Experiment Completion

The completion phase is the final stage of the participant experience. This guide explains how experiments end, how to configure completion screens, and how to handle different completion scenarios.

Overview

When participants reach the end of an experiment, the system handles:

Session finalization: Mark participant as complete
Completion screen: Thank you message display
Data finalization: Ensure all data is recorded
Redirect handling: Send to Prolific or custom URL (if configured)
Compensation tracking: Record completion for payment

Duration: Typically 5-10 seconds (configurable)

Completion Flow

┌──────────────────────────────────────────────────────────┐
│                   COMPLETION SEQUENCE                    │
├──────────────────────────────────────────────────────────┤
│                                                          │
│  1. Final State Completed                               │
│     └─ Last experimental state reaches end              │
│                                                          │
│  2. Session Finalized                                   │
│     ├─ Mark participant session as "completed"          │
│     ├─ Record completion timestamp                      │
│     └─ Finalize data recording                          │
│                                                          │
│  3. Completion Determined                               │
│     ├─ Check completion type (normal, timeout, error)   │
│     └─ Determine outcome code                           │
│                                                          │
│  4. Completion Screen Displayed                         │
│     ├─ Show thank you message                           │
│     ├─ Display completion code (if Prolific)            │
│     └─ Start countdown timer                            │
│                                                          │
│  5. Redirect (if configured)                            │
│     ├─ Wait for countdown                               │
│     ├─ Construct redirect URL                           │
│     └─ Automatic redirect to Prolific or custom URL     │
│                                                          │
│  6. Cleanup                                             │
│     ├─ Close WebSocket connections                      │
│     ├─ Stop media streams                               │
│     └─ Clear local state                                │
│                                                          │
└──────────────────────────────────────────────────────────┘

Completion Outcomes

Normal Completion (SUCCESS)

When It Occurs:

Participant completes all experimental states
Reaches final state successfully
No errors or timeouts

What Participants See:

┌────────────────────────────────────────┐
│   Thank You for Participating!         │
│                                        │
│   You have successfully completed     │
│   the study.                           │
│                                        │
│   Completion Code: A1B2C3D4            │
│                                        │
│   Redirecting in 5 seconds...          │
│                                        │
│   [Return to Prolific]                 │
└────────────────────────────────────────┘

Data Recorded:

experiment.completed event
Session status: completed
Completion timestamp
Final state data
Total experiment duration

Prolific Integration:

Outcome Code: SUCCESS
Payment: Full compensation
Redirect: https://app.prolific.co/submissions/complete?cc=XXXXXX

Best For:

All standard experiments
Data collection studies
Survey experiments

Early Exit

When It Occurs:

Participant closes browser mid-experiment
Navigates away from experiment
Connection lost permanently
Explicit exit button clicked

What Happens:

Session marked as incomplete
Partial data preserved
No completion code generated
No redirect

Data Recorded:

experiment.exited event (if detected)
Session status: incomplete
Exit timestamp
Last completed state
Partial duration

Prolific Integration:

Outcome Code: None (no completion)
Payment: No compensation
Status: Participant can be replaced

Handling:

// Early exit detected
window.addEventListener('beforeunload', () => {
  // Record partial completion
  recordEvent({
    eventType: 'experiment.exited',
    state: currentState,
    reason: 'browser_close'
  });
});

Timeout Completion

When It Occurs:

Participant inactive for too long
Maximum session duration exceeded
Waiting room timeout
State timeout (if configured)

What Participants See:

┌────────────────────────────────────────┐
│   Session Timeout                      │
│                                        │
│   Your session has timed out due to   │
│   inactivity.                          │
│                                        │
│   Partial compensation may apply.     │
│                                        │
│   Completion Code: T1M2E3O4            │
│                                        │
│   Redirecting in 5 seconds...          │
└────────────────────────────────────────┘

Data Recorded:

experiment.timeout event
Session status: timeout
Timeout timestamp
Last active state
Reason for timeout

Prolific Integration:

Outcome Code: TIMEOUT
Payment: Partial compensation (if configured)
Redirect: Custom Prolific return code for timeout

Configuration: Set timeout duration in experiment settings:

Default: No timeout (unlimited)
Recommended: 2-3x expected duration
Minimum: 1.5x expected duration

