Knowledge Base

External Data

What Is External Data and How Do I Work with It?

External Data

External data can be data that have been acquired with a separate Data AcQuisition (DAQ) system, such as a MindWare or BIOPAC system. This can be, for example, physiological data (e.g., ECG, EEG, blood pressure, skin temperature), environmental data (e.g., temperature, humidity) or eye-tracking data.

To be able to work with external data in The Observer XT, your license must include the External Data Module.

N-Linx

BIOPAC AcqKnowledge 5, Tobii Pro Lab, Tobii Pro Studio 3.4.7 and Tobii Glasses software and the Bitbrain EEG acquisition software can be integrated with The Observer XT using the Noldus network communication protocol N-Linx. This simplifies the setup and ensures synchronization. For these systems, separate technical notes are available.

• Technical Note - BIOPAC MP System - The Observer XT
• Technical Note - Tobii Pro Eye Trackers - The Observer XT
• Technical Note - Tobii Glasses - The Observer XT
• Technical Note - Bitbrain EEG - The Observer XT

In addition to this, technical notes are available for integration between The Observer XT and Mindware Biolab and SMI eye-trackers. You can download these technical notes from the MyNoldus section of the Noldus website.

What Can I Do with External Data?

You can import external data into The Observer XT and synchronize them with logged events. You can then visualize, select and analyze the external data based on events. Or, the other way around, you can analyze events when external data have a certain value.

This topic focuses on the import of external data and the synchronization with logged events.

• For selecting external data, see Select Data for Analysis.
• For visualizing external data, see Visualize Data.
• For analyzing external data, see Calculate Statistics.

How Do I Work with External Data?

The procedure to work with external data in The Observer XT depends on the way these data are going to be synchronized with logged events. The Observer XT can send a synchronization signal to the DAQ system. The external data are then automatically synchronized with the events.

See External Data Acquisition with Synchronization Signal.

You can also record external data stand-alone and import these data afterwards in The Observer XT. In this case you need to synchronize the data manually.

See Stand-Alone External Data Acquisition.

Workflow

External Data Acquisition with Synchronization Signal

1. Set up The Observer XT for live observation and to send a synchronization signal to the DAQ system. The synchronization signal is an analog signal which is fed into a free analog input of the DAQ system. In the DAQ device this signal is configured equally as a standard physiological signal (e.g. ECG, EEG, EMG). The time information in this synchronization signal is stored in the external data file. See Set Up Your Experiment with Synchronization Signal.
2. Carry out a live observation and simultaneously collect the external data. See step 8 in Set Up Your Experiment with Synchronization Signal.
3. Import the external data set together with the synchronization signal into The Observer XT and link it to an observation. The Observer XT uses the synchronization signal to synchronize the external data with the events. See Import External Data as Text Files.

Stand-Alone External Data Acquisition

1. Record the external data. Optionally, record a video of your test subjects with MediaRecorder as well, or carry out a live observation in The Observer XT.
2. Export the external data as a text or EDF file.
3. Import the external data into The Observer XT. See Import External Data as Text Files or Import European Data Format Files.
4. Synchronize the external data manually with the events in The Observer XT. See Manual Synchronization.
5. Optionally, score your observation in more detail with the recorded video. See Carry Out an Observation.

What's Next?

• Optionally, make a selection of external data or events in a data profile. See Select Data for Analysis.
• Visualize the data. See Visualize Data.
• Calculate statistics on behaviors/modifiers and/or external data. See Calculate Statistics.

Set Up and Acquire External Data

What do you want to do?

• Set Up Your Experiment with Synchronization Signal
• Set Up Your Experiment with Stand-Alone External Data Acquisition
• Read About the Synchronization Signal

Set Up Your Experiment with Synchronization Signal

Aim

To have The Observer XT send a synchronization signal to your DAQ system. The synchronization signal is imported into The Observer XT with the external data and is used to synchronize the external data with the Event log.

Prerequisites

• Your license for The Observer XT includes the External Data Module.
• You have a synchronization cable.

