Implicitly learning when to be ready: from instances to categories

[This article has been accepted for publication as a brief report for Psychonomic Bulletin & Review (https://www.springer.com/journal/13423) ]There is growing appreciation for the role of long-term memory in guiding temporalpreparation in speeded reaction time tasks. In experiments with variable foreperiodsbetween a warning stimulus (S1) and a target stimulus (S2), preparation is affected byforeperiod distributions experienced in the past, long after the distribution has changed.These effects from memory can shape preparation largely implicitly, outside of participants’awareness. Recent studies have demonstrated the associative nature of memory-guidedpreparation. When distinct S1s predict different foreperiods, they can trigger differentialpreparation accordingly. Here, we propose that memory-guided preparation allows foranother key feature of learning: the ability to generalize across acquired associations andapply them to novel situations. Participants completed a variable foreperiod task where S1was a unique image of either a face or a scene on each trial. Images of either category werepaired with different distributions with predominantly shorter versus predominantly longerforeperiods. Participants displayed differential preparation to never-before seen images ofeither category, without being aware of the predictive nature of these categories. Theycontinued doing so in a subsequent Transfer phase, after they had been informed that thesecontingencies no longer held. A novel rolling regression analysis revealed at a fine timescalehow category-guided preparation gradually developed throughout the task, and thatexplicit information about these contingencies only briefly disrupted memory-guidedpreparation. These results offer new insights into temporal preparation as the product of alargely implicit process governed by associative learning from past experiences.