Attentional Blink Task

Version: v1 (current)

A rapid serial visual presentation (RSVP) paradigm measuring the temporal limits of visual attention.

Overview

The Attentional Blink task measures a fundamental limitation in human attention: when two targets appear in quick succession within a stream of distractors, the second target is often missed if it appears 200-500ms after the first. This phenomenon reveals the temporal dynamics of conscious perception and attentional selection.

Participants view a rapid stream of letters or digits presented one at a time at the same location. Their task is to identify two targets (e.g., letters in a different color) among distractors (e.g., black letters). The "blink" refers to the period after detecting the first target when attention is unavailable for processing the second target.

This task is widely used in cognitive neuroscience to study attention, working memory, and consciousness, with clinical applications in ADHD, aging, and neurological disorders.

Scientific Background

Classic Findings:

Temporal Window: The attentional blink is most pronounced when T2 appears 200-500ms after T1 (lag 2-5 at 100ms/item)
Lag-1 Sparing: T2 is often detected well if it immediately follows T1 (no blink at lag 1)
Individual Differences: Blink magnitude correlates with working memory capacity and age
Recovery Time: Attention recovers by ~500-800ms after T1

Key Mechanisms:

Reflects capacity limits in consolidating information into working memory
Related to P3 ERP component timing and attentional resource allocation
Demonstrates the bottleneck in conscious perception

Seminal Papers:

Raymond, Shapiro, & Arnell (1992): Original demonstration of the attentional blink
Chun & Potter (1995): Two-stage model of temporal attention
Olivers & Meeter (2008): A boost and bounce theory of the attentional blink

Why Researchers Use This Task

Attention Research: Study temporal dynamics and capacity limits of visual attention
Working Memory: Investigate the relationship between attention and memory consolidation
Clinical Assessment: Measure attention deficits in ADHD, schizophrenia, and neurological conditions
Aging Studies: Track age-related changes in attentional capacity and processing speed
Consciousness Research: Explore the neural correlates of conscious perception and awareness

Configuration Options

Timing Parameters

Parameter	Type	Default	Description
Stream duration (ms)	number	200	Duration each item is displayed in the RSVP stream (16-2000ms).
ISI (ms)	number	0	Inter-stimulus interval (blank screen between items, 0-500ms).
Fixation duration (ms)	number	500	Duration of fixation cross before stream begins (0-5000ms).
Response timeout (ms)	number	5000	How long to wait for participant response (1000-30000ms).

Visual Parameters

Parameter	Type	Default	Description
Font size (px)	number	48	Font size for stream items (8-400px).
T1 color	string (hex)	`#FF0000`	Color for first target (T1).
T2 color	string (hex)	`#00FF00`	Color for second target (T2).
Distractor color	string (hex)	`#000000`	Color for distractor items.
Background color	string (hex)	`#FFFFFF`	Background color.

Practice Trials

Parameter	Type	Default	Description
Enable practice	boolean	False	Enable practice trials with visual feedback.
Practice trials	array	`[]`	Array of practice trial configurations (same structure as main trials).

Instructions

Four instruction types are available:

Instruction Type	Description
Main instructions	Shown before task starts on a dedicated page with camera/screenshare preview.
Hint instructions	Quick reference shown via "?" button during task execution.
Practice instructions	Shown before practice trials begin (if practice enabled).
Trials instructions	Shown after practice, before main trials (if practice enabled).

Trial Configuration

Each trial in the trials spreadsheet is defined by:

Column	Type	Required	Description
stream_items	string or array	Yes	Comma-separated list of items in stream (e.g., 'A,B,C,X,D,E,F,Y,G').
t1_position	number	Yes	Position of first target in stream (1-indexed).
t2_position	number	Yes	Position of second target in stream (1-indexed).
t2_present	boolean	Yes	Whether T2 is actually present in the stream.
fixation_ms	number	No	Fixation duration override for this trial.
block	string	No	Optional block label for grouping trials in analysis.

Example Trial Sheet

stream_items           | t1_position | t2_position | t2_present | fixation_ms | block
-----------------------|-------------|-------------|------------|-------------|-------
A,B,C,X,D,E,F,Y,G,H   | 4           | 7           | true       | 500         | main
K,L,M,P,N,O,Q,R,S,T   | 4           | 10          | true       | 500         | main
D,E,F,W,G,H,I,J,K,L   | 4           | 5           | true       | 500         | main

Design Tips:

Stream Length: 15-20 items typical; longer streams increase task difficulty
Target Positions: Place T1 in middle third of stream to allow time for attention to engage
Lag Range: Include lag-1 (sparing), lag-2/3 (peak blink), and lag-7+ (recovery)
Item Duration: 80-120ms is standard; slower (150ms) for clinical/elderly populations

