Explicit and implicit memory for the QWERTY keyboard: the role of motor simulation and deictic gestures.

In three experiments, we investigated explicit and implicit knowledge about the location of letters on the QWERTY keyboard in young students, and the mechanisms involved. Participants completed a verbal report task in which they were asked to locate the 21 letters of the Italian alphabet on a blank QWERTY keyboard (explicit memory). Subsequently, they carried out a motor production task, i.e., typing letters on a blank keyboard (implicit memory). Consistent with previous studies and several theories emphasizing the importance of implicit knowledge in typing, results showed that explicit knowledge about the QWERTY keyboard is systematically worse than procedural knowledge (Experiment 1). These two types of knowledge, however, are related. Second, we showed that explicit memory for letter position was affected when participants were engaged in a secondary task that required hands/arms movements. Specifically, loading participants' sensorimotor resources led to a decrease in explicit memory performance when the secondary task required hand/arm movements (hand/arms tapping) compared to when it required legs-feet movements (control condition). This result suggests that explicit knowledge is modulated by sensorimotor simulation (Experiment 2). Third, compared to a purely verbal response, pointing to the key on the keyboard did not improve explicit memory accuracy (Experiment 3). Taken together, the results indicate that sensorimotor simulation, and not just gestures, modulates the accessibility to explicit mental representations of verbal/spatial material, like letters on a keyboard.