What is the basis for a finding that a defendant is incompetent to stand trial?

Appellant relies on People v. Lightsey (2012) 54 Cal.4th 668, but, unlike the instant case, the evidence in Lightsey of the defendant's incompetence was substantial. His current and former defense counsel asked the court to declare a doubt regarding his mental competence, and several of his lawyers submitted declarations expressing doubts about his mental stability and his ability to understand the nature of the proceedings. (See id. at pp. 685-686, 688, 689-690.) In addition, one of two medical experts concluded he was not competent to stand trial. When defense counsel again requested that the court suspend proceedings in order to evaluate the defendant's mental competence, the court expressed the belief that the defendant voluntarily chose not to cooperate with counsel and "merely had a bad 'attitude.'" (Id. at p. 690.)