Lag Calculation

Lag = T2 position - T1 position

Lag 1: T2 immediately follows T1 (typically shows "lag-1 sparing")
Lag 2-4: Peak attentional blink period
Lag 7+: Recovery period (T2 detection improves)

Participant Experience

Unmoderated/Moderated Mode

Main Instructions: Participant reads task instructions and clicks "Start"
Practice Phase (if enabled):
- Practice instructions appear
- Practice trials with feedback (✓ or ✗)
- Feedback shows whether both targets were correctly identified
Trials Instructions (if practice was enabled): Brief reminder before main trials
Main Trials:
- Fixation cross appears (if configured)
- Rapid stream of items appears (e.g., letters/digits at 100ms each)
- Two items in the stream are colored differently (targets)
- After stream ends, participant reports both target identities
- No feedback during main trials
Completion: Task ends after all trials

Strictly Moderated Mode

Same flow, but researcher controls advancement via moderator dashboard. Participant cannot advance trials independently.

Response Collection

After the RSVP stream ends, participants:

See a response screen with input fields for T1 and T2
Type or select the two target items they saw
Click "Submit" to proceed to next trial
Have a configurable timeout period to respond

Data Output

Markers and Responses

The task records high-resolution data in two separate collections:

Markers (trial_start):

{
  "type": "trial_start",
  "ts": "2024-01-01T00:00:01.000Z",
  "hr": 1234.56,
  "data": {
    "trial_index": 1,
    "stimulus_id": "ab_0_1",
    "stream_length": 20,
    "t1_position": 7,
    "t1_value": "X",
    "t2_position": 10,
    "t2_value": "K",
    "t2_present": true,
    "lag": 3,
    "block": "main"
  }
}

Markers (stimulus_shown):

{
  "type": "stimulus_shown",
  "ts": "2024-01-01T00:00:01.700Z",
  "hr": 1934.56,
  "data": {
    "trial_index": 1,
    "stimulus_id": "ab_0_1",
    "stream_position": 7,
    "stimulus_value": "X",
    "is_t1": true,
    "is_t2": false,
    "block": "main"
  }
}

Response Data:

{
  "trial_index": 1,
  "stimulus_id": "ab_0_1",
  "source": "button",
  "t1_value": "X",
  "t1_response": "X",
  "t1_correct": true,
  "t2_value": "K",
  "t2_response": "Y",
  "t2_correct": false,
  "t2_correct_given_t1": false,
  "t2_present": true,
  "lag": 3,
  "latency_ms": 3200,
  "block": "main",
  "ts": "2024-01-01T00:00:04.200Z",
  "hr": 4434.56
}

Response Accuracy Measures

Measure	Description
t1_correct	Whether T1 was correctly identified
t2_correct	Whether T2 was correctly identified (regardless of T1)
t2_correct_given_t1	T2 correct AND T1 correct (key measure for blink magnitude)

Summary Artifact

At task completion, a JSON summary is generated (ab_summary_<taskIndex>.json):

{
  "task_kind": "attentional_blink",
  "task_index": 0,
  "total_trials": 30,
  "overall": {
    "total": 30,
    "valid_responses": 30,
    "t1_correct": 27,
    "t1_accuracy": 0.9,
    "t2_correct": 20,
    "t2_accuracy": 0.667,
    "t2_correct_given_t1": 18,
    "t2_accuracy_given_t1": 0.667,
    "mean_rt_ms": 3200,
    "timeouts": 0
  },
  "by_lag": {
    "2": {
      "total": 10,
      "t2_accuracy_given_t1": 0.4,
      "t1_accuracy": 0.9
    },
    "3": {
      "total": 10,
      "t2_accuracy_given_t1": 0.45,
      "t1_accuracy": 0.9
    },
    "7": {
      "total": 10,
      "t2_accuracy_given_t1": 0.85,
      "t1_accuracy": 0.9
    }
  },
  "attentional_blink_magnitude": 0.45,
  "trials": [...]
}

Key Metric: attentional_blink_magnitude = T2|T1 accuracy at long lags (7+) - T2|T1 accuracy at short lags (2-4). Positive values indicate a blink effect.

Design Recommendations

General Guidelines

Item Duration: 80-120ms is standard; slower (150ms) for clinical/elderly populations
Stream Length: 15-20 items typical; longer streams increase task difficulty
Target Positions: Place T1 in middle third of stream to allow time for attention to engage
Lag Range: Include lag-1 (sparing), lag-2/3 (peak blink), and lag-7+ (recovery)

Recommended Trial Counts

Study Type	Trials per Lag	Total Trials	Lag Conditions
Standard Research	10-12	40-60	1, 2, 3, 7
Clinical Assessment	6-8	24-32	2, 4, 7
Detailed Lag Curve	6-8	42-56	1, 2, 3, 4, 5, 6, 7

Population-Specific Adaptations

Children (8-12 years):

Slower presentation (120-150ms/item)
Shorter streams (12-15 items)
Fewer trials (20-24 total)
Mandatory practice with extensive feedback

