Input Enhancement

Input enhancement (IE) is the deliberate manipulation of input to increase the perceptual salience of target linguistic features, making them more likely to be noticed and processed by learners. The term was introduced by Sharwood Smith (1991, 1993), who argued that the gap between input and intake could be narrowed by drawing learner attention to specific forms within otherwise meaning-focused material. IE operates at the implicit end of the attention-drawing spectrum -- it makes features more prominent without necessarily providing explicit rules or metalinguistic explanation.

Theoretical Basis

IE is grounded in Schmidt's (1990) Noticing Hypothesis, which holds that conscious noticing of linguistic features in the input is a necessary condition for those features to become intake. If learners do not attend to a form, it cannot be acquired -- no matter how much input they receive.

Sharwood Smith (1993) defined input as "the potentially processable language data which are made available, by chance or by design, to the language learner" and intake as "that part of input that has actually been processed and turned to knowledge of some kind." IE is the instructional bridge between the two: it increases the probability that target forms will cross the threshold from input to intake.

This positions IE within Focus on Form (Long, 1991) -- an approach that draws learner attention to linguistic features during meaning-focused activity, rather than through isolated grammar lessons.

Types of Input Enhancement

Textual Enhancement (TE)

The most researched form of IE. Target features in written text are made visually salient through typographical manipulation:

Bolding, italicising, or CAPITALISING target forms
Underlining or highlighting with colour
Increasing font size
Using different font styles or colours
Combining multiple cues (e.g., bold + colour)

The learner reads for meaning but encounters enhanced forms that are harder to ignore. The key is that the enhancement is embedded in a communicative text, not isolated in a grammar exercise.

Input Flood

Repeated, high-frequency exposure to a target form within meaning-focused material, without typographical manipulation. The sheer volume of encounters increases the probability of noticing. Less directive than TE but easier to implement.

Auditory Enhancement

Manipulation of spoken input to increase the salience of target features: stress, intonation changes, repetition, slowed delivery, or exaggerated articulation of target forms.

Research Findings

The effectiveness of IE -- particularly textual enhancement -- has produced mixed results:

Noticing: TE generally succeeds in increasing noticing of target forms, as measured by eye-tracking, think-aloud protocols, and recognition tasks.
Intake/Acquisition: The evidence for whether increased noticing leads to measurable acquisition gains is less consistent. Some studies show positive effects on form recognition and controlled production; fewer show effects on spontaneous use.
Comprehension trade-off: Some research suggests TE can reduce reading comprehension because learners divert attention from meaning to form. This is more likely when the enhancement is very heavy or when learners are explicitly told to attend to enhanced features.
Explicit instruction interaction: IE appears more effective when combined with some degree of explicit attention-drawing (e.g., being told to pay attention to highlighted items) than when used alone. This aligns with Sharwood Smith's own observation that IE operates on a continuum from implicit to explicit.
Duration of exposure: Single-session TE rarely produces lasting effects. Sustained, repeated enhancement over multiple exposures is more promising.

Practical Guidelines

Embed enhancement in texts learners read for genuine communicative purposes -- not grammar worksheets
Limit enhancement to one or two target features per text to avoid cognitive overload
Use multiple enhancement types (bold + colour) for greater salience
Tell learners to pay attention to enhanced items -- research favours this over purely incidental exposure
Combine IE with follow-up activities: noticing tasks, Consciousness-Raising Tasks, or brief form-focused discussion
Sustain enhancement across multiple lessons rather than relying on one-off exposure

Input enhancement connects to Input as the raw material being manipulated, to the Noticing Hypothesis as its theoretical justification, to Focus on Form as the broader instructional approach it belongs to, and to Input Processing as the cognitive framework explaining how learners connect form and meaning during comprehension. It complements Consciousness-Raising Tasks as another technique for drawing attention to form within meaningful activity.