2.3.2. Working Memory Assessment
Working memory was assessed by a battery set of memory tests consisting of word presentation, word recognition test, picture presentation, picture recognition test, simple reaction test, digit vigilance, choice reaction time, spatial, and numeric working memory, as previously mentioned [Word presentation test measured word recognition memory via recall capability. After a 15-word presentation (1 s/stimulus and 1 s for duration between stimuli), each subject had to recall the word that was previously presented as much as possible, and both response time and percentage of accuracy were recorded.Word recognition test was applied to measure the recognition memory via recognition capability. In this test, each subject was exposed to a 30-word set, which consisted of 15 new words and 15 old words that were previously presented in the word presentation test. During the presentation, subjects pressed “yes” button when the word was previously presented and pressed “no” button when the word was a new one. The reaction time and percentage of accuracy were recorded.Picture presentation test was performed in similar process as mentioned in the word presentation, except each subject was exposed to a set of 20 pictures, and each picture was presented for 3 s.Picture recognition test was also a recognition test, as mentioned in the picture recognition test, but the subjects were subjected to a 40-picture set consisting of 20 new pictures and 20 pictures that were previously presented in the picture presentation.Simple reaction time test measured the response time that each subject took to identify a stimulus on the monitor and press a response button.Digit vigilance test was carried out to determine sustained attention capability and psychomotor speed. This test was designed to measure vigilance during rapid visual tracking. Each subject had to identify and match the presentation of each digit in the central part of monitor with the digit that was provided in the right corner and press the provided button as quickly as possible when the presentation was matched with the targeted digit. The response time and accuracy of responses were recorded.Choice reaction time test was designed to measure alertness, or power of attention, and motor speed. Regarding this test, each subject was exposed to both targeted and non-targeted stimuli and had to press the provided button when the targeted stimuli were presented. Both response time and response accuracy were recorded.Spatial working memory test measured ability to recall spatial information. Each subject was exposed to a picture of a house containing nine windows. Four windows were illuminated, and subjects had to memorize the location of them as targeted stimuli. During the test, a series of house pictures with one illuminated window were provided to each subject, and the subjects had to match the location of the presented picture with the location of the targeted stimuli and press the provided button as quickly as possible when the matching was correct. The speed and accuracy of responses were also monitored.Numeric working memory test measured the ability to match 5 targeted numbers ranging from 0–9 that were presented on the screen before the test with a series of 30 numbers presented during the test. The subjects had to press the provided button as quickly as possible when the matching was correct, and both response time and accuracy of responses were recorded.