Procedure

1. Connect your DAQ system to its dedicated computer (that is, the computer that records such data). Also connect it with the synchronization cable to the computer with The Observer XT. Use one of the computer's COM ports of the computer with The Observer XT. If the computer has no COM port, use a USB-RS232 adapter.
2. In The Observer XT, choose Setup > Project Setup > Live Observations. The Devices window opens. If not, click the Devices button.
3. Choose DAQ Settings (or any other name indicating the external data acquisition device) and click Edit Settings.
4. Under Predefined Settings, select the item corresponding to your Data Acquisition device, or create a new one.
5. Under Output Device, select how the PC with The Observer XT is connected to the DAQ system. Select the correct COM port, or Noldus Mini-IObox sync if you use a Noldus mini USB-IO box.
6. Click the Check Status button to check whether the selected port is Online. If it is Offline, check that other programs (also those not running) are not using that port. Change the port settings in those programs or uninstall them when not necessary. When you use a USB-RS232 adapter, search for the COM port from the list that is Online.
7. Under Signal Type select:
   • On-Off if your DAQ system uses a low sample rate (< 10 Hz) or samples continuously (without regular intervals). Also select this option if you use the Noldus mini USB-IO box for synchronization.
   • Time Code (TCAP) in all other cases. Enter the Sample Rate of your DAQ device. The program calculates the Minimal Sampling Time in seconds. This is the time The Observer XT needs to send the complete synchronization signal to the DAQ device at that sample rate. See The Time Code (TCAP) Synchronization Signal.
8. Start the observation as usual (see Start the Observation in Carry Out an Observation). The Observer XT now asks you to start data acquisition on your DAQ device.
9. Start the DAQ acquisition.
10. In The Observer XT, click OK.
11. After you finish the observation, export the data from the DAQ system as a text file. Name your synchronization data as 'sync' or use 'sync' as the type of Unit. The Observer XT then automatically recognizes your synchronization data upon import.
12. Continue with Import External Data as Text Files.

Notes

• It is also possible to connect the computer with The Observer XT with a USB cable to a Noldus mini USB-IO box. The synchronization cable connects your DAQ system to one of the TTL ports of the Noldus mini USB-IO box. Select Noldus Mini IObox Sync in the Output Device list in step 5. Select On-Off in step 7. Contact your Noldus sales representative if you are interested in this option.
• If you click Cancel after you clicked the Start Observation button in step 8, the observation starts anyway, but the synchronization signal is not sent to the DAQ device.
• If the DAQ system uses a filter for incoming external data, it might also affect the synchronization signal from The Observer XT. Watch the sync signal on your DAQ system; it should display square pulses.
• Automatic synchronization with the synchronization signal was tested with text export from the DAQ system only. You can also import EDF files into The Observer XT (see Import European Data Format Files), but then we recommend synchronizing manually (see Manual Synchronization).

Set Up Your Experiment with Stand-Alone External Data Acquisition

Aim

To manually start and stop acquisition with a DAQ system and import the external data into The Observer XT. The imported data must be synchronized manually with the Event log.

Prerequisites

Your license for The Observer XT includes the External Data Module.

Procedure

1. Make sure an event is recognizable in the Event log, the videos and the external data file, so that you can use it to synchronize the streams. Do so in, for example, one of the following ways:
   • Count down until you press the button to start the DAQ acquisition, and make sure you can hear this on the video file.
   • Define a dummy behavior in the Coding Scheme and score that behavior at the same moment as you start the DAQ acquisition.
   • Synchronize the clock times of both computers with a time server to make sure the time stamps of the external data files match those of the Event logs.
   • If the DAQ system does not require many computer resources, install the DAQ software on the same computer as The Observer XT. The time stamps in the external data file then automatically match the ones in the Event log.
2. In The Observer XT, choose Setup > Project Setup and then:
   • Live Observation – if you score events simultaneously with recording the external data. Optionally, record video with MediaRecorder as well. See Observe Live and Record Video with MediaRecorder in Set Up Your Project.
   • Offline Observation – if you recorded videos together with recording the external data and annotate them at a later stage. See Observation Method in Set Up Your Project.
3. Carry out the observation as usual. See Score Data in Carry Out an Observation.
4. Export the data from your DAQ system as a text or EDF file.
5. Import the external data. See Import External Data as Text Files or Import European Data Format Files.
6. Synchronize the data manually with the observation. See Manual Synchronization.

The Synchronization Signal

What Is the Synchronization Signal?

If you score events and simultaneously acquire external data, you can synchronize external and event log data with The Observer XT. This is done by sending a synchronization signal from the Observer XT PC to the external DAQ system. This synchronization signal contains time information from The Observer XT PC. This time information is used to synchronize the event log data and the associated external data after import of the external data file.

There are two types of synchronization signals:

• The On-Off synchronization signal
• The Time Code (TCAP) synchronization signal

The preferred Signal Type depends on how the external data are sampled by the DAQ system.

The On-Off Synchronization Signal

Use the On-Off signal in the following situations:

• The sample rate of the DAQ system is lower than 10 Hz.
• The collection of external data is uninterrupted.
• You use the Noldus mini USB-IO box for the synchronization signal.