R/trial_html_slider_response.R
trial_html_slider_response.Rd
The trial_html_slider_response
function is used to display
an HTML stimulus and collect a response using a slider bar.
trial_html_slider_response( stimulus, labels = c("0%", "25%", "50%", "75%", "100%"), button_label = "Continue", min = 0, max = 100, start = 50, step = 1, slider_width = NULL, require_movement = FALSE, prompt = NULL, stimulus_duration = NULL, trial_duration = NULL, response_ends_trial = TRUE, post_trial_gap = 0, on_finish = NULL, on_load = NULL, data = NULL )
stimulus | The HTML content to be displayed. |
---|---|
labels | Labels displayed at equidistant locations on the slider. |
button_label | Label placed on the "continue" button |
min | Minimum value of the slider |
max | Maximum value of the slider |
start | Initial value of the slider |
step | Step size of the slider |
slider_width | Horizontal width of the slider (defaults to display width) |
require_movement | Does the user need to move the slider before clicking the continue button? |
prompt | A string (may contain HTML) that will be displayed below the stimulus, intended as a reminder about the actions to take (e.g., which key to press). |
stimulus_duration | How long to show the stimulus, in milliseconds. If NULL, then the stimulus will be shown until the subject makes a response |
trial_duration | How long to wait for a response before ending trial in milliseconds. If NULL, the trial will wait indefinitely. If no response is made before the deadline is reached, the response will be recorded as NULL. |
response_ends_trial | If TRUE, then the trial will end when a response is made (or the trial_duration expires). If FALSE, the trial continues until the deadline expires. |
post_trial_gap | The gap in milliseconds between the current trial and the next trial. If NULL, there will be no gap. |
on_finish | A javascript callback function to execute when the trial finishes |
on_load | A javascript callback function to execute when the trial begins, before any loading has occurred |
data | 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 (TRUE
and
FALSE
) are transformed to character vectors "true"
and "false"
and are specified to be objects of class "json", ensuring that they will be
written to file as the javascript logicals, true
and false
.
The trial_html_slider_response
function belongs to the "stimulus-response"
family of trials, all of which display a stimulus of a particular type (image,
audio, video or HTML) and collect responses using a particular mechanism
(button, keyboard or slider).
This one displays HTML and records responses generated with a slider.
The stimulus
argument is a string specifying the text to be displayed
as the stimulus. It can include HTML markup, meaning that it can be used to
any stimulus that can be specified using HTML. It remains on screen for a
length of time corresponding to the stimulus_duration
parameter in
milliseconds (or indefinitely if the parameter is NULL
).
Participant responses for this trial type are collected using a slider bar that the participant can move using the mouse. Once the participant is happy with this positioning they can click a button at the bottom of the page to move on to the next trial. This response method can be customised in several ways depending on the following arguments:
The min
and max
arguments are numeric values that specify the
minimum value (leftmost point on the slider) and the maximum value (rightmost point
on the slider) that a participant can respond with.
The start
parameter is a numeric value that indicates where the value
of the the slider is initially position. By default this is set to the middle of
the scale, but there are many cases where it may be sensible to have the slider
bar start at one end of the scale.
The movement of the slider is discretised, and the granularity of this
movement can be customised using the step
parameter. This should be a
numeric value that specifies the smallest possible increment that the participant
can move the slider in either direction.
The text labels displayed below the slider bar can also be customised by
specifying the labels
parameter. This argument should be a character vector
that contains the labels to be displaed. Labels will be displayed at equally spaced
intervals along the slider, though it is possible to include blank labels to create
the impression of unequal spacing if that is required.
The slider_width
controls the horizontal width of the slider bar:
the default value of NULL
creates a slider that occupies 100% of the width of
the jsPsych display. Note that this may not be 100% of the screen width.
To ensure that participants do engage with the slider, it is possible to set
require_movement = TRUE
which forces the participant to move the slider
at least once in order to be permitted to move onto the next trial.
The button_label
argument specifies the text displayed on the button that
participants click to move to the next trial.
As is the case for most trial_
functions there is a prompt
argument,
a string that specifies additional text that is displayed on screen during the
trial. The value of prompt
can contain HTML markup, allowing it to be
used quite flexibly if needed.
Depending on parameter settings, the trial can end when the subject responds
(response_ends_trial = TRUE
), or after a fixed amount of time
(specified using the trial_duration
argument) has elapsed. The length
of time that the stimulus remains visible can also be customized using the
(stimulus_duration
) argument.
Like all functions in the trial_
family it contains four additional
arguments:
The 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.
The on_load
and on_finish
arguments can be used to
specify javascript functions that will execute before the trial begins or
after it ends. The javascript code can be written manually and inserted *as*
javascript by using the insert_javascript
function. However,
the fn_
family of functions supplies a variety of functions that may
be useful in many cases.
The 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 build_experiment
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:
The rt
value is the response time in milliseconds taken for the
user to make a response. The time is measured from when the stimulus first
appears on the screen until the response.
The response
is the numeric value of the slider bar.
The stimulus
variable records the HTML content that was
displayed on this trial.
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.
Within the "stimulus-response" family of trials, there are four types of
stimuli (image, audio, video and HTML) and three types of response options
(button, keyboard, slider). The corresponding functions are
trial_image_button_response
,
trial_image_keyboard_response
,
trial_image_slider_response
,
trial_audio_button_response
,
trial_audio_keyboard_response
,
trial_audio_slider_response
,
trial_video_button_response
,
trial_video_keyboard_response
,
trial_video_slider_response
,
trial_html_button_response
,
trial_html_keyboard_response
and
trial_html_slider_response
.