View larger image | Used to assess some cognitive impacts of food supplements, this test asks participants to hit a computer key when either of two combinations appears on-screen. Screens refresh once a second for five minutes, and target combinations may switch during the task. The example here prompts participants to respond when they see a letter and an even number (but only if green) or a number and vowel (but only if orange). L-theanine-rich tea boosted scores on this task, which measures one aspect of attention: the ability to plan and execute decisions. Credit: Source: E. De Bruin/Unilever