The influence of position effects of repeated items in non-strict sequences on the distance effect and reverse distance effect

Abstract

This study systematically investigated the sequential processing mechanisms in non-strict sequences (sequences containing repeated items) through four experiments, examining how sequence length, item repetition position, and material type modulate distance effect patterns. Experiments 1–2 revealed that both non-strict numerical and alphabetical triplets exhibited stable canonical distance effects (CDE), which were not modulated by repetition position. Experiments 3–4 demonstrated that non-strict quadruplets generally showed reverse distance effects (RDE); however, in numerical materials, RDE disappeared when repeated items occupied middle positions, whereas in alphabetical materials, RDE remained stable regardless of repetition position. The study proposed three core theoretical frameworks: The Endpoint Position Effect explains why repetition position does not affect distance effects in triplets—when endpoint information is sufficient to determine sequence direction, participants directly engage magnitude comparison mechanisms. The Anchor Interference Hypothesis reveals the mechanism by which middle repetition eliminates RDE in quadruplets—middle repetition disrupts the integrity of processing anchors, forcing a strategy shift from memory retrieval to item-by-item comparison. The Representation-Processing Integration Model (RPIM) integrates these perspectives, proposing that the dynamic interplay between representational strength and processing strategy determines distance effect patterns. Numerical representations, being more compact, are more sensitive to structural disruption, while alphabetical representations, being more distributed, rely more heavily on spatial scanning. This framework provides a unified theoretical foundation for understanding sequential processing in non-strict sequences.