Technical Issue Completion

When It Occurs:

System error during experiment
Server connection lost
Critical component failure
Data recording failure

What Participants See:

┌────────────────────────────────────────┐
│   Technical Issue                      │
│                                        │
│   We encountered a technical problem. │
│   This was not your fault.             │
│                                        │
│   You will receive full compensation. │
│                                        │
│   Completion Code: E1R2R3O4            │
│                                        │
│   Please return to Prolific.           │
└────────────────────────────────────────┘

Data Recorded:

experiment.error event
Session status: technical_issue
Error details
Error timestamp
Affected component

Prolific Integration:

Outcome Code: TECHNICAL
Payment: Full compensation (good faith)
Redirect: Standard completion URL
Note: Participant can be replaced

Handling:

// Technical issue detected
try {
  // Experiment code
} catch (error) {
  logger.error('Critical error:', error);
  completeExperiment({
    outcome: 'TECHNICAL',
    error: error.message
  });
}

Configuring Completion Screens

Basic Configuration

Navigate to Experiment Settings → Completion:

Thank You Message:

# Thank You!

You have completed our study on decision-making.

Your responses will help us understand how people
make choices under uncertainty.

We appreciate your time and thoughtful participation!

Completion Screen Duration:

Default: 5 seconds
Range: 0-60 seconds
0 seconds: Instant redirect (not recommended)
5-10 seconds: Standard (recommended)
10+ seconds: For debriefing information

Custom Messages by Outcome:

{
  "completion": {
    "success": {
      "title": "Thank You!",
      "message": "You have completed the study successfully.",
      "duration": 5000
    },
    "timeout": {
      "title": "Session Timeout",
      "message": "Your session timed out due to inactivity.",
      "duration": 10000
    },
    "technical": {
      "title": "Technical Issue",
      "message": "We encountered a problem. You will receive full payment.",
      "duration": 10000
    }
  }
}

Advanced Configuration

Conditional Completion Messages: Display different messages based on:

Participant performance
Experiment condition
Completion time
Response patterns

Example:

// In final state, determine message
const performance = calculatePerformance(responses);

if (performance > 0.8) {
  showCompletionMessage('excellent');
} else if (performance > 0.5) {
  showCompletionMessage('good');
} else {
  showCompletionMessage('standard');
}

Debriefing Information: Include detailed debriefing in completion screen:

Study purpose revelation
Hypothesis explanation
How data will be used
Contact for questions
Links to related research

Example:

# Study Complete - Debriefing

## Purpose
This study investigated how people evaluate social interactions
through synchronized video viewing.

## Hypothesis
We hypothesized that shared viewing would increase social bonding
compared to independent viewing.

## What We Measured
- Your ratings of the videos
- Your conversation patterns
- Your facial expressions during viewing

## Your Data
All data is anonymous and will be aggregated with other participants.
Results will be published in academic journals.

## Questions?
Contact: researcher@university.edu

## Learn More
Visit our lab website: www.researchlab.edu

Prolific Integration

Setting Up Prolific Completion

1. Configure Prolific Study

In your Prolific study settings:

Completion URL: https://hyperstudy.io/experiment?id=EXPERIMENT_ID
Completion Code: Auto-generated by HyperStudy
Timeout Return: Configure timeout behavior
Error Return: Configure error handling

2. Configure HyperStudy Experiment

Navigate to Recruitment → Prolific Settings:

Enable Prolific Integration:

✅ Prolific recruitment enabled
Study ID: your-prolific-study-id
Completion redirect: Automatic
Completion screen duration: 5 seconds

3. Test Completion Flow

Preview Mode:

Use Prolific preview link
Complete experiment
Verify completion code appears
Check redirect works
Confirm code is accepted by Prolific

Test Scenarios:

Normal completion
Timeout scenario
Error scenario
Early exit (no code)

Completion Code Generation

How It Works:

Participant completes experiment
Backend generates unique completion code
Code format: Alphanumeric, 8-10 characters
Code linked to participant session
Code sent to frontend
Frontend displays code to participant
Redirect URL includes code as parameter

Code Structure:

Format: ABC123XY4Z
├─ A-Z: Random letters
├─ 0-9: Random numbers
└─ Length: 8-10 characters

Example codes:
- K7M2P9Q1X3
- Z9F4T8H2N6
- A1B2C3D4E5

Verification:

Each code is unique per session
Stored in database for verification
Prolific validates code with database
Multiple uses prevented

Redirect URLs

Success Completion:

https://app.prolific.co/submissions/complete?cc=ABC123XY4Z

Timeout Completion:

https://app.prolific.co/submissions/complete?cc=TIMEOUT123

Technical Issue:

https://app.prolific.co/submissions/complete?cc=ERROR123XY

Early Exit (No Code): No redirect occurs; participant remains on error page.

