DEVICE: Chronos as a Response Device [24491]

This article applies to:

Chronos

 

Detail

Chronos as a Response Device 

One of the most important of Chronos’ functions is a millisecond accurate response device. Unlike a standard keyboard, mouse, or generic USB response device, Chronos is able to maintain the same 0ms debounce time as its predecessor, the Serial Response box.

 

Chronos USB and Millisecond Accuracy
In general, USB communication is a slow and unreliable method for receiving responses from input objects. Each object is subject to something called “debounce time”. A response device’s debounce time is the time between when the user presses a button on the response device and when the software registered that this happened. This can be problematic for reaction time-based studies where millisecond precision is paramount.

As you can see, debounce time severely impacts the quality and reliability of the response time collected from the keyboard and mouse. As a result, the response time value that you see in your data is not a reflection of when the participant pressed the button but is a result of the time that the software received the button input. This results in the participant’s actual response time being lost due to communication issues.

Chronos is able to get around this limitation of USB communication. It does this by having a processor built inside it that individually timestamps each button response the very same millisecond that it is registered on the Chronos device. This then frees up the USB communication to take as long as it needs to pass these responses from Chronos to E-Prime. When E-Prime receives this data, it does not look at when it came in, it looks at the timestamp that Chronos put on the device when it first came in. So, while Chronos is still subjected to the same USB latency as other devices, it is able to still record data with millisecond accuracy.

 

How to Add Chronos To an Experiment
When designing a task with Chronos, adding it to the experiment is as easy as adding a keyboard or mouse. E-Prime 3.0 will, by default, install all of Chronos’ drivers and devices, so there is no additional installation required. All you need to do is plug Chronos into any USB adapter on your computer, the rest of the work has been done for you. For the sake of convenience, Chronos comes equip with a status indicator when being plugged in. The front LEDs will flash blue 3 times to indicate that Chronos is ready to being collecting data. Also, verify that the Status indictor in the back is green. If either one of these are different, please contact Technical Support.

 

Once the Chronos device is connected to any USB port on the computer, it is time to set up your E-Prime experiment. Since Chronos is already installed, it should already be listed in Studio’s list of Devices (as seen below). 
 

Image 1 Adding a Chronos device.

 

Double click on Chronos to add it as a device to your experiment. Once Chronos appears in your list of Devices, no further editing is needed. Unlike the Serial Response box, E-Prime is able to auto-detect Chronos. If you would like to verify that E-Prime can see the connected Chronos, simply double click on the Chronos device in the E-Prime’s Device manager and select the Chronos Identity Manager (next to the Chronos Device Index property) and you will see your Chronos in the list of available devices (as seen below).

 

 
Image 2 Chronos Auto-Detect Functionality

This will verify that E-Prime can see your listed Chronos and is ready to collect data with it.

Chronos Input Mask
Adding Chronos as an Input Mask is as easy as adding a keyboard or mouse. With Chronos in your experiment’s Device Manager, simply click on the E-Object (e.g. Slide, TextDipslay, ImageDisplay, etc…) to which you would like your participants to respond and open the object’s Property page and Duration/Input tab. Here, just click Add and select Chronos from the list of available Input Masks (as shown below).
 

Image 3 Adding a Chronos Input Mask

 

If you would like more information on adding an Input Mask to E-Prime and its accompanying properties, please see the following article: E-STUDIO: Input Devices, Input Masks, and Echoes [22723].

 

Chronos Response Options
Once you have verified that E-Prime can see the connected Chronos and added it as an Input Mask to an E-Object, the next step is to determine how you want Chronos to interact with your experiment. Unlike some other response devices, Chronos offers a wide array of response possibilities. While its functions as a button response box are the highlight of this article, Chronos has an array of response options beyond that. The table below highlights Chronos’ response capabilities and how they can be referenced in the Allowable section of any E-Object.

 

Chronos Button	Allowable Input Syntax	Description
1	1 {-1}	A press or release of the 1st Chronos button.
2	2 {-2}	A press or release of the 2nd Chronos button.
3	3 {-3}	A press or release of the 3rd Chronos button.
4	4 {-4}	A press or release of the 4th Chronos button.
5	5 {-5}	A press or release of the 5th Chronos button.
Voice Key	6 {-6}	The onset or offset time of a participant’s vocal response (microphone required).
Digital Input #1	7 {-7}	The onset or offset of a digital input through the first input pin of the Aux I/O (Aux I/O device required).
Digital Input #2	8 {-8}	The onset or offset of a digital input through the second input pin of the Aux I/O (Aux I/O device required).
Analog In 1	9 {-9}	The onset or offset of an analog signal (I/O expansion required).
Analog In 2	a {-a}	The onset or offset of an analog signal (I/O expansion required).
Analog In 3	b {-b}	The onset or offset of an analog signal (I/O expansion required).
Photosensor	c {-c}	The onset or offset time of a screen refresh (photosensor required).
Audio Left	d {-d}	The onset or offset time of when audio is recognized as being played through Chronos’ left channel.
Audio Right	e {-e}	The onset or offset time of when audio is recognized as being played through Chronos’ Right channel.
Foot Pedal 1	f {-f}	A press or release of the 1st Chronos foot pedal (foot pedal required)
Foot Pedal 2	g {-g}	A press or release of the 2nd Chronos foot pedal (foot pedal required)

 

Table 1 Available Chronos Response options, syntax and descriptions

 

NOTE: Chronos follows the "left-to-right" convention in regards to the phyiscal button numbering (1-5). Here is a visual display of the button number when viewed from the front/top of Chronos (with an attached I/O Expander in the back):

 

 

Once you have selected to what input you would like Chronos to respond and use the Syntax column to set this property in E-Prime’s Allowable field, you are ready to begin collecting data!

For a more in-depth discussion of Chronos’ ability to collect audio-based responses, please see the following article: INFO: Chronos as a Sound Output Device [24493].

If you would like to learn more about Chronos’ I/O and expansion capabilities, please see the following Knowledge Base article: DEVICE: Chronos and Triggers [24492].