OpenSesame script
About OpenSesame script
OpenSesame script is a simple definitional language that defines an experiment. It is not a full fledged programming language, and does not include features such a for loops. The OpenSesame script is interpreted by an OpenSesame runtime environment.
OpenSesame script is different from the Python scripts that are used in inline_script items. Python is a real programming language with all the flexibility and complexities that this entails. In contrast, OpenSesame script is used to define experiments in a simple, human-readable way.
General remarks
Keywords
Some items, such as form_base and sketchpad accept keywords. Keywords are of the form keyword=value. Keywords are optional and should fall back to a default value.
Comments
Strings preceded by a hash should be interpreted as comments.
Example
# This is a comment
Quotation
Quotation is not necessary, except around strings that contain spaces or other forms of punctuation. So the following lines should be interpreted as identical:
set my_var 'my_value'
set my_var "my_value"
set my_var my_value
However, the following lines are not. In fact, the first line is not valid, because it has an unexpected third parameter.
set my_var my value
set my_var "my value"
Types
There are no types. No distinction is made between strings, integers, etc.
Item-specific syntax
Some items have a specific syntax. This is indicated in the “Applies to” section for each of the keywords discussed below.
Resolving path names
TODO
define statement
Starts the definition of an item. After a define statement, all lines are indented by a single tab. The end of the item definition is the first string that is no longer indented. Nested define statements are not allowed.
Applies to
All items
Format
define [item name] [item type]
[item definition]
Parameters
|item name |the name of the item |
|item type |the type of the item |
Example
define get_key keyboard_response
set allowed_responses "a;x"
set description "Collects keyboard responses"
set timeout "infinite"
set flush "yes"
draw statement
Defines a visual element of a sketchpad or feedback item.
Applies to
sketchpad, feedback
Format
The format depends on the element.
draw ellipse [left] [top] [width] [height] [keywords]
draw circle [x] [y] [radius] [keywords]
draw line [left] [right] [top] [bottom] [keywords]
draw arrow [left] [right] [top] [bottom] [keywords]
draw textline [x] [y] [text]
draw image [x] [y] [path]
draw gabor [x] [y]
draw noise [x] [y]
draw fixdot [x] [y]
Parameters
|left |the left-most x-coordinate |
|right |the right-most x-coordinate |
|top |the top y-coordinate |
|bottom |the bottom y-coordinate |
|x |the x-coordinate |
|y |the y-coordinate |
|text |text string |
|path |the path to an image file |
Keywords
TODO
Example
draw fixdot 0 0
log statement
Indicates that a variable should be written to the log-file.
Applies to
logger
Format
log [variable name]
Parameters
|variable name |the name of a variable |
Example
log response_time
run statement
Indicates that an item should be run. In the case of the sequence, the order of the run statements determines the order in which items are called. In the case of the parallel plugin all items are called at the same time.
Applies to
sequence
Format
run [item name] [optional: condition]
Parameters
|item name |the name of the item to run |
|condition (optional) |the conditional statement, which determines the item is actually called. If no condition is provided, the item is always called.|
Example
run correct_feedback '[correct] = 1'
set statement
Defines single-line variables.
Applies to
All items
Format
set [variable name] [value]
Parameters
|variable name |the variable name |
|value |the variable value |
Example
set timeout 1000
Notes
Multi-line variables are defined using the __[variable name]__ notation. This is mostly useful for items that require large blocks of text. Within an item definition, each line is preceded by a single tab, which should not be interpreted as part of the text. __end__ indicates the end of the variable.
For example:
__my_variable__
This is the first line.
This is the second line.
__end__
setcycle statement
Similar to the regular “set” statement, but sets a variable only during a specific cycle of a loop. This is the script equivalent of the loop table.
Applies to
Loop
Format
Setcycle [cycle #] [variable name] [variable value]
Parameters
|Cycle # |the number of the cycle, where 0 is the first |
|variable name |the variable name |
|value |the variable value |
Example
setcycle 0 cue valid
widget statement
Adds a widget (buttons, labels, etc.) to a form. Valid keywords depend on the type of widget. The widget statement is not strictly part of the core OpenSesame syntax, but is used by the form_base plugin.
Applies to
form_base (plugin)
Format
widget [column] [row] [column span] [row span] [widget type] [keywords]
Parameters
|column |the widget's column position in the form, where 0 is left-most |
|row |the widget's row position in the form, where 0 is top |
|column span |the number of columns that the widget occupies |
|row span |the number of rows that the widget occupies |
|widget type |'button', 'checkbox', 'image', 'image_button', 'label', 'rating_scale', or 'text_input' |
Keywords
TODO
Example
widget 0 0 1 1 label text='This is a label'