Handling Prolific Completion Issues

Issue	Cause	Solution
No completion code	Prolific not enabled	Enable in experiment settings
Code not accepted	Wrong study ID	Verify study ID matches
Redirect fails	Network error	Retry manually, provide code
Duplicate completion	Participant retries	Check session status first
Code lost	Browser closed	Contact researcher with session ID

Custom Redirect URLs

Non-Prolific Experiments

For experiments not using Prolific, you can configure custom redirect URLs.

Configuration:

{
  "completion": {
    "redirectUrl": "https://your-lab-website.edu/thank-you",
    "redirectDelay": 5000,  // 5 seconds
    "openInNewTab": false   // Same tab redirect
  }
}

URL Parameters: Append participant data to redirect:

const redirectUrl = `${baseUrl}?` +
  `participantId=${participantId}&` +
  `experimentId=${experimentId}&` +
  `completed=${timestamp}`;

Example Redirect:

https://your-lab.edu/thank-you?
  participantId=abc123&
  experimentId=exp456&
  completed=1703001234567

Conditional Redirects

Redirect to different URLs based on outcomes:

Configuration:

{
  "completion": {
    "redirects": {
      "success": "https://lab.edu/success",
      "timeout": "https://lab.edu/timeout",
      "technical": "https://lab.edu/error"
    }
  }
}

Use Cases:

Different landing pages per outcome
Compensation portals
Follow-up survey links
Lab website sections

Data Finalization

What Happens During Finalization

Data Recording:

Final state data saved
Completion event recorded
Session status updated
Timestamps finalized
Metadata added

Event Structure:

{
  eventType: 'experiment.completed',
  category: 'experiment',
  experimentId: 'exp_123',
  sessionId: 'room_456',
  participantId: 'part_789',
  timestamp: '2024-01-15T10:30:45.123Z',
  data: {
    outcome: 'SUCCESS',
    totalDuration: 1234567,  // milliseconds
    statesCompleted: 15,
    completionCode: 'ABC123XY4Z'
  }
}

Session Update:

{
  status: 'completed',
  completedAt: '2024-01-15T10:30:45.123Z',
  outcome: 'SUCCESS',
  duration: 1234567,
  completionCode: 'ABC123XY4Z',
  redirectUrl: 'https://app.prolific.co/...'
}

Ensuring Data Integrity

Before Completion:

Verify all critical events recorded
Check for data gaps
Validate response completeness
Confirm timestamps are sequential

During Completion:

Batch write remaining data
Wait for confirmation
Retry on failure
Log any issues

After Completion:

Session locked from further updates
Data available in dashboard
Export/download enabled
Analysis can begin

Completion Screen Examples

Simple Thank You

# Thank You!

You have completed the study.

Your participation is greatly appreciated.

[Redirecting automatically...]

With Compensation Info

# Study Complete!

Thank you for your time and thoughtful responses.

## Compensation
You will receive $5.00 credited to your Prolific account
within 24 hours.

## Questions?
Contact us at: study@university.edu

Returning to Prolific in 10 seconds...

With Debriefing

# Study Complete - Debriefing

## Purpose
This study examined how people perceive emotional expressions
in video conversations.

## What We Measured
- Your ratings of emotions
- Your response times
- Your attention patterns

## Results
We will email you a summary of our findings when the study
concludes in 3 months.

## Thank You
Your contribution advances our understanding of social perception.

[Return to Prolific]

With Performance Feedback

# Excellent Work!

You answered 92% of questions correctly!

## Your Performance
- Accuracy: 92%
- Average Response Time: 2.3 seconds
- States Completed: 15/15

You performed better than 75% of participants.

## Next Steps
Based on your performance, you're invited to participate
in our follow-up study for an additional $10.

Check your email for the invitation link.

