups of diverse ages. Through qualitative interviews conducted with adult students, this study collects real testimony that frames this new educational reality.

Method
The main objective of this qualitative research is to analyse the factors that influence the acquisition of a target language by adult students pursuing lifelong learning. The learning limitations of a second language (in this case, English) are evidenced and explored in diverse age groups of Spanish Vocational Training Programmes from the perspective of adult students restarting their education after a long academic hiatus.
The results presented in this article are based on a multiple-case qualitative study structured by following Robert E. Stake's (2006) work on multiple case analysis. The information obtained in this study reveals the experiences of adult students in Intermediate and Advanced Vocational Training Programmes in an educational institution in Spain where L2 learning has recently become compulsory. Semi-structured interviews were conducted with twenty adult students of approximately 50 years of age enrolled in Vocational Training Programmes. These adult students provided evidence and experiences about the difficulties they encountered when trying to successfully complete the programmes, especially in their English classes.

Participants
Twenty adult students, with ages ranging 43 to 62 (average age 49.2 years), were selected as participants from Intermediate and Advanced Vocational Training Programmes. All the participants attended the same educational centre (Santa Maria de los Angeles High School, Malaga) because it offers numerous Vocational Training Programmes for students of all ages; thus, we could find a great diversity in all contexts The sampling system was non-probabilistic and based on five criteria: age of the participants, prior academic experience, academic discontinuity, professional status and participants' accessibility and willingness to volunteer (see Table 1: "Research participants") Students were selected with the help of the teachers, counsellors and psychologists of this educational centre, who considered that the selected students confronted numerous limitations in language learning and were struggling with new teaching methodologies. The students were asked if they wanted to participate anonymously, to which they fully agreed.
A total of twenty semi-structured interviews were conducted. Each interview included forty-five open-ended questions formulated to collect information related to the seven categories into which this research was divided (see the Section 2.3). The research period lasted approximately four months, from February to May 2016. The adult students who participated in this research study were enrolled in different areas of the Intermediate and Advanced Vocational Training Programmes (see Table 1). https://doi.org/10.1080/23311908.2017.1404699

Data collection instruments
Two types of instruments were used to collect data in this research study. First, we conducted one semi-structured interview with the open-ended questions for each participant. A script was created prior to the interview. Each interview lasted approximately 45-60 min. Second, the participants wrote autobiographical reports in which they explained their work experiences and the reasons for their return to education.
The questions selected for this structured interview are divided into different categories for their analysis and correspond to the following factors: • affective limitations in L2 learning: these questions aim to identify the affective limitations stemming from feelings of rejection, fear of ridicule, lack of motivation and self-esteem.
• cognitive limitations in L2 learning: these questions focus on fossilization, decrease in memory levels, loss of sensorial acuity and L1 transfer. • L2 methodological strategies: these questions reveal the difficulties that older students restarting their education have assimilating new learning methodologies.
• lifelong learning motivation: the main objective of these questions was to determine whether adult students were continuing their education voluntarily.
• prior work experience: these questions address the importance of lifelong education as a career complement.
• prior language experience: these questions are intended to investigate whether it is easier to learn or retake the study of a second language when adult students have previously studied an L2.
• academic discontinuity: these questions investigate whether the academic hiatus that adult students have experienced is a limiting factor for future academic success.
In the results of this research, we focus primarily on the categories of "L2 affective limitations" and "L2 cognitive limitations" because these turned out to be more suitable for the focus of our study. From these main premises, we will tackle the other categories as well, but in a secondary manner.

Data analysis
The data analysis was performed through a qualitative data analysis application called Weft QDA.
After the data were transcribed and stored, the results were categorized by dividing and grouping the information into the seven different blocks to speed up and simplify the analysis. The information was compiled and subdivided into specific codes (for example, "experience of adult students with intonation of words" or "adult student approach to grammar", etc.). Each question shed light on various categories and the information was later compiled and divided to simplify classification according to the main purposes of our study.

