Changing Verbal Label Assignments Selects the Memory System for Responses in an Immediate Visual Recognition Task

The dual system hypothesis posits the existence of two neural systems for memory and learning in the mammalian brain: the habit system and the improvisational system. This study sought to determine whether both systems are involved in a visual recognition task originally outlined in Sternberg (1966) and whether each system could be selectively engaged on the basis of response assignment. Seventeen undergraduate students participated in an immediate visual recognition task where they responded whether or not a test consonant was present in a previous study sequence of one to six consonants by pressing one key for same or another key for different. When the different response was assigned to the spatially right “J” key, reaction time for targets and lures was a function of the study sequence size, indicating that the study sequence was serially scanned and compared with the test item by the habit system. However, when the same response was assigned to the spatially right “J” key, reaction time was not a function of study sequence size, indicating that the test item was not compared with the study sequence and responses were instead determined by perceived recency/novelty of the test item by the improvisational system. Differences in reaction time depending on response assignment suggest the selection of one memory system over the other based on verbal labels assigned to response keys in different spatial locations. Verbal label refers to the label of same or different assigned to the response keys in the experiment instructions. Results expand upon Sternberg (1966)—which used the same visual recognition task design as this study but did not account for response assignment, obscuring evidence of contributions from both memory systems—and provide more evidence for the dual-system hypothesis by demonstrating the involvement of both memory systems in immediate visual recognition.