First comparative approach to touchscreen-based visual object-location paired-associates learning in humans and a non-human primate

A recent study suggests that the touchscreen-based dPAL task on visual object-location paired associates learning (PAL) allows effective translation from animal models to humans. Here, we adapted the task to a non-human primate (NHP), the grey mouse lemur, and provide first evidence for the successful comparative application of the task to humans and NHPs. Young human adults reach the learning criterion after considerably less sessions (one order of magnitude) than young, adult NHPs, which is likely due to faster and voluntary rejection of ineffective learning strategies in humans and almost immediate rule generalization. At criterion, however, all human subjects solved the task by either applying a visuo-spatial rule or, more rarely, by memorizing all possible stimulus combinations and responding correctly based on global visual information. An error-profile analysis in humans and NHPs suggests that successful learning in NHPs is comparably based either on the formation of visuo-spatial associative links or on more reflexive, visually-guided stimulus-response learning. The classification in the NHPs is further supported by an analysis of the individual response latencies, which are considerably higher in NHPs classified as spatial learners. Our results, therefore, support the high translational potential of the standardized, touchscreen-based dPAL task by providing first empirical and comparable evidence for two different cognitive processes underlying visual object-location paired-associates learning in primates.