Ethics
The participants' personal information remained anonymous at all times, and none of the collected information could identify them. To ensure their privacy, they signed an informed consent in which they authorized the interviewer (and, therefore, the University of Seville) to use the data provided through the investigation. In the same way, each interviewee was informed about the purposes of the interview and the purposes to be achieved, namely: publication and the use of their contributions in congresses, conferences, etc.

Results
Diversity in Vocational Training Programmes in Spain has increased over the last decade due to the increase in the enrolment rate of students over 40 and 50 years of age. This increase adds age factor to the already diverse and individualized nature of classrooms, which in the case of the L2 English subject, generally involves an extreme variability in linguistic level. Some students (often the adults) have never studied a second language; yet these students must learn the same content as younger students who present an advanced linguistic level. The latter group has recently graduated from Secondary Education and have more than ten years of experience in the L2 levels (which correspond to B2 and C1 levels according to the Common European Framework of Reference for Languages (CEFRL)).
To present the data in an orderly manner and due to space constraints, we will divide the findings of this study into the first two categories of this study abovementioned, since they widely cover most of the information specified in the other five.

L2 Cognitive limitations
Adult students present an additional academic difficulty that must be considered from the beginning; that is, loss of memory levels and a decrease in sensorial acuity. Having experienced such an extensive academic discontinuity, many adults are out of the habit of studying and have forgotten the convenient ways of acquiring knowledge and learning. They are usually frightened, overwhelmed and frustrated because they notice how their memory fails them, and their abilities are no longer what they used to be. Adult students believe that teachers should help guide them in learning or studying because they usually approach such tasks with poor methodology based on traditional conventions, in which memory is indispensable. Adult students need teachers to instil in them the usefulness of work planning, notetaking, reading to promote understanding, strategies that motivate attention. In short, it is essential to ensure that adult students are provided with the necessary tools and techniques to help them acquire successful study habits and avoid knowledge fossilization: INT 2: "It was truly difficult. Sometimes I was even afraid to sit down at the desk to start studying. I used to overthink everything and I really did not know how to study. However, my tutor helped me a lot by giving me study techniques. That is how I learned to underline, to use colours to organize the syllabus, to make schemes and summaries and, finally, to synthesize the information in order to understand and study it. This was completely new to me because I had never studied before. I had to start completely from scratch".
In all the participants we observed an important dichotomy between the absence of study habits motivated by academic discontinuity and greater experience of the knowledge imparted in the course. The participants maintain that while it is difficult to acclimate to academic life, to a certain extent the professional experience obtained in their long careers helps them understand the contents because some of the knowledge they have acquired through work experience is repeated in some way.
Similar to most of the participants, interviewee 8 explains why adult students struggle with content and knowledge fossilization at an advanced age, especially in the L2 subject: INT 8: "We adults just think differently, we have other mental structures. In advancing in age, thinking differently is complicated, especially in another language such as English. Retaining knowledge is particularly difficult at this age and I think we tend to repeat errors simply because it takes longer for us to learn structures and concepts and internalize them. The 18-or 20-year-old students seem to be perfectly adapted and comfortable in English class; myself? Well, that's different".
All the participants agree with the presumption that the ability to learn languages declines as a person grows older. In fact, they maintain that they could memorize content much faster in the past and that they were more able to acquire new knowledge, however abstract. On the other hand, they suggest that if they had begun studying languages years earlier, they would probably now have greater ease and could use their knowledge in a more practical way, instead of relying merely on translation to know what subject they are dealing with. In this sense, one of the interviewees sheds light on the fundamental differences between young and adult students in terms of neurological abilities.
INT 7: "There is a fundamental difference between the young and the adult mind. For example, when I study something I tend to forget about it in 5 min; to truly understand and grasp concepts I need to spend considerable time. This was not true when I was young. When you are young, what you learn sticks with you for the rest of your life. Not now; now it just leaves. Retention fails".
With respect to the subject of L1 interference in the learning of English and the excessive use of literal translation, one of the interviewees explains her reasoning with a very interesting metaphor. She states that she must at all times be sure what she is saying in English, and to do so, one must mentally translate, literally, from Spanish to English before expressing it. The participant compares this process with that of the transition from the state currency "Peseta" 2 to the euro. In the same way that she must calculate amounts in pesetas to understand what the value actually is, she must also translate English into Spanish to be confident of what she is saying. Through this metaphorical example, the interviewee implies that adult students must feel secure with the content under discussion at all times and that the ability to improvise so easy for the younger students is lost as they become older. Adults must know what they are saying at all times; therefore, they need an exact translation of the message to feel that confidence. Thus, the interference of Spanish to English is common among those adult students who did not receive quality language training at an early age.
