Modify a timeline to set possible values for variables
set_variables(timeline, ...)
| timeline | The timeline object |
|---|---|
| ... | A set of name/value pairs defining the timeline variables |
The modified timeline object
When creating an experiment, a common pattern is to create a
series of trials that are identical in every respect except for one thing
that varies across the trial (e.g., a collection of
trial_html_button_response() trials that are the same except
for the text that is displayed). A natural way to handle this in the
jsPsych framework is to create the trial in the usual fashion, except that
instead of specifying the value that needs to be included in the
trial (e.g., the text itself) the code includes a reference to a
timeline variable. Inserting the reference to the variable
is the job of the insert_variable() function; attaching
that variable to the timeline and specifying its possible values is the
job of set_variables. This is most easily explained by using
an example, as shown below.
# create a template from which a series of trials can be built template <- trial_html_button_response(stimulus = insert_variable("animal")) # create a timeline with three trials, all using the same template # but with a different value for the "animal" variable timeline <- build_timeline(template) %>% set_variables(animal = c("cat", "dog", "pig"))