The RVIP assessed the performance of visual attention mechanisms in remaining vigilant to periodically occurring events. The number of accurate responses to RVIP task was determined from the cognitive function computerised output. Participants monitored a series of single numbers (0-9) appearing in the centre of the screen. During the RVIP task, participants responded to consecutive sequences of three odd or three even numbers by pressing the corresponding response button as quickly and accurately as possible. This was identified in the output file by a value of '1' in 'TARGET=1' column. Also, the response time (in seconds) was recorded in the 'RT' column. If the subject correctly responded to the target, this was identified by a value of '1' in the 'CORRECT=1' column. The number of accurate responses was calculated as the total number of records where 'CORRECT=1' had a value of '1'. The test lasted approximately 9 minutes and number of accurate responses to stimulus was calculated.