In another republished developer diary from back when Shu Takumi was creating the Ace Attorney series, Capcom explain how the idea for Psyche Locks came into being. Psyche Locks made their debut in Ace Attorney: Justice for All, and here’s a portion of Takumi’s thought process while creating them:
The single most important concept behind the series’ gameplay is its simplicity — I strive to keep things simple so that even my mother can have fun while playing these games. That’s why finding and exposing lies is the sole gameplay mechanic that lies at the heart of every Ace Attorney game. If the games were any more complicated than that, I doubt my mother would be able to keep up. In fact, I’m sure of it. Sticking with this core concept, I thought it only appropriate to add a “find the lies” element to the investigation sections, too, after which, it became obvious as to what kind of gameplay mechanic would be needed.
You can read the full blog entry here. Capcom are re-publishing Takumi’s old developer diaries in celebration of Ace Attorney Trilogy for the Nintendo 3DS, which is slated for release this Fall.