trial_survey_likert function is used to display a
survey page with one or more items with Likert scale responses.
trial_survey_likert( questions, preamble = "", scale_width = NULL, randomize_question_order = FALSE, button_label = "Continue", post_trial_gap = 0, on_finish = NULL, on_load = NULL, data = NULL )
A question or list of questions
Text to appear above the questions
Width of the scale in pixels (NULL is the display width)
Should order be randomised?
Text for the continue button
The gap in milliseconds between the current trial and the next trial. If NULL, there will be no gap.
An object containing additional data to store for the trial
Functions with a
trial_ prefix always return a "trial" object.
A trial object is simply a list containing the input arguments, with
NULL elements removed. Logical values in the input (
FALSE) are transformed to character vectors
and are specified to be objects of class "json", ensuring that they will be
trial_survey_likert function creates a trial that displays
a set of questions with Likert scale responses.
There are five arguments that are relevant to the survey itself:
The main argument is
questions, which can and can either consist of a single
question object generated b y
question_likert or a list of such objects.
The Likert scale items are laid out on an ordered scale with radio buttons
spaced at equal intervals, whose labels are specified when calling
the documentation for the question function for details of what this entails.
preamble argument is used to specify introductory text that appears
about the survey page. It accepts HTML markup and so can be used quite flexibly.
scale_width parameter controls the horizontal width of the Likert
scale, in pixels. By default, this is set to 100% of the width of the jsPsych container
(which may not be 100% of the screen width).
randomize_question_order argument is a logical value that
indicates whether or not the survey items should appear in a random order.
button_label specifies text to appear on the button displayed
at the bottom of the page, and which the participant must click before moving
on to the next trial.
Like all functions in the
trial_ family it contains four additional
post_trial_gap argument is a numeric value specifying the
length of the pause between the current trial ending and the next one
beginning. This parameter overrides any default values defined using the
build_experiment function, and a blank screen is displayed
during this gap period.
on_finish arguments can be used to
fn_ family of functions supplies a variety of functions that may
be useful in many cases.
data argument can be used to insert custom data values into
the jsPsych data storage for this trial
When this function is called from R it returns the trial object that will
later be inserted into the experiment when
is called. However, when the trial runs as part of the experiment it returns
values that are recorded in the jsPsych data store and eventually form part
of the data set for the experiment.
The data recorded by this trial is as follows:
responses value is a
an array containing all selected choices in JSON format for each question. The
encoded object will have a separate variable for the response to each question,
with the first question in the trial being recorded in Q0, the second in Q1, and
so on. The responses are recorded as the name of the option label. If the
name parameter is defined for the question, then the response will use
the value of
name as the key for the response in the responses object.
rt value is the response time in milliseconds for the subject to make
a response. The time is measured from when the questions first appear on the
screen until the subject's response.
question_order value is a string in JSON format containing an array
with the order of questions. For example [2,0,1] would indicate that the first
question was trial.questions (the third item in the questions parameter), the
second question was trial.questions, and the final question was trial.questions.
In addition, it records default variables that are recorded by all trials:
trial_type is a string that records the name of the plugin used to run the trial.
trial_index is a number that records the index of the current trial across the whole experiment.
time_elapsed counts the number of milliseconds since the start of the experiment when the trial ended.
internal_node_id is a string identifier for the current "node" in the timeline.