INT 6: "I always have to translate everything into Spanish in my mind to be confident that I can say it in English. For example, that also happens to me with pesetas and euros-I still have to think in pesetas to understand the value of what I am handling in euros. The same thing happens to me with English. I don't know what I'm spending until I know it in pesetas; similarly, I need a constant comparison with Spanish to be able to express myself in English".

L2 Affective limitations
Age diversity in Vocational Training Programmes usually causes an important initial affective shock in both adult and young students. The traditional generational homogeneity to which students are accustomed in compulsory education gives way to a heterogeneity that is not only determined by the age difference but also includes all those factors that derive from it: different interests and motivations, different knowledge, attitudes towards learning, different sociocultural and economic levels, the pressures of the existence or absence of family responsibilities, level of maturity, emotional factors, etc.
One of the participants in this study was particularly overwhelmed by the insecurity that restarting her education alongside students who were decades younger caused her. She enrolled in a class full of students already familiar with the new teaching methodologies and skilled in the use of languages and new technologies: INT 1: "Before coming back to class I already had a huge level of anxiety because you tend to create a preconceived idea and you cannot withstand the pressure. My idea was always that people would look at me strangely and think, 'What is this old woman doing here?' However, when I started, my teachers encouraged me and gave me a lot of strength. That motivated me enough, even though my self-esteem and confidence were still a problem." In these cases, participants realize that they belong to a class with different motivations and linguistic levels-two completely different generational groups that present varied educational goals, interests, desires and abilities. Adult students see younger students as globalized subjects who are open to internationalization and are more prepared to face this new educational age. In this sense, participant number 6 feels completely alienated towards this new academic reality: INT 6: "When I saw the children who were my classmates I was both surprised and very uncomfortable because they could actually be my grandchildren. So, the situation was quite complicated. I did not consider myself a student, I considered myself a worker. That's why I felt out of place".
Under these premises, adult students face differences of both knowledge and interests with their teenage or young counterparts. In general, the heterogeneity in the age factor-which is accentuated in the English classroom-involves fundamental differences in the level of knowledge, approach to work, instrumental motivations and so on. One must consider such diversity as a benefit for the class as a whole and as a source of knowledge and experience from which the entire student body can benefit. However, that same diversity can become a double-edged sword for students if it is not used properly. Therefore, students believe that teachers should make the appropriate methodological adaptations to capitalize on age diversity for the benefit of the group and avoid cases of language anxiety and frustration: INT 13: "As an adult I come here because I want to study; just that. I cannot waste time; time is gold. I honestly cannot afford to miss a second at my age and in my situation. In contrast, the children have all the time in the world and can afford to waste it and work at their own pace. Young students are much more passive and always expect to be instructed. However, I am a more inquisitive person; you do not have to tell me anything to get me to work. In this sense, I was a little disturbed by the fact that the children were always saying, 'What do we have to do?', 'What do we do now?', 'I'm done'. I already had my homework done but I had to wait for the children to finish." INT 16: "I simply could not become accustomed to the new methods. Always speaking English in class, in groups, in public … and performing activities intended for younger students, not for people who had not studied for decades. That was really frustrating".
Adult students who have suffered an academic discontinuity usually restart their education without considering the new teaching methodologies and without study habits. Being immersed in work for many years seems to create a routine in which adults feel comfortable, and this feeling is difficult to forget. However, when this sector of the population becomes unemployed and must restart their education, their entire lifestyle must change completely to adapt to the new reality. The participants mentioned their "social" sense of "utility" and their new self-concept in several of the analysed cases because adult students feel fulfilled when they perform a professional activity and receive a well-earned salary. However, when wrested away from this routine, adult students become frustrated, which hinders their academic performance when restarting their education: INT 10: "I didn't know where I belonged anymore. I had lost my job, my economic security, my social status-everything I was. In addition, now I had to return to school with kids, which wasn't necessarily the best initial motivation for beginning a new life".
