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Blink detection and attention evaluation: the NeuroSky MindWave

Hardware for UX evaluation

As part of Project Sunflower, we took various approaches to interface evaluation. Alongside heuristic evaluation, walkthroughs and so forth, we also used various bits of hardware to support trials. This post describes setup and sample code for the NeuroSky MindWave, an inexpensive BCI (brain-computer interface – think ‘electroencephalogram’, or ‘brain wave monitoring’) that uses a single sensor placed on the forehead to measure eye blinks, ‘attention’ and ‘meditation’. These two latter variables shouldn’t be taken at (scuse the pun) face value; according to a report by Travis Ross, they’re based on a proprietary algorithm, with attention reported to relate to beta waves, hence linked to wakefulness/focus, and meditation linked to alpha waves – level of calm. Vague, admittedly, but then these devices are priced for and in large part targeted at the consumer market. If you’ve ever seen those Mattel Jedi force-trainer toys, those are based around the same technology.


Having installed the software prerequisites and drivers, the next thing is to run the Thinkgear Connector. This is an extremely helpful little piece of kit, which listens to the USB radio link and makes the sensor data available to applications. This reduces the connection step to a couple of lines of code. Since the Thinkgear Connector will return JSON upon request, the data packets are easy to parse.


import sys
import json
import time
from telnetlib import Telnet


# app registration step (in this instance unnecessary)
# tn.write('{"appName": "Example", "appKey": "9f54141b4b4c567c558d3a76cb8d715cbde03096"}');
tn.write('{"enableRawOutput": true, "format": "Json"}');

if len(sys.argv)>1:

# default values
eSenseDict={'attention':0, 'meditation':0};
waveDict={'lowGamma':0, 'highGamma':0, 'highAlpha':0, 'delta':0, 'highBeta':0, 'lowAlpha':0, 'lowBeta':0, 'theta':0};

while i

(Edit: The above code is truncated. See for full code)

Example output

The code as written above produces very simple CSV output, which has the benefit of being very easy to plot using something like Gnuplot:

plot "test-output.log" using 1:3 with lines, "" using 1:4 with lines, "" using 1:5 with lines

Graph of three variables: working on a language problem.

Some sensor data captured: subject was working on a language problem. Red

Sensor data. Activity: Watching TV

Sensor data captured: individual was watching TV. Red

Note: the number of blinks captured is low enough that the chances are that the MindWave is not picking up all blink events.

OPDS: building an ebook catalogue

This is part of a series wrapping up (belatedly, alas) the findings from Project Sunflower. As the protagonists of the Project have moved on to pastures new, leaving their notes behind, editorial duty has fallen to yours truly.

In this post, we look at OPDS, otherwise known as ‘Open Publication Distribution System’, and why it’s worth a look for anybody intending to integrate ebook platforms into the student experience. For anybody who’d rather skip ahead, version 1.1 of the standard can be found right here.

OPDS is, according to the specification, designed as

a syndication format for electronic publications based on Atom and HTTP

and can

enable the aggregation, distribution, discovery, and acquisition of electronic publications


existing or emergent open standards and conventions, with a priority on simplicity.

Now, as we will see from reviewing the performance of typical embedded ebook search/indexing functions and interfaces, most ebook readers aren’t designed to contain huge numbers of ebooks. At 7.99 an ebook, most readers will be cautious in their acquisitions, so perhaps the perception from some manufacturers is that it is pointless to create readers that specialise in navigating across hundreds of thousands of files. Many portable media devices suffer from similar difficulties – the classic ‘clickwheel’ interface on iPods, as applied to a large number of files, became the subject of a 2009 satirical report by The Onion.

The relevance of OPDS is the following: OPDS allows you to search and browse across extensive collections of documents. They don’t need to be books; an OPDS frontend on an institutional repository is perfectly achievable, format conversion notwithstanding. The obvious use case is searching or browsing for a single file, but part of the relevance of OPDS is the fact that it also allows for batch mode: a student downloading the full reading list for the semester, for example. Wouldn’t that be convenient?

An OPDS catalogue is fairly straightforward to set up. For prototyping purposes, the well-known ebook software Calibre can be used to experiment with the concept; it can be found in the Calibre software under Preferences->Network->Sharing over the net, and is referred to as a ‘Content Server’. If you’d rather experiment with a static OPDS catalogue — providing no search function, but with browse functions that make full use of your metadata — consider trying calibre2opds, a Java application that renders your Calibre catalogue as a set of static HTML pages and, being simpler and more secure (by dint of having very few moving parts), may be considered a relatively secure way of deploying a prototype. A comparison of these alternatives may be found here.