Older Adults (65+):

Slower presentation (120-150ms/item)
High-contrast colors
Larger font size (60-72px)
More practice trials

Clinical Populations:

Slower timing and fewer trials
Consider single-target control condition
Include breaks between trial blocks
Use digits instead of letters if reading impairment present

Example Configurations

Standard Attentional Blink:

Stream: 20 items, 100ms each
T1 Position: 7
T2 Lags: 1, 3, 5, 7
Targets: Colored letters among black letter distractors
Trials: 10 per lag condition (40 total)

Clinical Assessment:

Stream: 15 items, 120ms each (slower for clinical populations)
T1 Position: 5
T2 Lags: 2, 4, 6
Targets: Colored digits among black digit distractors
Practice: Mandatory with feedback
Trials: 8 per lag (24 total)

Lag-1 Sparing Study:

Stream: 20 items, 100ms each
T1 Position: 8
T2 Lags: 1, 2, 3, 4, 5, 6, 7
Focus on comparing lag-1 (sparing) with lag-2/3 (blink)
Trials: 6 per lag (42 total)

Common Issues and Solutions

Issue: T1 Accuracy Too Low

Symptoms: T1 accuracy below 70%

Solutions:

Increase item duration to 150-200ms
Reduce stream length to 12-15 items
Use high-contrast colors for targets
Increase font size

Issue: No Attentional Blink Observed

Symptoms: T2|T1 accuracy similar across all lags

Solutions:

Verify lag timing is correct (should be 200-500ms between targets at 100ms/item)
Ensure T1 position allows attention to engage (position 5-8 in stream)
Check that item duration is fast enough (80-120ms)
Increase distractor-target similarity

Issue: Ceiling/Floor Effects

Symptoms: T2|T1 accuracy >90% or <20% across all lags

Solutions for Ceiling:

Reduce item duration (faster RSVP)
Increase stream length
Make distractors more similar to targets

Solutions for Floor:

Increase item duration (slower RSVP)
Reduce stream length
Use more distinctive target colors
Add more practice trials

Issue: Participants Missing Instructions

Symptoms: Confusion about reporting both targets

Solutions:

Emphasize both targets must be reported in instructions
Practice until participants understand the dual-target requirement
Provide examples showing both target positions

Issue: Response Timeout Issues

Symptoms: High rate of incomplete responses

Solutions:

Increase response timeout window to 8000-10000ms
Simplify response interface
Remind participants they need time to recall both targets

References

Raymond, J. E., Shapiro, K. L., & Arnell, K. M. (1992). Temporary suppression of visual processing in an RSVP task: An attentional blink? Journal of Experimental Psychology: Human Perception and Performance, 18(3), 849-860.
Chun, M. M., & Potter, M. C. (1995). A two-stage model for multiple target detection in rapid serial visual presentation. Journal of Experimental Psychology: Human Perception and Performance, 21(1), 109-127.
Olivers, C. N., & Meeter, M. (2008). A boost and bounce theory of temporal attention. Psychological Review, 115(4), 836-863.
Dux, P. E., & Marois, R. (2009). The attentional blink: A review of data and theory. Attention, Perception, & Psychophysics, 71(8), 1683-1700.

Related Tasks: Visual Short-Term Memory, Change Blindness, Backward Masking

Overview​

Scientific Background​

Why Researchers Use This Task​

Configuration Options​

Timing Parameters​

Visual Parameters​

Practice Trials​

Instructions​

Trial Configuration​

Example Trial Sheet​

Lag Calculation​

Participant Experience​

Unmoderated/Moderated Mode​

Strictly Moderated Mode​

Response Collection​

Data Output​

Markers and Responses​

Response Accuracy Measures​

Summary Artifact​

Design Recommendations​

General Guidelines​

Recommended Trial Counts​

Population-Specific Adaptations​

Example Configurations​

Common Issues and Solutions​

Issue: T1 Accuracy Too Low​

Issue: No Attentional Blink Observed​

Issue: Ceiling/Floor Effects​

Issue: Participants Missing Instructions​

Issue: Response Timeout Issues​

References​

Overview

Scientific Background

Why Researchers Use This Task

Configuration Options

Timing Parameters

Visual Parameters

Practice Trials

Instructions

Trial Configuration

Example Trial Sheet

Lag Calculation

Participant Experience

Unmoderated/Moderated Mode

Strictly Moderated Mode

Response Collection

Data Output

Markers and Responses

Response Accuracy Measures

Summary Artifact

Design Recommendations

General Guidelines

Recommended Trial Counts

Population-Specific Adaptations

Example Configurations

Common Issues and Solutions

Issue: T1 Accuracy Too Low

Issue: No Attentional Blink Observed

Issue: Ceiling/Floor Effects

Issue: Participants Missing Instructions

Issue: Response Timeout Issues

References