In this plural context, different generations with their respective characteristics and interests are thrown together. This fact leads the adult students to reject the possibilities that restarting their education brings to a certain degree. It also clearly leads to discouragement and an initial frustration increased by the problems of low self-esteem deriving from their work situations, creating a vicious circle that can lead to frustration and academic dropout.
INT 2: "The greatest shock was being surrounded by kids in class. It was very difficult not to see the rest of my classmates as if they were my children. Then, over time, it became a little better and I was able to establish normal social relations. However, the major problem was derived from my loss of study habits. That is, completely changing my daily routine and not performing the activities of professional life-working from 8 to 3, dealing with your co-workers, having to make important decisions, having responsibilities, and so on-losing all of this and returning to a classroom with children and study books was an enormous change".
In general, we can emphatically state that the age heterogeneity in class hindered the learning process of the participants to some extent, mainly due to affective differences such as learning enjoyment. Adult students generally emphasize their feelings of fear and anxiety when learning a foreign language because they have no prior contact with the language, and they feel embarrassed or insecure. Therefore, they consider learning a second language as an obligation rather than an interesting tool for promoting themselves in our current globalized era.
INT 19: "I see my sons watching movies in English on that Netflix, or playing games where the voices are in English, and I see that they enjoy doing what they do without even realizing it is in English. I can't do that. I just don't like it".
The case of participant number 13, age 62, is worthy of special mention. Similar to the other analysed cases, this interviewee showed an unusual reluctance to join a class where she would be surrounded by adolescents and young people, in which, by coincidence, her own daughter was also enrolled. This fact seemed to motivate her more to start the Programme. However, the age heterogeneity in the classroom and, above all, the fact that she was older than other adults who were already considered elderly-some of whom participated in this study-affected her self-esteem and frustrated her so much that she dropped out of the school to attend classes at another academic institution.
One of the events that affected this student the most occurred at the beginning of the course. This event was not necessarily part of the classroom environment nor can it be ascribed to age heterogeneity or limitations in L2. Instead, the problem came from the Counselling Department. As normally occurs during the enrolment procedure for students with special needs, the participant was called to the Counselling Department office so the counsellor could talk to her and inquire into the reasons why she had decided to restart her education at her age. The teaching department had previously informed the counselling department that this student might have learning difficulties and would present special challenges that needed to be addressed. The participant was very offended by this referral and considered it a lack of respect for her rights as a student: INT 13: "Seeing me so old, they decided to refer me to the Counselling Department. I can honestly tell you that if I have decided to retake education at this age it is because I am fully confident that I have made a good choice. I am mature enough to make my own decisions. I pondered this decision a thousand times and considered the pros and cons. This bothered me a lot. I told the psychologist, don't you worry, I am already very old and I have my feet on the ground and I know what I want. It did not seem right to me that they felt the need to ask me why I had come here. I paid my tuition and had as much right as the youngsters".
Adult students comment on the imperative need to study, retrain and obtain a certificate. This contrasts sharply with the less urgent character observed in younger students. This factor is, according to participant number 11, a fundamental difference between the younger students and the adult students, and it is the main reason for the generational abyss that exists in classrooms: INT 11: "The fundamental difference between young and adult students is, above all, feeling accountable for their obligations and having concrete objectives. Most of the students are children, so they conceive of education as something they have to do, not as a priority to survive, as it was in my case. My need was immediate, and that same need is not present in teenagers." Experiencing a new reality in the Spanish educational scene, it is evident that teachers are not yet accustomed to this type of diversity; therefore, most of the participants in this research stated that it is necessary to visualize and evidence this reality, which has hitherto not been the object of any research. The testimony of these participants shows that age, as a factor within the broad panorama of diversity, is as relevant as any other factor.

Conclusion and discussion
As established in the study objective stated above, we analysed the factors that influence the acquisition of a target language by adult students pursuing lifelong learning. The learning limitations of a second language (in this case, English) were identified and explored in diverse age groups of Spanish Vocational Training Programmes from the perspective of adult students restarting their education after a long academic hiatus.
