Affective Filter

The Affective Filter Hypothesis (Krashen 1982) proposes that emotional and attitudinal variables act as a mental barrier between input and the language acquisition device. Even when input is comprehensible and at the right level, a high affective filter prevents it from being processed for acquisition.

The Three Variables

Variable	High filter (blocks acquisition)	Low filter (enables acquisition)
Anxiety	Fear of making mistakes, judgment, embarrassment	Comfortable risk-taking, supportive environment
Motivation	Low interest, no perceived relevance	Intrinsic interest, clear personal goals
Self-confidence	Learned helplessness, negative self-image as learner	Belief in own ability to learn

The filter operates on a continuum. A learner with high motivation and low anxiety will acquire more from the same input than an anxious, unmotivated learner.

Why It Matters

The hypothesis explains a phenomenon every teacher recognizes: some learners plateau not because of insufficient input or ability, but because emotional factors shut down processing. This is visible in:

• Students who understand everything but freeze when asked to produce
• Advanced learners whose accuracy collapses under test pressure
• Children who acquire faster than adults in immersion, partly because they have lower affective filters (less self-consciousness, less fear of error)

Criticisms

• Difficult to measure. The filter is a metaphor, not a measurable cognitive mechanism. Anxiety research (Horwitz et al. 1986) confirms that language anxiety affects performance, but the mechanism is more complex than a simple filter.
• Oversimplifies affect. Emotion in SLA involves identity, investment, and social power (Norton 2000), not just anxiety and motivation as isolated variables.
• Conflates acquisition and performance. A stressed learner may perform poorly without actually having failed to acquire: the filter may affect production, not just intake.

Practical Applications

• Classroom culture matters as much as materials. Error correction style, wait time, grouping, and teacher attitude all raise or lower the filter.
• Low-stakes practice first. Activities like free writing, pair discussions, and rehearsal time let learners engage with language before high-stakes production.
• Personalise content. Learners engage more with topics they find relevant: the filter drops when motivation is intrinsic.
• Monitor your own impact. Overcorrection, public error correction, and time pressure all raise filters. Research on corrective feedback suggests recasts and delayed correction are less face-threatening.