Introduction

The Chronos is a USB-based response and stimulus device manufactured by PST and can be used in combination with E-Prime. Optimal timing in responses an audio presentation can be achieved by using the Chronos.

Availability, support and advice

A Chronos device can be borrowed from SOLO through the Helpdesk (reservations tile). When using a Chronos a Chronos driver is required, which should come automatically with an E-Prime 3 installation.

SOLO provides support for Chronos devices and its usage is recommended when E-Prime is used and optimal timing in audio or response collection is desired. The Chronos can also be used for voice recording and presenting stimuli in the form of LED lights (it has 5 fully programmable RGB LED’s). Additionally, the Chronos can be used for triggering external devices, although options that do not require the use of a Chronos are usually preferred.

Response collection with Chronos

The 5 buttons on the Chronos can be used to collect responses with millisecond accuracy, see DEVICE: Chronos as a Response Device [24491] for more info.

Short instruction to add Chronos to your experiment and use as response device:

• Attach the Chronos to your PC
• Add Chronos as a Device to your experiment (Edit ⇒ Experiment ⇒ Devices ⇒ Add ⇒ Chronos).
• Add the Chronos as response device (Input Mask) to any of the objects that require a response: Go to the Duration/Input tab of the Properties of an object. Under Input Masks, click Add... and select the Chronos. The 5 buttons are numbers 1 - 5, left to right. 

Presenting Audio with Chronos

The Chronos can be used to present sound with minimal and constant sound onset latencies (delay), for more information, see E-Prime 3.0 Live Stream: Chronos Audio and INFO: Chronos as a Sound Output Device [24493].

Short instruction to add Chronos to your experiment and use as sound device:

• Attach the Chronos to your PC
• Add Chronos as a Device to your experiment (Edit ⇒ Experiment ⇒ Devices ⇒ Add ⇒ Chronos).
• In the Devices tab, move the Chronos device up to any place above the Sound device.
• Set the API of the Sound device to Chronos: in the Devices tab, double-click on the Sound device and select Chronos in the dropdown menu next to API. 

Important considerations when using Chronos to reduce the sound delay:

• You can set Chronos in different modes (Mix Mode in the Audio Out tab in the Chronos device). Mode1 is used when one sound is played at a time. This mode is the fastest (delay of approx. 1 ms) and used most of the time. Mode2 is used when playing multiple sounds at the same time. This mode is a little slower (about 7 ms delay), but the sound onset latency is very consistent (sound onset latency should be the same as Buffer Size).
• For most optimal timing: have audio files that are compatible with 48 kHz and 16 bit stereo.
• To play a sound that is presented through the Chronos device, it is important that they have enough buffer time. This also depends on the size of your sound file. The sound’s playing time x 10 seems to work well.
• Getting Chronos to play sounds repetitively and properly can be quite frustrating. There seem to be some issues with the Chronos which causes some sounds, when being played more than once, to become distorted. Some sounds will sound very faint, others will be played two times in a row when they should not. This issue can be circumvented by trying the following:
  • Add at least 1 second of silence to the end of the audio file (Audacity can be used to do this).
  • Do not use an absolute file path for the Filename, but instead refer to an attribute when setting the sound filename.
  • Use a SoundOut object instead of an InLine to play sound files.

Resources

• Chronos Operator Manual. This manual can be found under Start ⇒ Chronos (only when Chronos is installed), or can be downloaded here: Chronos® | Psychology Software Tools (pstnet.com).
• DEVICE: Chronos as a Response Device [24491].
• INFO: Chronos as a Sound Output Device [24493].
• TIMING: Chronos Timing Article [24513].
• Chronos help. In E-Studio, go to Edit ⇒ Experiment ⇒ Devices ⇒ Chronos and click on the question mark icon.