Neuropsychological assessment

6.2.2.1.1Card Sort

The Card Sort test was based on the Wisconsin Card Sorting Test (Berg, 1948) and part of the Colorado Assessment Tests (CATS) test battery. The Card Sort test measured set-shifting, cognitive flexibility and problem-solving abilities (Baune, Czira, Smith, Mitchell, & Sinnamon, 2012). Four stimulus cards, similar to playing cards, appeared at the top of the screen, distinguished by colour, type of shape and number of shapes. For example, Card 1 had one red diamond; Card 2 had two green spades, Card 3 had three yellow clubs and Card 4 had four blue hearts. Below the four stimulus cards there was a single card called the key card, which participants had to match to one of the stimulus cards. Participants were informed whether their match was correct. A correct match was determined by the matching pattern: colour, shape or number. After 10 correct selections, the pattern changed, for example, from colour to shape. A total of six categories (two each of colour, shape and number) were needed to complete the task, or

the task would stop after 120 matching attempts. Participants were not warned of the pattern change and had to discover the new pattern themselves, using the feedback provided.

The items being measured were perseverative errors, non-perseverative errors and sorting categories completed (a total of six). Perseverative errors occurred when the matching pattern changed but the participant continued to use the previous matching pattern. For example, if the matching pattern changed from colour to shape, but the participant continued to match using colour, then a perseverative error occurred. Non- perseverative errors included both ‘failure to maintain set’ and ‘efficient errors’. Failure to maintain set refers to errors made through lack of concentration or interference; for example, a participant is matching correctly using colour and then makes an error by not matching by colour when the pattern has not changed. Efficient errors occurred when errors were made when the matching pattern changed and the participant tried to discover the new pattern (shifting set). The successful completion of a card-sorting test requires the ability to think abstractly, selectively attend to a particular perceptual dimension, and shift cognitive set (Merriam et al., 1999).

6.2.2.1.2Tower of London (ToL)

The computerised CATS version of the ToL is a variation of the Tower of Hanoi (Shallice, 1982). The ToL tests spatial problem solving, spatial memory, and planning ability (Carder, Handley, & Perfect, 2004) and is used to study frontal lobe dysfunctions (Berg & Byrd, 2002). Coloured balls are placed on three, four or five vertical pegs. Participants are required to rearrange the balls from their original position into a different specific configuration, which is shown on the screen, with each vertical peg able to hold only a limited number of coloured balls. The number of times a coloured ball is moved to achieve the new configuration that is greater than the optimum amount

is measured; in essence, excess moves. In total, the participant undergoes 21 trials, seven for each of three, four or five pegs.

6.2.2.1.3N-back

The computerised CATS version of N-back was used to test updating. It consisted of three levels: 1-back, 2-back and 3-back. N-back requires monitoring, updating and manipulating remembered information (Owen et al., 2005). In this version, seven uppercase letters (A, E, I, J, N, O and T) were used, with one letter flashed on the screen every four seconds in a randomised order. In the 1-back trial, the participants had to determine whether the current letter was the same as the letter that had appeared ‘one back’ or previously and then press the corresponding ‘yes’ or ‘no’ key. Following the same idea for the 2-back and 3-back trials, the participants had to determine whether the current letter was the same as the letter two letters back and three back, respectively. The percentages of correct answers for 1-back, 2-back and 3-back were recorded. 6.2.2.1.4Stroop Test

The Victoria Stroop Test (VST) (Troyer, Leach, & Strauss, 2006) was used to measure response inhibition. The VST is a brief, easily administered, psychometrically sound version of the Stroop Test (Troyer et al., 2006). The VST consisted of three levels, each containing a 5x10 matrix of coloured dots (Level 1), non-coloured words, words coloured as per the coloured dots in Level 1 (Level 2), or words coloured in an incongruous font colour (Level 3). The participant was required to name the colour of the dots or text as quickly as possible, reading from left to right. The time to complete each level can be calculated singularly but in addition, a Stroop total time is calculated using the Golden Method (Golden, 1978), in which Stroop total = Stroop Level 3 - (Stroop Level 1 + Stroop Level 2).

6.2.2.1.5Verbal Recall

Verbal learning and memory was assessed using the CATs test of Verbal Recall, which is based on the Rey Auditory Verbal Learning Test (Rey, 1964). In the task, the instructor read a list of 15 words as they were flashed on a computer screen. The screen was visible to the instructor but not to the participant. The participants were then required to recall the 15 words verbally. There was no delay. After a 20-second pause, the process was repeated with the same words read out, but in a different order, for a total of five trials. The number of correctly recalled words for each trial and the total number of words recalled were recorded.

6.2.2.1.6Social Cognition Tests

Social perception was assessed using three tasks: affect naming, prosody face matching and prosody pair matching, which were sourced from the Advanced Clinical Solutions for WAIS-IV and WMS-IV Social Cognition Stimulus Book. In affect naming,

a series of photos of faces were examined by the participant and the expression on the face was matched to a list of feelings. In the prosody face-matching task, a photo of a face was selected to match the emotional content of a verbal statement that was played on the computer. In prosody pair matching, the emotional content of a verbal statement was first matched with a selection of photos of interacting pairs and then the meaning of the statement was determined.