Cross-platform compatibility: Limited.

Android and the iPad approach this on a per-application basis, and a good implementation is available for both. iBooks won’t handle the catalogue functionality, but you can manually type the address into Safari; then, when you click on an ePub file, iBooks can handle the download. Alternatively, you can use Stanza, which works well – but when iOS 5 came out, we discovered that Stanza ceased to work until we updated the iPad to the latest version, so be prepared for sudden failures around the time of iOS upgrades.

The Kindle is able to use OPDS catalogues, but requires them to run on port 80 (the usual port for a web server, admittedly, but not Calibre’s preferred choice for practical reasons). Simpler e-Ink devices mostly still do not have any mechanism for connecting to the Web, and therefore this sort of functionality is not available on the platform itself, so desktop software must be used instead.

Ease of setup: Moderate.

Getting a Calibre content-server running on a home network is relatively easy provided that the user is familiar with terms like ‘IP address’. However, practical implementation on a larger scale requires significantly more thought; not only are there security and sustainability issues around the software, but the usability of the resulting catalogue is very dependent on good metadata.


Standard, relatively simple to set up, and extremely liberating – a convenient distribution channel, bypassing the need to centralise via a commercial vendor, what’s not to like?


Support for OPDS is patchy and the standard is still relatively recent. Many popular ebook reader applications do not support it explicitly. Fortunately, it’s so near to popular standards that all you really need is a web browser and an ebook reader to get some benefit from an OPDS.

Sample screenshots

Browse by tag screenshot

Browsing the Calibre content server by tag


Browse by author screenshot

Browse by author

Project Sunflower: Evaluation Based on Neilsen’s Heuristics

Jakob Neilsen has devised ten general usability heuristics that help evaluate user interface design. Further to our usability research, these guidelines have been used to compare the user interface design of the iPad, Kindle and XOOM. The heuristics given by Neilsen are:

Visibility of System Status – The user should be informed of what is going on

Match between System and Real World – The system’s language should be familiar and follow real-world conventions

User Control and Freedom – System should support undo and redo to help user leave an unwanted state

Consistency and Standards – The meaning of words and actions should stay consistent in  different situations

Error Prevention – Eliminate error-prone conditions or allow users to perform commit actions

Recognition rather than Recall – The user should be able to recognize the meaning of actions than having to recall their functions

Flexibility and Efficiency of Use – System should provide certain accelerators that help speed up interaction for expert users, however it should cater to both, novice and expert users efficiently

Aesthetic and Minimalistic Design – The design should be aesthetic, minimalistic and easy to understand

Help Users Recognize, diagnose and recover from errors – The system should assist users in recognizing, diagnosing and recovering from errors

Help and Documentation – Adequate help and documentation should be available to the user when needed

The study has been conducted based on user interaction with the eBook reading interface.

Results of the Analysis

The table shows the results obtained. It displays the areas where the devices do not agree with Neilsen’s Heuristics, and mentions the reason it does not fit the respective guideline(s).

Usability Heuristics iPad Kindle DX XOOM
Visibility of System Status No Feedback on Downloads Download Progress bar not clearly visible
Match Between System and Real World Dynamically Changing Page Numbers and Location Shown in Percentages Locations Interpretation Needs to be Learnt Dynamically Changing Page Numbers and Location Shown in Percentages
User Control and Freedom No Forward Button No Forward Button No Forward Button
Consistency and Standards
Error Prevention No ‘Commit’ actions Accidental ‘Back’ due to Slow Response Rate System Crashes
Recognition rather than Recall Use of Applications needs to be learnt Button functions need to be learnt Use of Applications and buttons needs to be learnt
Flexibility and Efficiency of Use Accelerators absent Accelerators absent Accelerators absent
Aesthetic and Minimalistic Design
Help Users Recognize, Diagnose and Recover from Errors No suggestions for crashes
Help and Documentation None provided on-device None provided on-device

This study further agrees with our previously done research indicating that the current eBook readers have some shortcomings that affect the user experience and there is more room for improvement that would lead to more satisfying user interaction with the device from an eBook reading perspective.

Project Sunflower: XOOM Usability Study

The Motorola XOOM is the first tablet to run on Android 3.0. It supports 720p recording and boasts an Nvidia Tegra 2 1GHz processor. The XOOM was introduced as a tablet that does a lot of things, one of which is eBook reading. Our aim was to study the eBook reading capabilities of the device. We studied the reading experience, the device itself and the UI the device had to offer from a purely eBook reading perspective.


