Digit Span

Measure your working memory capacity with this classic cognitive assessment.

What is the Digit Span Test?

The Digit Span test is one of the oldest and most widely used measures of working memory capacity. You hear or see a sequence of digits and must recall them either in the same order (Forward Digit Span) or in reverse order (Backward Digit Span). This simple task reveals a great deal about your cognitive capacity.

Digit Span has been part of intelligence testing since the early 1900s and remains a core component of major assessment batteries including the Wechsler Adult Intelligence Scale (WAIS).

What Does Digit Span Measure?

Working Memory

Working memory is your brain's "mental workspace"—the system that temporarily holds and manipulates information during cognitive tasks. Think of it as your cognitive RAM: the information you can actively hold in mind while thinking.

Forward Digit Span

Measures:

• Short-term memory capacity: How much you can hold at once
• Attention: Ability to focus and encode information
• Phonological loop: The verbal rehearsal system

Backward Digit Span

Measures:

• Working memory manipulation: Transforming information mentally
• Executive function: Planning and sequencing
• Cognitive load management: Holding while processing

Backward span is more cognitively demanding because you must hold the sequence while mentally reversing it.

The Science Behind Digit Span

The Magic Number Seven

In 1956, psychologist George Miller published a famous paper identifying the limits of short-term memory. He found that most adults can hold about 7 items (±2) in immediate memory—whether they're digits, letters, words, or other chunks of information.

This "magic number" has been refined by subsequent research:

• Pure short-term storage may be closer to 4±1 items
• Chunking and rehearsal strategies extend apparent capacity
• Individual differences range from about 5 to 9 items

Working Memory Model

Psychologist Alan Baddeley proposed a multi-component model of working memory:

1. Central Executive: Directs attention and coordinates processes
2. Phonological Loop: Holds and rehearses verbal information
3. Visuospatial Sketchpad: Holds visual and spatial information
4. Episodic Buffer: Integrates information from multiple sources

Digit Span primarily taps the phonological loop, with backward span also engaging the central executive.

How the Test Works

Test Procedure

Forward Digit Span:

1. Examiner presents a sequence of digits (e.g., "3-7-4")
2. You repeat the sequence in the same order
3. Sequence length increases with each trial
4. Testing continues until you fail two sequences of the same length

Backward Digit Span:

1. Examiner presents a sequence (e.g., "5-2-8")
2. You repeat the sequence in reverse order ("8-2-5")
3. Same progression as forward span

Scoring

• Span Score: Longest sequence correctly recalled
• Total Trials: Number of trials passed at all lengths
• Comparison to norms: How your performance compares to same-age peers

Typical Performance

Forward Digit Span:

• Average adult: 6-7 digits
• Range: 5-9 digits

Backward Digit Span:

• Average adult: 5-6 digits
• Usually 1-2 digits shorter than forward span

Understanding Your Results

High Scores (8+ Forward, 7+ Backward)

Suggests:

• Strong working memory capacity
• Efficient encoding and rehearsal strategies
• Good attention and concentration
• Likely advantages in learning and reasoning tasks

Average Scores (6-7 Forward, 5-6 Backward)

Indicates:

• Typical working memory capacity
• Adequate for most daily cognitive demands
• May benefit from memory strategies for complex information

Lower Scores (5 or below Forward)

May suggest:

• Limited working memory capacity
• Possible attention difficulties
• Benefit from external memory aids
• May struggle with complex instructions

Forward-Backward Gap

The difference between forward and backward span is informative:

• Small gap (1 digit): Strong executive control
• Large gap (3+ digits): Possible executive function difficulties

Practical Applications

In Daily Life

Working memory affects:

• Following instructions: Multi-step directions require holding information
• Mental arithmetic: Carrying numbers, solving problems in your head
• Reading comprehension: Holding earlier parts while reading new ones
• Conversations: Tracking multiple points in discussion
• Planning: Holding goals while organizing steps

In Education

Working memory predicts:

