EXPRESS: Serial memory for landmarks encountered during route navigation

The present study demonstrates similarities between route learning and classical tests of serial order memory. Here, we investigated serial memory for landmarks in a route learning task, in younger and older adults. We analysed data from a route learning task with 12 landmarks, reported by Hilton et al. (2021). Participants (88 younger and 77 older) learned a route using either a Fixed Learning (3 exposures to the route) or Flexible Learning (repeated exposures until successful navigation was achieved) procedure. Following route learning, participants completed Immediate Free Recall (IFR) and Free Reconstruction of Order (Free RoO) of the landmarks. We show clear acquisition of sequence memory for landmarks for both age groups, with Free RoO producing a bowed serial position curve. IFR produced recency effects but no primacy effects in fixed learning, with recency reduced following flexible learning for both age groups. Younger adults displayed a primacy bias for the first item recalled in both learning conditions, as did the older adults in the flexible learning condition. In contrast, older adults displayed a recency bias in the fixed learning condition. Evidence of contiguity in IFR was present only for younger adults in the flexible learning condition. Findings are broadly consistent with results from typical short-term list learning procedures and support the universality of sequence learning effects, which we demonstrate are generalisable to a navigation context.

The Role of Hand Movement in Spatial Serial Order Memory

Research on serial order memory has traditionally used tasks where participants passively view the items. A few studies that included hand movement showed that such movement interfered with serial order memory. In the present study of three experiments, we investigated whether and how hand movements improved spatial serial order memory. Experiment 1 showed that manual tracing (i.e., hand movements that traced the presentation of stimuli on the modified eCorsi block tapping task) improved the performance of backward recall as compared to no manual tracing (the control condition). Experiment 2 showed that the facilitation effect resulted from voluntary hand movements and could not be achieved via passive viewing of another person’s manual tracing. Experiment 3 showed that it was the temporal, not the spatial, signal within manual tracing that facilitated spatial serial memory.