The first thing noticeable about the device, or should I say not noticeable, was the power button. The power button was nowhere to be seen on the sides of the device. Users often mistook the SIM card slot for the power button. This was an issue with all users. The power button is on the back of the device, besides the camera. It isn’t easily identifiable.

The XOOM weighs 1.6 lbs, slightly more than iPad and Kindle that weigh at 1.3 lbs and 1.2 lbs respectively. This was another concern shown by users. The users pointed out that the impact of the weight was clearly evident through stress in the wrists when holding the device.

The thickness of the device is also not comparable to the iPad 2 and Kindle DX, the two other devices used for the study. The users thought a thinner device would be more convenient. The greater thickness however, did provide for slightly better grip.

The keyboard feels too broad when holding the device in landscape mode making it difficult to type.

User Interface

The users liked the eBook reading experience the app had to offer. The pages were displayed across the entire screen not wasting space at the edges and thus displaying more words per page in portrait mode. Settings provided by the app were also deemed adequate by users.

The most admired feature was ”Night mode’. This feature allows users to change the screen to white on black from black on white. This makes it more comfortable to read in low-lighting conditions and especially at night. This feature is an advantage because the backlit display can cause severe stress to the eyes when reading continuously for a long time.

The areas users generally found tricky were finding applications to read books on the device. Previous experience with the device played a significant role in this case. The users with little or no experience found it difficult to find and install apps. Most users wanted the app to be installed by default instead of requiring the user to install it.

The landscape view does not support 2-page display, causing almost 2 inches of screen space being wasted on either sides of the screen. This space could be better utilized to display more text and thus help users to see more information on the same screen.

The most severe issue was that of crashes. In case of some users, the app crashed abruptly and the user was taken back to the homescreen.


The Motorola XOOM is a powerful device and runs the latest Android 3.0 OS, however as far as eBook reading goes, is not a very suitable option. Especially for academic text. The device’s weight. thickness, abrupt crashes, and the ePub format’s illustrations rendering capabilities deems it unsuitable for reading academic text. Like most other tablets, the XOOM is good for leisure reading with its simple UI, various viewing modes and fast responsiveness. Academic text on the other hand requires more information displayed on a single page, the ability to flip through chunks of pages while being able to see the scrolled contents and the ability to make notes on the textbook. It will take more time till eBook readers support these features and as of now the Motorola XOOM does not seem ready for use as an academic textbook reader.

Project Sunflower: Kindle DX Usability Study

The Kindle DX is the only dedicated eBook reader from the devices we are using for the study. It has an E-Ink Pearl display and was made with the sole purpose of comfortable and convenient reading. The first generation Kindle had a big launch in 2007, where all the Kindles were sold out in five and a half hours. The Kindle stayed out of stock for five months. These figures tell a lot about its popularity and people’s interest in reading on the device.

We studied the Kindle from point of view of academic text. We studied the reading experience on Kindle DX, the user interface it offers, and the device in general.


The users were really happy about the fact that it was lighter than any other tablet they had held in their hands.  The fact that it is lighter than most other devices is true, however saying its weight makes it an ideal eBook reader is not. The users did have problems with the weight of the Kindle DX. Some users that had used other Kindles previously said that the bigger screen on the  DX was a great advantage, but the addition to the weight worked against that. The users were comfortable using the smaller Kindle than buy the more costly, heavier Kindle DX for a bigger screen.

The E – Ink Pearl display made a mark on all users. The users were very impressed with the fact that there was no glare from the screen, and the absence of brightness adjustments to be made to the screen to adapt to ambient light.  The screen was perfectly readable in varying lighting conditions. The screen felt good, and mimicked paper.

The problems mostly faced were with the buttons on the device. Users complained the keys on the keypad were too small, and found holding the device and typing at the same time uncomfortable as the keypad was too low on the device. The fact that there are no dedicated numeric keys added to this factor. The 5-way stick was difficult to identify for the first time, and making selections was difficult until the users realized the 5-way stick could be pressed in to make a selection. The device has navigation buttons on the right side only, which makes it mandatory for people to hold the device either in the right hand, or use another hand to flip pages when holing it in the left. The ‘Back’ button and the button to navigate through a book were misleading. Users mistook the ‘Back’ button for page navigation, however it is for navigating through and to menus and not for in-book navigation. Some users also expressed the need of a ‘Forward’ button as the slow response rate may cause repeated actions causing unwanted results. The Menu button was also misleading. as users thought they could change settings in-book using the Menu button. There is a dedicated key for settings on the keypad. This key too, is difficult to identify the first time.

