The inhibitory control task (ICT) is a computerized psychometric test that has been introduced recently as a diagnostic tool for MHE. It measures the ability to sustain attention and to inhibit responses to relevant stimuli, 2 basic cognitive domains that are impaired in MHE. During the ICT, the patient is presented with a continuous stream of letters at 500-ms intervals and interspersed within these letters are the letters X and Y. Subjects are instructed to only respond when the letters "X" and "Y" are alternated (called targets), independent of the letters between them. In contrast, patients are instructed to refrain from responding, i.e. inhibit their response, when "X" and "Y" are not alternating (called lures). Higher rates of target response, lower rates of lure response and shorter reaction times indicate better attention and response inhibition. One study by Bajaj et al. (2008) showed the ICT to be a reliable test with 87% sensitivity for the diagnosis of MHE, with MHE patients having higher ICT lures and lower targets compared to patients without MHE.