Thank you for your participation!

Troubleshooting Completion Issues

Completion Screen Doesn't Appear

Problem: Experiment ends but no completion screen shown

Diagnosis:

Check browser console for errors
Verify final state configuration
Check completion event fired
Review session status

Solutions:

Ensure final state has completion flag
Check experiment state machine
Verify completion component loaded
Review frontend routing

Redirect Fails

Problem: Countdown completes but no redirect

Diagnosis:

// Check redirect URL
console.log('Redirect URL:', redirectUrl);

// Check browser blocking
// Look for popup blocker warnings

Solutions:

Verify URL is valid and accessible
Check browser popup blocker
Test in incognito mode
Use window.location.href instead of window.open

Duplicate Completions

Problem: Participant completes multiple times

Diagnosis:

Check session status before allowing completion
Review participant session history
Check for page refreshes during completion

Solutions:

// Prevent duplicate completions
if (session.status === 'completed') {
  // Already completed, show message
  return showAlreadyCompleted();
}

// Proceed with completion
completeExperiment();

Missing Completion Code

Problem: Prolific participant doesn't receive code

Diagnosis:

Check Prolific integration enabled
Verify backend API call succeeded
Review completion code generation logs
Check network requests in browser

Solutions:

Enable Prolific integration in settings
Verify API endpoint is accessible
Check authentication token valid
Test completion code generation manually

Best Practices

Timing

Completion Screen Duration:

✅ 5 seconds: Standard, works well
✅ 10 seconds: Good for debriefing
⚠️ 3 seconds: Too short for reading
❌ 0 seconds: Instant redirect (disorienting)

Countdown Display:

Show remaining seconds
Provide manual "Continue Now" button
Allow participant to read at own pace

Messaging

Clear Communication:

Confirm completion explicitly
Thank participants sincerely
Explain next steps clearly
Provide contact information

Appropriate Tone:

Professional but friendly
Appreciative of time/effort
Respectful of participation
Encouraging for future studies

Testing

Always Test:

Every completion path (success, timeout, error)
With and without Prolific integration
Redirect functionality
Code generation
Mobile devices
Different browsers

Next Steps

Participant Flow Guide - Complete participant journey
Prolific Integration - Detailed Prolific setup
Data Management - Accessing completion data
Experiment States - Configuring final states

Overview​

Completion Flow​

Completion Outcomes​

Normal Completion (SUCCESS)​

Early Exit​

Timeout Completion​

Technical Issue Completion​

Configuring Completion Screens​

Basic Configuration​

Advanced Configuration​

Prolific Integration​

Setting Up Prolific Completion​

1. Configure Prolific Study​

2. Configure HyperStudy Experiment​

3. Test Completion Flow​

Completion Code Generation​

Redirect URLs​

Handling Prolific Completion Issues​

Custom Redirect URLs​

Non-Prolific Experiments​

Conditional Redirects​

Data Finalization​

What Happens During Finalization​

Ensuring Data Integrity​

Completion Screen Examples​

Simple Thank You​

With Compensation Info​

With Debriefing​

With Performance Feedback​

Troubleshooting Completion Issues​

Completion Screen Doesn't Appear​

Redirect Fails​

Duplicate Completions​

Missing Completion Code​

Best Practices​

Timing​

Messaging​

Testing​

Next Steps​

Overview

Completion Flow

Completion Outcomes

Normal Completion (SUCCESS)

Early Exit

Timeout Completion

Technical Issue Completion

Configuring Completion Screens

Basic Configuration

Advanced Configuration

Prolific Integration

Setting Up Prolific Completion

1. Configure Prolific Study

2. Configure HyperStudy Experiment

3. Test Completion Flow

Completion Code Generation

Redirect URLs

Handling Prolific Completion Issues

Custom Redirect URLs

Non-Prolific Experiments

Conditional Redirects

Data Finalization

What Happens During Finalization

Ensuring Data Integrity

Completion Screen Examples

Simple Thank You

With Compensation Info

With Debriefing

With Performance Feedback

Troubleshooting Completion Issues

Completion Screen Doesn't Appear

Redirect Fails

Duplicate Completions

Missing Completion Code

Best Practices

Timing

Messaging

Testing

Next Steps