Intendix

Key takeaways

Intendix belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Intendix to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Intendix from memory before moving on to harder problems.

Reference excerpt

intendiX (now known as Unicorn) is an EEG headset designed for use as a brain-computer interface (BCI). It was made available in 2009 by Guger Technologies, stylised as g.tec. It has been used for art pieces, to control components of a smart home, and as assistive technology.

Description intendiX can rely on P300 waves p and SSVEP. In a P300 BCI, different items on the monitor (such as letters) flash while the user is instructed to silently count each time a target item flashes. The BCI can identify the target item by determining which flashes elicited brain signals. BCIs that use steady state visual evoked potentials (SSVEPs) instead rely on items that flicker instead of flash. The user focuses on one of the flickering items, producing SSVEP activity at the same frequency as that item. Therefore, a BCI can determine the target item by identifying the peak frequencies in the user's visual areas, which can only correspond to one of the many items on the monitor.

intendiX components The intendiX system requires four components:

sensors that detect brain activity; signal processing algorithms that identify relevant brain signals in real time; a device or application where the output signal is sent; and an operating environment that connects these components to each other and mediate interaction with the user. (Wolpaw et al., 2002; Allison et al., 2007, 2012; Wolpaw and Wolpaw, 2012). Sensors: The first intendiX system, released in 2009, allowed users to work with either passive or active electrodes. While both of these electrodes require electrode gel, like conventional electrodes, the active electrodes do not require skin preparation and are more robust to external noise. This is because active electrodes feature amplifiers and other electronics within each electrode, whereas passive electrodes first send brain signals along cables before amplification. In 2010, g.tec introduced the Sahara dry electrode, which does not require gel. Signal processing: In typical BCIs, signal processing often involves different stages. For example, spatial filtering algorithms will determine how to best utilize information from the different electrodes, and pattern classification may categorize the resulting data. The intendiX system uses different signal processing algorithms for different types of brain signals. With P300 signals, intendiX relies on stepwise linear discriminant analysis (SWLDA), The more general approach, LDA, is used in other types of BCIs as well. With SSVEP activity, intendiX instead relies on bandpower at different frequencies. A simple SSVEP BCI might present two stimuli on a monitor; the left stimulus oscillates at 8 Hz and the right at 13 Hz. If the user's visual areas show an increase at 8 Hz and its harmonics, a signal processing algorithm can identify this spike and thus infer that the user is focusing on the left stimulus. Device/Application: Initially, intendiX was used to control a speller. Using the extendiX system, users can also control any smart home device such as a television, music player, air conditioner, or light. extendiX can control other devices as well, such as mobile robots or games. extendiX receives commands from intendiX via UDP and could thereby control any external device. In March 2012, g.tec presented the pre-release of their new Screen Overlay Control Interface (SOCI) at the CeBIT exposition in Hannover, Germany. Visitors to the g.tec booth could use the intendiX system to play World of Warcraft and Angry Birds, and additional game interfaces are being developed. The SOCI will be publicly available later in 2012. Operating Environment: The intendiX system interacts with users in different ways, depending on whether it is a P300 or SSVEP BCI. Both approaches require paying attention to different regions of the monitor to produce distinct brain signals that the BCI can recognize. intendiX also includes software to determine when users are not paying attention based on their EEG signals. This way, the system can easily enter a "sleep" mode without any instruction from the user, and return to an active state when the user again begins paying attention to the activity on the monitor.

Worked examples

Example 1 — a first encounter with Intendix

Start with the simplest possible case. Write down what Intendix claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Intendix before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Intendix ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Intendix

In research: Intendix appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Intendix in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Intendix is common in secondary-school and first-year university syllabi. It links to neighbouring topics Brain–computer interface, so understanding it makes those chapters shorter.
In everyday life: Look for Intendix outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Intendix in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Intendix means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Intendix out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Intendix in simple terms?

intendiX (now known as Unicorn) is an EEG headset designed for use as a brain-computer interface (BCI). It was made available in 2009 by Guger Technologies, stylised as g.tec.

Why does Intendix matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Intendix?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Intendix.