User Interface

The users liked the simplicity of the UI, as all the books were displayed on the Homescreen. This made it very easy to find a required book on the device.

The Kindle offered a number of font sizes to aid the user. It also has a text-to-speech feature. That being said, the text-to-speech isn’t as advanced as one might expect. It is like any other text-to-speech software you may have tried using. The software  sounds fairly automated and loses expressions, which are key to any book or story alike.

The fact that it was not a touchscreen and did nothing but read eBooks was seen as an advantage. The lack of a touchscreen and other features caused less distractions to users and readers spent time reading instead of anything else.

The main concern shown by all users was the responsiveness of the UI. Common tasks like unlocking the device, opening a book and flipping a page took a long time due to the slow refresh rate. Talking from an academic texts viewpoint, fast refresh rate is one of the most important attributes an eBook reader should possess. When reading textbooks, most people flip through chunks of pages to retrieve relevant information. A task that seems impossible at a very slow refresh rate.


The Kindle is great for linear reading, but its currently not suitable to be used to read academic text. The refresh rate is too slow to allow for fast flipping to and from pages. The limited illustrations rendering capabilities and weight are also a problem. The Kindle, due to its low weight and E-Ink display may be really well suited for leisure reading, but it might take some time till one can use the Kindle DX to replace textbooks.


Project Sunflower: iPad Usability Study

The iPad since its launch has been promoted primarily as a web-surfing device. Its eBook reading capabilities came with applications that rendered eBooks on the iPad. Our usability study tested the iPad from an eBook reading point of view. More so, from the point of view of academic texts. We tested the eBook reading experience the iPad has to offer, the user interface of iBooks, the settings it allows the users to alter, and the device in general.


Most users were very happy with the design of the device, and particularly liked how thin it was. That being said, the flip side is that they were not very happy with the weight of the device (despite being 15% lighter than its predecessor), and complained that their hands would hurt after a certain amount of time when using the device to read. When reading from the device for a significantly long time, one starts to feel the edges, especially when held in one hand.

The most common concern that all participants raised was that they all wanted the iBooks app installed by default instead of having to install it separately to be able to read eBooks. I admit this isn’t a lot of work, but isn’t the whole point of eBook readers allowing the user to get access to books as fast as possible? Inexperienced users did not know much about applications and their installation.

The screen feels good to read, however exposing your eyes to an LED-backlit display for a really long time isn’t a good idea. Especially in low-lighting conditions.

User Interface

The users were particularly impressed with the responsiveness of the touchscreen. They liked the way the device registered the tap exactly where they intended, and did exactly what they wanted it to do.

Users that had previous experience using iOS devices were more comfortable operating the device than others that had never used iOS devices before.

iBooks renders the book in a very graphical way to make it look not like plain text, but more like an actual book. This feature, however, costs almost an inch of space from each side. Space that could be utilized to fit more content on a single page, allowing the user to read more on a single page, saving some time from the reduced page flips.


From a purely objective viewpoint, I’ll go ahead and say the iPad has a supercool UI and great responsiveness, however, when it comes to eBook reading, these features don’t really count. Its backlit LED display and weight make it a ‘not so ideal’ eBook reader when it comes to academic text. The device is useful for leisure reading, but it may take some more time before we see students using the iPads as textbooks leaving their 2000 page hardback textbooks at home. One of the main uses of a textbook is to refer to a particular formula, diagram or search a particular concept as soon as possible. The ePub format’s limited Math rendering capabilities coupled with the inability to write all over the book and flip through chunks of pages at a time does not affect leisure reading, but makes it not so suitable for academic use.

Project Sunflower: Usability Study

As part of our eBook usability study, this part deals with studying the devices from the eBook reader point of view. All three devices,  Apple iPad 2, Amazon Kindle DX and Motorola XOOM have eBook reading capabilities, with Kindle being a dedicated eBook reader.  The aim of the study was to analyse the ease with which a user can perform a particular task on each device, the user-friendliness of the UI and the eBook reading experience the device has to offer. Two studies were devised for the purpose of our research. One study aims at understanding the user experience the devices have to offer in general, and the second study aims at understanding the eBook reading experience.

Internet access was enabled for all devices for the purpose of the study, as connecting to the internet is not part of the eBook reading activity.

Study 1

The study was implemented in two phases, the difference being the instructions given to the user.

