Individual Differences in SLA
Individual differences (IDs) in SLA refer to the range of cognitive, affective, and personality variables that cause learners exposed to the same input and instruction to achieve different outcomes. Understanding IDs explains why a single classroom can produce such varied levels of attainment — and why no single teaching method works equally well for all learners.
Major ID Variables
| Variable | Domain | Key finding |
|---|---|---|
| Language Aptitude | Cognitive | Strongest single predictor of L2 learning rate. Carroll & Sapon (1959), Skehan (1998) |
| Motivation | Affective | Integrative Motivation and Instrumental Motivation both predict sustained effort and attainment. Gardner & Lambert (1972), Dörnyei (2005) |
| Working Memory | Cognitive | Predicts success especially under explicit learning conditions. Baddeley (2000) |
| Language Anxiety | Affective | Debilitating anxiety specific to L2 use impairs performance. Horwitz et al. (1986) |
| Age | Biological | Earlier exposure generally advantages pronunciation; the Critical Period Hypothesis remains debated |
| Willingness to Communicate | Affective/social | Determines how much L2 use a learner actually engages in — input and output volume |
| Learning style | Cognitive | Preferences for visual, auditory, kinaesthetic processing — empirical support is weaker than commonly assumed |
| Personality | Affective | Extraversion, openness, and tolerance of ambiguity correlate with some L2 outcomes |
| Beliefs about learning | Metacognitive | Learner beliefs about how languages are learned shape strategy choice and effort |
Why IDs Matter
The same instructional input produces different outcomes because learners differ in:
- How they process input — WM capacity, analytic ability, phonological memory
- How much input they seek — WTC, motivation, anxiety level
- How they respond to instruction — aptitude–treatment interactions mean that explicit instruction benefits some learners more than others
- How they sustain effort — motivation, self-regulation, grit
Dörnyei's L2 Motivational Self System
Dörnyei (2005, 2009) reconceptualised L2 motivation around three components:
- Ideal L2 self — the learner's vision of themselves as a proficient L2 user
- Ought-to L2 self — external pressures and expectations
- L2 learning experience — the immediate impact of the learning environment, teacher, and materials
This framework shifted motivation research from static trait models toward dynamic, situated accounts.
Aptitude–Treatment Interaction (ATI)
A central finding in ID research: the effectiveness of a teaching approach depends on the learner's aptitude profile. High-analytic learners benefit from explicit instruction; learners with strong phonological memory may thrive in implicit, input-rich environments. This argues against one-size-fits-all methodology.
Teaching Implications
- Varied instructional approaches within a course accommodate different ID profiles
- Learner training in learning strategies and metacognitive strategies can compensate for weaker aptitude areas
- Anxiety management (supportive classroom climate, low-stakes practice) benefits learners with high language anxiety
- Motivation is not fixed — it can be cultivated through goal-setting, identity work, and engaging materials
- Assessment should account for ID-related variation — timed tests disadvantage learners with lower WM capacity or higher anxiety
References
- Dörnyei, Z. (2005). The psychology of the language learner. Lawrence Erlbaum.
- Dörnyei, Z. (2009). The L2 motivational self system. In Z. Dörnyei & E. Ushioda (Eds.), Motivation, language identity and the L2 self (pp. 9–42). Multilingual Matters.
- Robinson, P. (Ed.) (2002). Individual differences and instructed language learning. John Benjamins.
- Skehan, P. (1989). Individual differences in second-language learning. Edward Arnold.