The interaction of study sequence presentation mode and response assignment reveals the effects of multiple computational systems on an immediate visual recognition task

Participants responded whether a single digit was in the immediately preceding digit sequence by pressing one of two keys as rapidly as possible while trying to avoid errors. Each participant performed four different kinds of sessions: Either all of the digits of the study sequence were presented in the same position or the digits were presented in successive positions from left to right. Either the same response was assigned to the right key and the different response to the left key or vice versa. Response time (RT) was an increasing function of the length of the study sequence. RT was an increasing function of the target's position in the study sequence when the different response was assigned to the right key. When the same response was assigned to the right key, RT was a decreasing function of the target's position in the study sequence when the study sequence had been presented in one location but there was no effect of target position on RT when the study sequence had been presented from left to right. The effects of study sequence length and target position were independent in the three conditions in which there was an effect of target position. Also, RT decreased for targets that had previously appeared as test items but RT increased for lures that had previously appeared as test items. The results confirm a dual-system hypothesis of recognition involving both the perceived recency of the target and the retrieval of the previous context of the target.