TRATAM IENTOS Y NORM AS URBANÍSTICAS

There have been many methods for examining Working Memory in the past. Some of the more respected methods were examined in Chapter 3 in order to provide a basis for a new and improved suite of tests. Both traditional paper based tests and computerised tests were examined along with the advantages and disadvantages inherent in each. Through the study of these tests and using Baddeley’s model of Working Memory [Baddeley & Hitch, 1974], [Baddeley, 2000] as a basis, the structure of the VAM application began to take shape.

In this section, the design goals of the VAM application will be discussed in detail. Before this discussion though, a summary is provided:

1. The VAM is designed to examine both audio and visual Working Memory.

2. The VAM is designed to have a homogeneous structure in order to make it easy to use and to assist in the analysis of results.

3. The VAM is extensively configurable so that it can be used in a variety of different research areas and by a variety of different people.

4. The VAM is designed to be carried out independently so that multiple candidates can be examined simultaneously without the need for one-to-one administration.

When deciding on the structure for the VAM application, one of the most important requirements was that it could be used to explore both audio and visual Working Memory. In order to achieve this, the application needed to be broken down into several subsections, each one focusing on a different aspect of Working Memory. Although the VAM application was to be composed of several different tests, it was decided that the application should still have a homogeneous feel so as not to confuse new candidates. It was also decided that the more closely linked the tests were, the easier it would be to look for connections within the results they generated. With this

in mind, a format was required that could stimulate different aspects of the

candidates audio and visual Working Memory but still have the candidate respond in a similar manner regardless of what form the stimulus takes.

As peer-reviewed, scientifically tested, computer based Working Memory tests are still comparatively scarce, it was decided that the application should not require much in the way of computer skills to complete. It should look simple and be intuitive to use. After examining several existing computer and paper based tests of Working Memory, it seemed beneficial to use a well-recognised form of test as a starting point for the application – the standard digit span test.

The digit span test was a solid starting point for the application. The stimuli could easily be presented in audio or visual format and the candidate only required the abilities to see, hear, read and use a computer mouse in order to complete the tests. However, while it was a good starting point, it was clear there were still many issues to overcome in order to set this application apart from other Working Memory tests. The first and most important of these was that the use of digits alone would focus too much on the phonological aspects of Working Memory only.

As described in Chapter 2, in Baddeley's model of Working Memory, audio information is handled by the phonological loop. As a result of developing in a verbal language driven society, Baddeley theorises that the phonological loop may play a more active role in the rehearsal of Working Memory than its visual

counterpart, the visuospatial sketchpad [Baddeley, 2002]. Because of this, there is a tendency for people to 'hear' numbers in their head, regardless of whether they are presented in an audio or visual format.

In order to balance this effect, it was decided that a more visual form of stimulus should be used in conjunction with the digit span test. In this case, it was decided to use simple images as well as digits as stimuli. By creating an audio and visual image span test as well as an audio and visual digit span test, the focus on visual memory could be somewhat restored within the limits of the interface.

The basis for the image span test is exactly the same as the digit span test. The candidate is presented with a sequence of pictures or a sequence of words relating to the pictures which they must then store, process and re-enter into the system. While several types of images were tried out, in the end it was decided to use photographs of simple, recognisable objects. The reason for this is two-fold. Firstly, the objects must have simple and easily understood names or labels that can be used in the audio portion of the application and secondly, the objects need to be recognised and stored quickly by the candidate before the next item in the sequence appears. The more complicated the object in question, the less likely a candidate is to identify and store it in time. With the audio and visual image test used to balance out the audio and visual digit span test, there was a solid basis for an examination of the audio and visual components of Working Memory.

The interaction between the audio and visual components of Working Memory makes testing them separately difficult. Studies have shown that when possible people tend to phonologically recode or reinforce visually presented information, allowing subvocalization to aid in the rehearsal process. The reverse process also occurs with visual storage being used as a backup for audio information. Words that are easy to visualise are simpler to remember than abstract concepts. For instance a child might find it easier to remember a poem about a dog than one about happiness. This is known as the dual-coding hypothesis [Paivio, 1969, 1971]. In Baddeley’s model of Working Memory, this blending and additional storage of information is thought to take place in the episodic buffer [Baddeley, 2000, 2007].

