Test 1: Visual Memory Test (Letters)

The first test within the application is a visual based Working Memory test using letters as stimuli. Originally, numbers were used instead of letters as in the

traditional digit span tests. After further examination however, letters seem a better choice of stimulus. There are two main reasons for this:

Firstly, when generating a pseudo-random sequence of numbers, the potential pool from which these numbers can be drawn only ranges from 0-9. Letters, on the other hand carry a potential pool of up to twenty six items ranging from A-Z. Obviously, not all of these letters could be used in the final application as it would make the interface look far too crowded. However, by using letters as a basis instead of numbers, the number of different stimuli included in the test could be increased beyond ten.

Secondly, sequential runs of letters or numbers are easier to remember than random sequences. For example, the sequence 1, 2, 3, is simpler to remember then 5, 2, 9. This is simply because humans are used to hearing and seeing numbers and letters presented in order and so have those sequences chunked together in memory already. By using letters instead of digits, a majority of non-sequential letters can be chosen

for the final stimulus pool to minimise the risk of lengthy sequential runs.

The letters chosen to be in the stimulus pool for generating sequences in this test are all consonants and were picked from throughout the alphabet. The letters were chosen carefully to minimise the chance of accidentally creating words or phonetic sequences and thus aiding recall. The lack of vowels and the distribution of the letters helped avoid this. Even with a pool of 21 items to choose from though, it was extremely difficult to eliminate every connection between the items chosen. In the end, a pool was chosen that helped minimise these connections. The final letters chosen were C, D, F, H, K, L, N, Q, R, T, V and X.

The purpose of this first test is to examine how a candidate’s Working Memory responds when presented with a sequence of letters that he/she must store, process and reproduce. Before starting the test, there are two introductory screens containing instructions for the candidate. The first screen describes the layout of the test and explains what is required of the candidate. The second screen introduces the interface for re-entering the sequence and explains what each component does. When the candidate is satisfied that he/she understands the concept and functionality of the test, he/she presses the continue button and the test begins.

When the start button is clicked by the candidate, the first sequence of letters will be displayed on the screen in order (see Figure 3). Each letter will be displayed for a preordained length of time which can be controlled by the test administrator beforehand using the administration menus described below. The default display time is three quarters of a second.

Figure 3: Example sequence of letters generated by the VAM application. Each box represents a single screenshot.

When the sequence is finished, the candidate is immediately returned to the

application's interface screen and asked to re-enter the previously displayed sequence in either reverse or forward order depending on what mode the application is in. Once he/she has done this and is happy with the decision, he/she can click the continue button to move on to the next sequence. Meanwhile his/her performance is measured and stored by the application. If the candidate feels he/she has made a mistake while entering the sequence, he/she can reset the response field and try again; of course, doing so will add to his/her overall response time.

After each sequence, the application records the following information: The randomly generated sequence, the candidate entered sequence, the candidate's response time when entering the sequence and finally whether or not the candidate

Figure 4: Screenshot of the test interface for the visual memory test with letters component of the application.

The candidate must use the letter marked buttons on the lower portion of the screen to re-enter, in reverse order, the sequence presented by the application. Once the

candidate is finished, he/she clicks on the Continue button. If he/she makes a mistake, he/she clicks on the Reset button.

was correct. Although all this information is stored, no feedback is given to the candidate to avoid disrupting the flow of the test. Instead a brief summary is produced at the end of the last test.

The test proceeds in this fashion, generating a sequence of letters and asking the candidate to reverse it and re-enter it. The maximum sequence length, the number of trials per sequence length and the forward/reverse mode can all be altered by the test examiner beforehand using the administrator level in the application.

The functionality of this test is closest to how information is absorbed via reading, an extremely common learning tool and an almost universal practice in most cultures. As such, the visual memory test with letters can be viewed as representing one of the standard learning methods in the application.