Max-Planck-Institute for Psycholinguistics

MPI Tools

NESU

Nijmegen Experiment Setup

NESU Devices and Boxes

In NESU we differentiate between devices, boxes and boards. Boxes and boards are physical units coupled with NESU. Devices are logical units which are used by psychologists, such as a push-button or a voice-key. Of course, they are realized by hardware, but this is partly transparent to the user. NESU can be coupled to various external units which can be used to present stimuli or to record responses. For stimuli generation, NESU currently supports the standard VGA boards (not all chipsets work without problems), a speechserver (PC-based home-made electronic box), a Soundblaster compatible sound board, slide projectors, Hard-disk based video recorders for random video sequence presentation, special electronics used in a childlab, and tones of variable frequency. To measure responses, the following type of equipment is currently supported: eye tracking devices, EEG/MEG equipment, MRI scanners, voice keys, push button boxes, scoring keyboards, foot pedal, touch screen, mouse, pulses, and various others.

Some of these units are directly supported by the standard PC with special drivers, while others need an electronic interface to be connected to NESU. The reasons for this are mainly a difference in electronic signaling and the need for high measurement accuracy.

1. TimerServer

Its main function is to adapt to many external devices, to provide timers, to perform fast switching of acoustic channels, and to incorporate a switching matrix which avoids the need for manual cabling.

In the picture you can see to the right of the master PC a setup with a TimerServer at the bottom, a SpeechServer in the middle, and a NESU-Box on top. This might give an impression about the size of the components. The picture shows a standard NESU-setup with two monitors.

2. Hardware SpeechServer

This box is also only available at the MPI, for similar reasons as mentioned under the TimerServer. It uses the same technology and is the same size.

Its function is to present randomly selected pre-prepared speech (sound) files with a minimal delay.

3. Software SpeechServer

This SpeechServer is the counterpart of the hardware solution mentioned under 2, but is based on a standard Soundblaster compatible audio board and special home-made driver software. It also allows the user to present randomly selected sound files. In fact, the code is part of the standard NESU code.

4. VGA-Device

This device is used to present graphic or textual stimuli to the subjects and it makes use of the standard VGA-board. In one-monitor setups it is also used at the beginning and at the end to do interaction with the experimenter. In two-monitor setups a separate Hercules board is used to do the interaction with the experimenter. It should be mentioned here, that an alternative solution is in work, since Hercules boards are not sold anymore.

5. NESU-Box

This box is a smaller version of the TimerServer with fewer functions. Since it is connected to the printer port, it can be connected to standard PCs and Notebooks. It can be rebuilt by electronics specialists and it certainly is a portable solution, since its size is similar to that of a PDA with double height.

Internally it is controlled by a micro-controller chip running low-level software burned into a ROM.

A NesuBox.

6. PC-Box (also called Maxtop-Box)

This box is even smaller than the NESU-Box, i.e. it has the same purpose but fewer functions. It is also connected to the printer port, and additional PC-boxes can easily be built since its electronic circuits are comparativeley simple. The main differences between it and the NESU-Box are:

1. It does not have a power supply, i.e. it is fed by the printer port of the PC.

2. It is possible to run it from an internal battery.

3. It does not have microphone amplifiers, i.e. to run voice key based-experiments one has to have a DAT-recorder which does the amplification of the microphone signal.

A PC-or Maxtop-Box.

7. Mini-Box

This box is the smallest box available, but still guarantees measurement accuracy smaller than 1 ms. It is integrated with a double push-button box (see below) and is also connected to the printer port. Its only function is to connect two push buttons to NESU.

This picture shows a Mini-Box as well as a PushButton-Box. From the outside they look exactly the same. The difference is in the electronics inside and the connection cable. The Mini-Box has circuitry to hook it up to the printer port. The Button-Box simply is a passive device to be connected to one of the boxes mentioned above.

8. Push-Button Box

A specially designed small push-button box (usually with two push-buttons) which fits into all boxes mentioned above (except Mini-Box). It looks the same as the Mini-Box, however, it uses a different cable.

9. Exttop-Box

A specially designed box was built to equip the childlab. It is used to control various sources of light effects.

A Exttop-Box

Overview about Boxes

The following table presents a brief overview of the functions of the different boxes: