Jamie Lloyd's stark, riveting production of "The Effect" opens on Wednesday night. By the time its content "a human brain" is revealed, Lucy Prebble's heady and scintillating drama is already interrogating the biology of desire. What begins as the drug trial of an antidepressant shifts into more slippery territory when a flirtation develops between two participants. The drama that starts as the drug trial of an antidepressant shifts into more slippery territory when a flirtation develops between two participants. The drama that starts as the drug trial of an antidepressant shifts into more slippery territory when a flirtation develops between two participants.