Selective scanpath repetition during memory-guided visual search


INTRODUCTION: Visual stimulus repetition has been shown to improve processing efficiency and performance on recognition memory tasks. According to scanpath theory, memory-based repetition effects are mediated by repetition of the pattern of fixations or “scanpath” elicited during stimulus encoding at subsequent retrieval. However, it remains unclear how scanpath repetition supports efficiency gains on goal-directed tasks.$backslash$n$backslash$nMETHODS: The present study used eye-movement monitoring to test the predictions of scanpath theory against a memory-based visual search task. Younger and older subjects were instructed to find a changing target within a flickering naturalistic scene. Eye-movement search efficiency measures were compared across novel (V1) and repeated (V2) image viewings. A modified string-edit similarity measure was used to compare V1 and V2 scanpaths.$backslash$n$backslash$nRESULTS: Younger adults searched more efficiently than older adults, indexed by both search time and number of fixations. An increase in search efficiency was observed for repeated images relative to novel images. This effect did not differ by age. Time-binned scanpath similarity analysis revealed repetition of initial and final V1 fixations at V2, with older adults repeating more initial V1 fixations than young adults. Consistent with previous findings, early scanpath similarity correlated negatively with search time at test. However, similarity of V2 fixations to middle V1 fixations predicted poor search performance in young adults.$backslash$n$backslash$nCONCLUSION: We conclude that scanpath compression mediates increased search efficiency by selectively recapitulating encoding fixations that provide goal-relevant input. Subtle age differences in early scanpath repetition were additionally detected using these measures. Results support and extend theories of eye-movement-based repetition effects to account for efficiency gains on visual search as a function of goal-relevance and memory. Meeting abstract presented at VSS 2015.

Visual Cognition