Phase 1

In this phase, the devices were connected to the internet, and the users were asked to download and open an eBook on the respective device. They were not told about specific apps that were needed to render eBooks, and were given no specifics whatsoever. The users were not given any instructions so as to get a firsthand view of where they try to get the eBooks from, whether they even know about the requirement of specific apps to render eBooks on the devices and of any other OS specific functions.

This study helped evaluate whether prior experience with the OS played a significant role in understanding OS specific requirements such as apps, the app stores the devices used, and the place to get eBooks from.

Phase 2

In this phase, the users were given more specific instructions about the applications that they would have to download to be able to read eBooks in the ePub format. This test helped answer questions such as, did the user know where to get the application, which application to get, did they have trouble installing the application, how to download eBooks on the device, and so on.

This study gave a very clear understanding about the intuitiveness of the UI, the difficulty or ease in performing tasks, and whether previous experience with either similar devices or the operating system played a part in performing the given task.

Study 2

This study was devised to evaluate the eBook reading experience each of the devices had to offer. The participants of the study gave feedback on the overall device design from point of view of an eBook reader, the user-friendliness of the user interface from the eBook reading point of view, and inputs on the in-book settings the devices allowed the users to change.

In this study, the users were asked to inspect two areas of the eBook reader or eBook reading app. First, the overall readability of eBooks was tested by asking the users to read a book for ten minutes on the device. The eBooks were rendered at default settings. This part of the test was to get feedback on the eBook reading experience the device offers. For the next part of the test, the users were asked to find and change the settings they wished to change when reading, and also inspect the settings the device offered. For this part of the study, each user was given five minutes. This dedicated time to change settings allowed the users to find all or most settings the software offered, and identify settings the software lacks or are unnecessary.

Cc image by Astragony

Project Sunflower: Time to Launch Application, Open a Book and Flip Page

Well, we now have results regarding the time taken for the Apple iPad 2, Amazon Kindle DX and Motorola XOOM to render eBooks. We installed iBooks on iPad and the Kindle App for Android on XOOM. The Google Books app can’t be installed (yet) in UK due to copyright issues. We recorded the time taken by the devices to open the app, open a book, and flip a page.

Since there is no emulator that performs exactly like the physical device, we chose to take a practical approach to measure the times. The render times were measured in two ways. One, manually, and the other using a video camera.

Manual Method

Take a stopwatch in one hand, and have the other hand tap on the device. For example, when using an iPad, what we did was to hold the stopwatch in the left hand, and tap the iPad with the right hand. Start the stopwatch precisely when the iPad is tapped, and stop when the desired action is done. This method depends a lot on the user’s reflexes and you may have your doubts about the level of precision when it comes to results. Let me tell you, the results were surprisingly accurate. Read the figures to see for yourself.

Camera Method

This is a slightly more sophisticated way of measuring, though just as simple. All you need to know is the fps (frames per second) at which the video is recorded, and a video player that can replay the video frame-per-frame. Record the desired action on-camera, and then replay the video frame-per-frame. The number of frames traversed from the start to end of the task gives a more precise time taken to complete the task than the manual method.


We measured the times for six free eBooks per device. Six readings were taken per task, and the average time for each task was calculated.

iPad (Average from six readings)

Kindle DX (Average from six readings)

There is no application load time as all the books are displayed directly on the Homescreen.

XOOM (Average from six readings)

Both the methods gave fairly similar results. The differences in the times on an average are:

The standard deviations for each method are shown below:

iPad (Standard Deviation)

Kindle DX (Standard Deviation)

XOOM (Standard Deviation)

The standard deviation tables show that the camera method showed less variation from the average as compared to the manual method in all but two cases, where the difference is only 1/100th of a second. These two cases may be safely ignored.

Although both methods gave fairly similar results, it must be noted that the manual method would give varied results for every test. It is completely dependent upon user reflexes, and slow reflexes could have seriously bad results. The camera method does take up more time, however the results are more accurate and dependable  So, I’d recommend the camera method.

All the recorded times are an average, and the times may change with the length of the books proportionally. These results give us a fair idea about the various devices when it comes to render speed and page flipping. The iPad and XOOM clearly render faster than Kindle DX. However, these results are only pertaining to the device capabilities and say nothing about the user experience. What makes an eBook reader good or bad does not depend only on the render speeds, but more so on the user experience the device has to offer. A detailed usability study of the devices will be undertaken soon which will shed light on the varied user experience, and help us better understand what the user expects from an eBook reader.