Adult students pursuing lifelong learning face numerous obstacles regarding the new L2 teaching methodologies, which are based on a communicative approach and actual language practice. Adapting to this new experience after a long academic hiatus is usually an arduous and extensive process. Therefore, teachers should focus on students' needs and identify the areas where they need extra reinforcement. This conclusion is similar to those of previous Spanish studies by Castañeda (2016) and Muñoz (2010). As observed with these participants, the current hypercompetitiveness for jobs forces older candidates to view lifelong learning as an imposed obligation required to survive rather than as an opportunity to mould themselves and acquire new knowledge and experiences. This research analysed how the limitations of adult students learning a foreign language stem from a double perspective. First, the biological limitations that naturally come with age and restrict the ability to learn a foreign language acquisition contrasts with the faster and more natural way in which children and adolescents assimilate foreign languages. In this way, this study observed limitations in memory, difficulties in understanding certain grammatical points or expressions, lack of fluency and problems with comprehension and the production of oral messages, etc. These findings coincide with those of various studies by prior authors (Krashen, 2009;Park & Reuter-Lorenz, 2009;Reuter-Lorenz &Cappell, 2008 andVanhove, 2013). Second, affective limitations prevent adults from the learning of languages. In age-and level-diverse groups, adult students usually feel more self-conscious and less confident; this finding accords with those of previous studies by Dornyei et al. (2006), Dornyei and Ushioda (2009), Hall (2013), Lasagabaster (2014, Muñoz (2010) and Schleppegrell (2001). Adults tend to lose motivation when they discover that they learn more slowly and that they have a lower mastery level than do their younger counterparts. It is in this context where adults stop participating in class and begin to feel totally excluded and isolated from the group. They may end up feeling animosity towards the subject of English, frustrated or even dropping out.
On the one hand, we identified several cognitive factors that limit second language acquisition in adult students. Among them, the participants highlighted decreased memory levels, loss of sensory acuity, fossilization and L1 transfer as the most limiting factors when approaching the learning of a second language at an advanced age.
As analysed in this study, one notable limitation faced by adult learners when learning a foreign language is the fossilization of errors, a topic that has been widely analysed by authors such as Singleton (2001) and Birdsong (2006Birdsong ( , 2009. Students tend to assimilate concepts faster than they correct mistakes. To maintain oral fluency, they often repeat errors that have been corrected and explained before. On the other hand, the transference of the native language also implies limitations for the learning of a foreign language, as was verified by Singleton (2001) and Käpplinger and Robak (2014). This tendency is greater among adults with a longer academic discontinuity. Along this line, teachers should also be careful about how they correct errors made by adult students because poor feedback can sometimes be discouraging. The tone, the use of red ink or expressions such as a categorical "NO!" are factors that teachers must consider to avoid negatively affecting the already weak motivation, self-esteem or confidence of adults.
This study found that older students face age-related biological limitations such as the loss of sensory acuity and memory, which coincides with previous studies by Birdsong (2006) and Käpplinger and Robak (2014).
Moreover, we observed several affective factors that limit second language acquisition in adult students. Among these, participants highlight language anxiety, low self-esteem, distorted selfconcept and lack of interest in learning a second language.
Adult students' lack of adaptability is mainly observed by their disconnection from the younger students and the evident generation gap between them. Adult students may feel separated from the group because of differences in their motivation, interests and life goals. Adults need to benefit from the time they invest while back in school by setting clear goals regarding their plans after completing their programme. In this sense, as we observed in this research, they have no affinity with the rest of the group because younger students usually do not have such pressures; their motivations and interests are still to be shaped with experience. This finding is similar to previous research on L2 motivation by authors such as Dornyei et al. (2006), Ushioda (2009), Hall (2013) and Lasagabaster (2014). They state that the loss or decrease in motivational levels derived from age-diverse learning contexts induces language anxiety and often leads to academic failure.
We witnessed large levels of language anxiety among adult students, who tend to constantly compare themselves to their younger counterparts. The pressure of leaning an L2 and using it orally with new communicative methodologies affects their self-esteem and frequently causes a loss of confidence.
