Software / Documentation / Detection Response Task

Detection Response Task Module

Cognitive workload measurement with millisecond-precision reaction time recording.

The Detection Response Task module measures cognitive workload by recording reaction times to visual stimuli. Participants respond to a red LED stimulus by pressing a button as quickly as possible. Degraded reaction times indicate increased cognitive load.

Red Scientific Hardware

Detection Response Task devices are available from Red Scientific. See our Detection Response Task product page for specifications and purchasing information.

Getting Started

  1. Connect your Detection Response Task device — Via USB (or XBee dongle for wireless)
  2. Enable the Detection Response Task module — From the Modules menu
  3. Wait for device detection — Status shows device port
  4. Start a session — To begin recording reaction times

User Interface

Real-time Chart

The main display shows:

  • Upper plot — Stimulus state (ON/OFF) over time
  • Lower plot — Reaction time bar chart for each trial

During recording, the chart scrolls to show a 60-second window of stimulus activity and reaction times.

Detection Response Task module showing stimulus timing and reaction time data

Results Panel (Capture Stats)

Field Description
Trial Current trial number
RT Last reaction time in milliseconds (or "Miss")
Responses Total button press count
Battery Battery level (wDRT only)

Device Menu

  • Stimulus: ON — Manually turn on the LED stimulus
  • Stimulus: OFF — Manually turn off the LED stimulus
  • Configure... — Open device configuration dialog

Recording Sessions

Starting a Session

When you start a recording session:

  • Device enters experiment mode
  • Chart clears and begins fresh
  • Trial counter resets
  • Stimulus cycle begins automatically

During Recording

The Detection Response Task device automatically:

  • Presents stimuli at random intervals (ISI range)
  • Records reaction time for each stimulus
  • Marks misses when no response before timeout

Each trial captures:

  • Stimulus onset time
  • Response time (or miss indicator)
  • Reaction time (response - onset)

Data Output

File Location

{session_dir}/DRT/{timestamp}_DRT_trial{NNN}_{device_id}.csv

Example: 20251208_143022_DRT_trial001_DRT_ttyACM0.csv

DRT CSV Columns (7 fields)

Column Description
Device ID Full device identifier (e.g., "DRT_dev_ttyacm0")
Label Trial/condition label, or "NA" if not set
Unix time in UTC Host timestamp when trial logged (Unix seconds)
Milliseconds Since Record Device timestamp in ms since experiment start
Trial Number Sequential trial count (1-based)
Responses Button press count for this trial
Reaction Time Response latency in ms (-1 = miss/timeout)

Example row:

DRT_dev_ttyacm0,NA,1733649120,5000,1,1,342

wDRT CSV Columns (9 fields)

Wireless DRT adds two additional columns:

Column Description
Battery Percent Device battery level (0-100%)
Device time in UTC Device's internal RTC timestamp (Unix seconds)

Example row:

wDRT_dev_ttyacm0,NA,1733649120,5500,2,1,287,85,1733649118

Timing and Synchronization

Reaction Time Measurement

Reaction Time = Device End Time - Stimulus Onset Time

The Detection Response Task device firmware measures reaction time internally with typical accuracy of 1-5 ms.

Timestamp Precision

  • Unix time in UTC: Integer seconds (host system time)
  • Milliseconds Since Record: Integer milliseconds (device time)
  • Reaction Time: Integer milliseconds

Miss Detection

A reaction time of -1 indicates a "miss" - the participant did not respond before the stimulus turned off.

Cross-Module Synchronization

Use "Unix time in UTC" to correlate DRT events with:

  • Video frames (via camera timing CSV)
  • Audio samples (via audio timing CSV)
  • Eye tracking data (via gaze CSV)
  • Visual Occlusion Goggles lens states (when synced)

Configuration

Click Device > Configure to access device settings.

Timing Parameters

Parameter Description
Lower ISI Minimum inter-stimulus interval (ms)
Upper ISI Maximum inter-stimulus interval (ms)
Stim Duration How long stimulus stays on (ms)
Intensity LED brightness (0-100%)

ISO 17488 Standard Values

Click "ISO Defaults" to apply standard parameters:

  • Lower ISI: 3000 ms
  • Upper ISI: 5000 ms
  • Stimulus Duration: 1000 ms
  • Intensity: 100%

Configuration Buttons

  • Get Config — Reads current parameters from the device
  • Upload — Sends new parameters to the device

Understanding Results

Reaction Times

Range Interpretation
200-500 ms Normal range (unloaded baseline)
>500 ms Elevated - indicates increased cognitive load
<150 ms Very fast - may indicate anticipation

Misses

A "Miss" occurs when the participant fails to respond before the stimulus turns off. Misses indicate:

  • High cognitive workload
  • Inattention to the Detection Response Task
  • Possible equipment issues (check device)

Hit Rate

The percentage of stimuli receiving valid responses. Lower hit rates indicate higher cognitive demand.

Device Types

DRT (USB)

USB-connected device with:

  • Tactile response button
  • Red LED stimulus
  • Direct USB serial communication

Connection: USB cable to computer

Port appears as: COM port (Windows), /dev/tty.* (macOS), or /dev/ttyACM* (Linux)

wDRT (Wireless DRT)

XBee-based wireless device with:

  • Same response mechanism as USB DRT
  • Battery powered for mobility
  • XBee radio for wireless data

Connection: XBee USB dongle to computer

Note: Supports multiple wDRT devices on same network

Troubleshooting

Device not detected
  1. Check USB connection
  2. Verify device is powered on (wDRT: check battery)
  3. Check that your OS recognizes the device:
    • Windows: Check Device Manager > Ports (COM & LPT)
    • macOS: Check System Information > USB
    • Linux: Run lsusb or check /dev/ttyACM*
  4. Check the log panel for connection errors
  5. Try unplugging and reconnecting
No reaction times recorded
  1. Ensure recording session is active
  2. Verify stimulus LED is blinking
  3. Check that button presses register (Responses count)
  4. Review device configuration (ISI settings)
All responses showing as "Miss"
  1. Check stimulus duration is adequate (>500 ms)
  2. Verify participant understands the task
  3. Test button responsiveness manually
  4. Check for loose connections
Configure button doesn't work
  1. Wait for device to fully connect
  2. Ensure not currently recording
  3. Check that runtime is bound (wait a moment after launch)
wDRT not connecting
  1. Verify XBee dongle is connected
  2. Check wDRT battery level
  3. Ensure devices are on same XBee network
  4. Move devices closer together