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Page Revision: 2013/08/19 02:19

Button element detects button presses and releases on standard input devices supported by DirectInput API. Such devices include keyboard, mouse, and a variety of joysticks and gamepads. The element collects timing statistics and, therefore is a default choice for recording of participant responses. The element allows using multiple input devices in parallel.

Table of Contents [Hide/Show] Snapshots Practical use     Creating a button to move to the next Event Note Properties Synchronized Internal Actions     Generic properties

Snapshots ¶

Event where there are two buttons. One triggered when z is pressed, the other when '/' is pressed.

Practical use ¶

The typical usage for the button element is detection of particular participant responses. However, you can use the button elements to provide operator's feedback to an experiment (for example, adjusting the experimental parameters with a keyboard at the runtime).

Creating a button to move to the next Event ¶

Instead of moving from one event to another by a set time interval, one may wish to move on only when a button is pressed. To do so:

Prerequisite :
One should have flow routes already defined. The flow route of the current event should be set to be triggered by condition.

1. On an event, click on "new element", under the category: "BEHAVIOURAL INPUT", select the "Button" element.
2. Navigate to the properties of the button element that you've just added.
3. Triggering mode can be changed if desired. (E.g when you first press the button, or when you press and hold the button etc...).
4. In the "Button" property, there are two ways of selecting the button. You may click on the 'Button List' and select the button that you wish to associate with this element. Alternatively you can press on the "Press Detector" tab and then press the button on the keyboard that should fire up the trigger. By default any button will cause the element to fire up.
5. Find the "Is Triggered" property and create a proxy variable such as "ButtonToContinue". (See Proxy variables if unsure how to create them).
6. In the bottom snippets plane, click on 'flow conditions', and paste the name of the proxy variable. e.g ButtonToContinue. Since this is a boolean, the flow will only continue when this boolean variable will be true (i.e the button was pressed).
   

Note ¶

The default settings allow detection only of the first button press. The following presses will be ignored. Change properties in the BEHAVIOUR group according to your requirements.)))

Properties ¶

Synchronized Internal Actions ¶

Experiment Start	Parent Event Onset	Status change between Onset/Offset	Parent Event Offset	Experiment End
	Button Press monitoring	Triggered snipped is called when the button state changes depending on the triggering mode.	Stops monitoring button

Generic properties ¶

Name	Description	Constraints	Value Type	Upon Runtime Change
Control
Input Device	Select one of the input devices currently connected to the computer. E.g Mouse, Keyboard etc..	Design Time..	String
Button	Defines a button which presses are registered by the element. If 'Any Button' selected then the element registers presses of all buttons on the device. The pressed button name is indicated by the Triggered Button property.	Design Time..	Int32
Triggering Mode	Defines the triggering mode for button. First Press Only mode is recommended for response time measurements.		enButtonTriggeringMode
Runtime status
Triggered button	Returns a system name of the triggered button. The keyboard symbol buttons are often denoted by the capital letters, like 'A', whereas the mouse and gamepad buttons are indicated by long names like 'Button 1'"		String
Is Down	Indicates whether the button is currently in the down state.	R, Read-only	Boolean
Triggering Time	Returns a local event time (in ms) of the last button triggering. The value can be used an accurate measure of the response time		clTime
Is Triggered	Indicates whether a button has been triggered at least once since the onset of the parent event. The property resets on each onset of the parent event. This property is commonly used for moving between events.		UInt64

+=== Properties inherited from clElement === Inherited properties of clElement

Name	Description	Constraints	Value Type	Upon Change
Control
Is Enabled	If set to false the element is completely omitted when the experiment is run.	Design Time..	Boolean
Title	Title of the element.	Design Time..	String