Throughout this study, when collecting data from all participants, we observed a common pattern repeated at every intervention. Adult students in classrooms among younger students suffer language anxiety when trying to acquire a second language. They frequently become frustrated and lose self-esteem as they compare the difficulties they experience when apprehending certain knowledge that the younger students learn easily.
Among other affective variables, we observe a general lack of self-esteem and L2 insecurity, which cause frustration in the classroom (Krashen, 2009;Lasagabaster, 2014;Mercer, 2011). Alongside these variables, we also observe a distorted self-concept in adult students restarting their education; they feel inferior with respect to the other students and think that they are insufficiently prepared to succeed in their new academic phase.
We observe a distinctive way to approach the concept of success in learning (Gobel & Mori, 2007;Gobel et al., 2010). In the education context of Vocational Training Programmes, teachers are trying to make adult students realize that success in L2 learning does not derive from a deep knowledge of every grammatical rule or from an extended and varied vocabulary, but rather from the ability to communicate and transmit information. Learning a foreign language should be done in such a way that students can find a sense of enjoyment (Deawele & MacIntyre, 2014).
Another element that seems counterproductive in terms of adult adaptation in diverse age contexts involves the new methodologies and learning strategies in foreign language instruction. Due to the traditional isolationist and not very international character of Spain, adult students who were educated in the 60s, 70s or 80s have problems adapting to the methodological implementation used in current foreign language classes, which can also be seen in the scarce Spanish research on this topic (Castañeda, 2016;Muñoz, 2010). The returning adults are not accustomed to speaking in a foreign language and simply tend to self-impose a barrier, further impeding their learning. Adult students feel insecure with the communicative approach and all the methodologies derived from it, which is the modern basis for teaching a foreign language. Sometimes they do not even try because they believe they will be unable to become as fluent as the younger students. Adult students are limited in their acquisition of foreign languages primarily by the following factors: tendency to fossilization, memory loss, resistance to change, L1 transference and loss of sensorial acuity.
Through the internationalization of Spain, exposure to other foreign cultures and the effects of globalization, new L2 methodologies have evolved to adopt more communicative and practical approaches. As can be seen in the results of this study, this changes increase the academic and professional hypercompetitiveness in the labour market; consequently, the pressures borne by students also increases progressively-and even more so at an advanced age, as also reported by Laal (2012). Teachers are aware of this change but are choosing to continue pursuing the new teaching techniques. In short, it is the adult student educated in "the old ways" who faces greater difficulties in accepting and adapting to new methodologies.
Adult students are part of a group that has a clear disadvantage vis-a-vis younger students in contexts of job search and reinsertion. The hypercompetitiveness in today's labour market favours an academic certificate over extensive professional experience. Therefore, adult students are constantly subject to comparing themselves against the younger candidates and trying to adapt to the high requirements of an increasingly globalized and digitalized society. In this study, we investigated how adult learners understand that lifelong learning is crucial and attempt by all means necessary to adapt to the strict selection process that exists today, often with negative results that lead to disappointment and frustration, as also found by authors such as Arthur (2009), Glastra and Hake (2008), Kirton et al. (2003), Laal (2012), Rubenson (2006) and Teunissen and Dornan (2008).
Educators deeply value the efforts that older students make to adapt to their new academic lives, and they work hard to raise their students' hopes and avoid frustrating them. At the same time, teachers often wonder what will happen to students over 50 years of age who restart their education as a last resort to regain access to the workforce. More significantly, teachers are concerned about the excessive competition these adults will experience against younger, more highly educated jobseekers.
Unemployed adult students face obstacles not only in acquiring new skills such as English but also because they feel emotionally and personally detached from a society that has rejected them, leaving them professionally and economically inactive. However, far from becoming resigned, many adults restarting their educations continue to hope that retraining will provide them with the skills they need to rejoin the labour market. In this case, teachers know that, regardless of the academic frustrations and dropout risks, these students will increase their opportunities by benefiting from the support of the educational community through new and practical L2 methodological adaptations and cooperative learning environments.

Funding
The author received no direct funding for this research.