When considering methods of measuring visual Working Memory, it was decided against using methods to artificially inhibit the phonological and visual

reinforcement of items. Although there has been success in the past with test items that cannot be readily verbalised such as wallpaper patterns [Broadbent & Broadbent, 1981] or unfamiliar Chinese ideograms [Wolford & Hollingsworth, 1974], it was felt that these measures would interfere with the real-world uses of the VAM application. It would also make the audio test of images extremely difficult since unrelated labels would have to be used for the images. By allowing the candidate to store information

as they would in the everyday life, the VAM can be of more use to areas like e- learning which is discussed in Chapter 8.

If necessary, the process of dual-coding can be disrupted through the use of distractor techniques. While not directly built into the application, these simple techniques can be used if the VAM is included in studies that require isolating certain aspects of Working Memory. Phonological recoding and rehearsal can be prevented through the use of articulatory suppression during the stimulus phase of the visually presented tests. Articulatory suppression involves the subject having to repeat a word or words under their breath thus preventing them from subvocalizing elements in the test [Baddeley et al, 1984], [Alloway, Kerr, Langheinrich, 2010]. This allows a more independent measure of visual Working Memory capacity, though studies have shown that this capacity is very limited [Sperling, 1960], [Cowan, 2001], [Vogel et al, 2001]. Similarly, visual recoding can be prevented through distracting the candidate with a random varying image such as a moving computer screen saver during the stimulus phase of the audio presented tests [Quinn & McConnell, 1996]. This in turn would allow a more independent measure of audio Working Memory capacity.

In order to be a true measure of Working Memory, an additional processing element also needed to be included in the tests. This allows the application to examine not only the phonological loop and visuospatial sketchpad, but also the central executive and the episodic buffer, thus exploring all the components of Baddeley’s model. As described in Chapter 2, the central executive is mainly responsible for focusing attention and manipulating information and the episodic buffer is responsible for storing and combining additional information [Baddeley, 2000].

In order to test these components, an extra function was built into the VAM

application. When re-entering a sequence presented by the test, the candidate must re-enter it in reverse order. In other words, if presented with the sequence 8, 5, 2 he/she must re-enter 2, 5, 8. This additional element places a lot more strain on the candidate’s Working Memory and by doing so, helps explore the abilities of the central executive and episodic buffer. In order to emphasise the configurable nature

of the application, it was also decided that this option could be switched on or off by the administrator as desired.

The configurable nature of the VAM application was kept in mind throughout its development. Ideally the VAM should be usable in as many varied fields as possible. As discussed in Chapter 3, many current tests of Working Memory have set

instructions for how they are to be administered. These instructions lay out

everything from the exact stimulus sequences used and the difficulty level involved, to the presentation time of the stimulus and the number of attempts the candidate gets. While there may be some leeway in this process when it comes to traditional testing methods (depending on the administrator), many computer applications are, by nature, more fixed in their administration. The VAM application was designed to be more flexible in its design. An extra administrator’s level was added to the VAM application to allow the settings used in each of the tests to be altered as needed. The options included in this level are discussed in more detail later on.

The need for multiple tests also brought up another issue of configurability, how would the VAM accommodate future modifications? To deal with this, it was decided to keep each aspect of the VAM self-contained. This approach allows future versions of the VAM to introduce new features and tests or alter old ones without disrupting the overall flow or requiring a major redesign of the application.

By designing and implementing each component test in the VAM to be fully self- contained and functionally separate from the others, it meant that individual tests could be switched on or off with little effort or overall effect on the application. This proved to be a great asset during the initial debugging and testing of the application. It will also prove to be beneficial to future iterations of the VAM application by allowing new tests to be easily added or removed. The flowchart based nature of Authorware, the design platform in which the VAM was implemented, helped a lot with this process. The nature of Authorware and the implementation of the VAM will be discussed in more detail later in this chapter.

A common element of many of the testing methods described in Chapter 3 is the requirement of an administrator to oversee the testing process. While there are some advantages to this approach, it does require an extra investment of time and

resources when using them in large studies. The VAM application was designed to be used independently. Administrators can still monitor candidates on a one-to-one basis if required, but they are not forced to. A candidate can complete the VAM application without any external guidance. The VAM application provides the necessary instructions, monitors the responses and collates this data into a detailed results file automatically. A candidate can even use the VAM in his/her own home and simply send the results to the administrator when done. This saves both parties considerable time and effort and allows the VAM to be used in an even wider range of studies.

It is this combination of features that allows the VAM application to provide a unique contribution to the field of exploring Working Memory; one that will prove useful in a number of diverse fields. The next section discusses how this model was expanded and implemented to form the final application.