ca.yorku.cse.mack.tilttarget

Class TiltTargetActivity

java.lang.Object

Activity

ca.yorku.cse.mack.tilttarget.TiltTargetActivity

public class TiltTargetActivity
extends Activity

TiltTarget

Summary

• Experiment software to investigate device tilt as a target selection method

Related References

The following publication presents research where this software was used.

• Exploring tilt-based text input for mobile devices with teenagers, by Fitton, MacKenzie, Read, and Horton (BHCI 2013).

• The study of extraneous conditions that affect tilt-based pointer movement, by Serackis, Miniotas, Katkevičius, Krukonis, and Plonis (BIOMDLORE 2016).

Setup Parameters

The application launches with a setup dialog: (click to enlarge)

In all, there are 14 setup parameters, organized in 12 spinners and two checkboxes. The setup parameters are explained as follows.

Parameter	Description
Participant Code	A code to identify the user being tested. In experimental research, a user is typically called a "participant".
Session Code	A code to identify the session. This code could be used in an a longitudinal experiment, where participants are tested over multiple sessions. Each session might involve an hour of testing, with one session per day over multiple days.
Block Code	Note: There is an inactive setup parameter for "Block code". The block code is generated automatically by the software.
Group Code	A code to identify the group. If the experiment uses a within-subjects design, participants are usually assigned to groups. This code identifies the group. This procedure is known as counterbalancing, which is used to offset order effects. (See section 5.11 in the course's Suggested Readings for complete details.)
Condition Code	A code to identify an external condition. This setup item is an editable text field. Tap to popup an input method editor to change the value. The condition code is useful if the experiment included an independent variable pertaining to an environmental condition or a context of use. As an example, an experiment might include "mobility" as an independent variable with levels "sitting" and "walking". The code "Sitting" might be used for the sitting condition and the code "Walking" for the walking condition. These codes appear in the output data to facilitate analyses. BTW, an example of an experiment using this independent variable is described by Fitton et al. in Exploring Tilt-Based Text Input For Mobile Devices With Teenagers.
Sequences per Block	The number of selection sequences for each block of testing.
Targets per Sequence	The number of targets to select for each sequence. Targets appears as highlighted keys. Each target to select is chosen at random from the available targets.
Keyboard	The keyboard to use. The following options appear: 3x5 - a portrait arrangement of 15 keys, somewhat like a phone keypad 4x10 - a landscape arrangement of 40 keys, somewhat like a qwerty keyboard
Order of Control	The options are Velocity – tilting the device controls the velocity of the virtual ball Position – tilting the device controls the position of the virtual ball
Tilt Gain	A value from the set { Very low, Low, Medium, High, Very high } roughly corresponding to gain sensitivities ranging for very low to very high.
Dwell time	A value from the set { 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 }. The value sets the duration in milliseconds that the ball must remain inside a key to select the key
Sensor sampling rate	A value from the set { Normal, UI, Game, Fastest } to set the sampling rate for the device sensor. See Demo_Sensors for further details.
Vibrotactile feedback	A checkbox item. If selected, enables a vibrotactile pulse to be emitted on each key selection
Auditory feedback	A checkbox item. If selected, enables an auditory click to be emitted on each key selection

Program Operation

After the setup parameters are chosen, the program is launched by clicking the OK button. The following screen appears:

To begin selecting targets, the virtual ball must be positioned in the green square for one second. When this occurs, the program transitions to an experiment screen featuring the selected arrangement of targets. Figures appear below for the 5x3 (left) and 4x10 (right) arrangements.

The user selects targets by tilting the device to position the ball on a target and then maintaining the ball inside the target for the chosen dwell time. If the ball is inside the wrong target, a selection still occurs, but is logged as an error. After the specified number of selections, results appears:

Testing is organized as trials per sequence and sequences per block. At the end of a block, the application terminates.

Data Storage

Data are also saved in files for follow-up analyses. There are two files, an "sd1" file which contains data on a per-selection basis (timestamps + keys), and an "sd2" file which contains summary data for each sequence of input. The data files are saved in the public directory on Android devices in a sub-directory called "TiltTargetData". Below are example files:

• sd1 – TiltTarget-P00-5x3-S00-B01-G00-C00-POS-TG40-DT500.sd1
• sd2 – TiltTarget-P00-5x3-S00-B01-G00-C00-POS-TG40-DT500.sd2

The data in the sd2 files are comma-delimited to facilitate importing into Excel or a statistics application for follow-up analyses. An example is shown below for the data in the sd2 file above.

Author:

Scott MacKenzie, 2011-2025

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	TiltTargetActivity.ScreenRefreshTimer

Constructor Summary

Constructors

Constructor and Description
TiltTargetActivity()

Method Summary

Modifier and Type	Method and Description
void	doEndOfSequence()
void	doNewSequence()
int	getDefaultDeviceOrientation()
protected float[]	lowPass(float[] input, float[] output, float alpha)
void	onAccuracyChanged(Sensor sensor, int accuracy)
void	onCreate(Bundle savedInstanceState)
protected void	onPause()
protected void	onResume()
void	onSensorChanged(SensorEvent se)
void	onStop()
void	onWindowFocusChanged(boolean hasFocus)
void	pickNextTargetKey()
void	updateProgressText()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TiltTargetActivity

public TiltTargetActivity()

Method Detail

onCreate

public void onCreate(Bundle savedInstanceState)

onWindowFocusChanged

public void onWindowFocusChanged(boolean hasFocus)

onResume

protected void onResume()

onPause

protected void onPause()

onStop

public void onStop()

onAccuracyChanged

public void onAccuracyChanged(Sensor sensor,
                              int accuracy)

onSensorChanged

public void onSensorChanged(SensorEvent se)

getDefaultDeviceOrientation

public int getDefaultDeviceOrientation()

doEndOfSequence

public void doEndOfSequence()

doNewSequence

public void doNewSequence()

pickNextTargetKey

public void pickNextTargetKey()

updateProgressText

public void updateProgressText()

lowPass

protected float[] lowPass(float[] input,
                          float[] output,
                          float alpha)