• Reading acquisition
• Mathematical ability
• Following classroom instructions
• Note-taking effectiveness
• Test performance

For learners with lower working memory:

• Break instructions into smaller chunks
• Use written reminders and checklists
• Provide visual supports
• Allow extra processing time
• Minimize distracting information

In Career

Working memory matters for:

• Complex problem-solving
• Managing multiple priorities
• Learning new skills quickly
• Adapting to changing demands
• Holding client/project details

How to Improve Working Memory

Evidence-Based Training

N-Back Training:

• The most researched working memory intervention
• Some studies show improvement in working memory and fluid intelligence
• Requires consistent practice over weeks
• See our N-Back guide for details

Other approaches:

• Dual-task training
• Complex span tasks
• Adaptive working memory programs

Lifestyle Factors

Sleep:

• Critical for memory consolidation
• Sleep deprivation dramatically impairs working memory
• Consistent sleep schedule helps

Exercise:

• Aerobic exercise improves cognitive function
• Acute exercise can temporarily boost working memory
• Long-term fitness supports brain health

Stress Management:

• Chronic stress impairs working memory
• Mindfulness can help by reducing cognitive load of worry
• Adequate rest and recovery

Strategy Development

Rather than increasing raw capacity, many people benefit from strategies:

Chunking:

• Group digits into meaningful units
• "5-8-3-1-7-6" becomes "583-176"
• Uses fewer working memory slots

Rehearsal:

• Actively repeat information
• Verbal and subvocal rehearsal maintain traces
• "Maintenance rehearsal" extends duration

Visual Encoding:

• Create visual images for numbers
• Spatial arrangement on mental screen
• Can supplement verbal encoding

Association:

• Link digits to meaningful information
• Patterns, dates, familiar sequences
• Creates retrieval hooks

Factors That Affect Performance

Age

Working memory capacity:

• Develops through childhood (adult capacity by ~15)
• Peaks in early adulthood
• Gradually declines with aging
• Significant individual variation

Anxiety

Test anxiety:

• Consumes working memory resources
• Creates competing thoughts and worries
• Can significantly depress scores
• Relaxation techniques help

Attention

Attention lapses:

• Miss encoding of initial digits
• Lose rehearsal thread
• External distractions problematic
• Optimal testing conditions important

Fatigue

Cognitive fatigue:

• Depletes executive resources
• Reduces effective capacity
• Test when well-rested
• Morning often optimal for many

Clinical Applications

Neuropsychological Assessment

Digit Span helps identify:

• Attention deficits (ADHD)
• Working memory impairments
• Early cognitive decline
• Effects of brain injury
• Learning disabilities

Unusual Patterns

Clinicians look for:

• Very low backward relative to forward (executive dysfunction)
• Very low forward span (encoding/attention issues)
• Inconsistent performance (motivation or attention problems)
• Discrepancy with other cognitive abilities

Common Misconceptions

"Memory is Memory"

Working memory is distinct from:

• Long-term memory: Permanent storage of information
• Autobiographical memory: Personal experiences
• Procedural memory: Skills and habits

"Low Digit Span Means Low Intelligence"

Working memory is one component of intelligence:

• Correlates modestly with IQ (~0.40-0.50)
• You can have average working memory with high fluid intelligence
• Strategies can compensate for lower capacity

"Working Memory Can't Change"

Working memory:

• Can improve with training (though debate continues about transfer)
• Varies based on state (sleep, stress, etc.)
• Benefits from strategy development
• Shows plasticity through practice

Related Assessments

Explore other cognitive assessments:

• N-Back: Training task that may improve working memory
• Stroop Test: Measures attention and cognitive control
• Trail Making: Assesses processing speed and mental flexibility

Further Reading

• Baddeley, A. (2012). Working memory: Theories, models, and controversies
• Miller, G. (1956). The magical number seven, plus or minus two
• Engle, R. (2002). Working memory capacity as executive attention

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Take the free Digit Span Test at innerquest.app/digit-span