What is the test for ineffective assistance of counsel?

falling below an objective standard of reasonableness under prevailing professional norms. Second, a defendant must establish that, absent counsel's error, it is reasonably probable that the verdict would have been more favorable to him. [Citations.]" (People v. Hawkins (1995) 10 Cal.4th 920, 940, abrogated on another ground in People v. Lasko (2000) 23 Cal.4th 101, 110.) "If the record does not shed light on why counsel acted or failed to act in the challenged manner, we must reject the claim on appeal unless counsel was asked for and failed to provide a satisfactory explanation, or there simply can be no satisfactory explanation. [Citations.]" (People v. Scott (1997) 15 Cal.4th 1188, 1212.)

Because the record sheds no light on why counsel did not request CALCRIM No. 1193, we cannot reach the merits of the claim of ineffective assistance of counsel. And on the record presented, there is no basis to conclude counsel's performance was deficient. As a tactical matter, competent counsel could rationally conclude that it would be counterproductive to request an instruction highlighting expert testimony supporting the victim's credibility. "A reasonable attorney may have tactically concluded that the risk of a limiting instruction ... outweighed the questionable benefits such instruction would provide." (People v. Maury (2003) 30 Cal.4th 342, 394.) Moreover, in light of our conclusion that any error was harmless, defendant cannot show he was prejudiced by counsel's purported error. (People v. Ledesma (1987) 43 Cal.3d 171, 217 [defendant must establish prejudice to obtain relief on an ineffective assistance claim].)