Spatio-Temporal Structure, Path Characteristics, and Perceptual Grouping in Immediate Serial Spatial Recall

Abstract

Immediate serial spatial recall measures the ability to retain sequences of locations in short-term memory and is considered the spatial equivalent of digit span. It is tested by requiring participants to reproduce sequences of movements performed by an experimenter or displayed on a monitor. Different organizational factors dramatically affect serial spatial recall but they are often confounded or underspecified. Untangling them is crucial for the characterization of working-memory models and for establishing the contribution of structure and memory capacity to spatial span. We report five experiments assessing the relative role and independence of factors that have been reported in the literature. Experiment 1 disentangled the effects of spatial clustering and path-length by manipulating the distance of items displayed on a touchscreen monitor. Long-path sequences segregated by spatial clusters were compared with short-path sequences not segregated by clusters. Recall was more accurate for sequences segregated by clusters independently from path-length. Experiment 2 featured conditions where temporal pauses were introduced between or within cluster boundaries during the presentation of sequences with the same paths. Thus, the temporal structure of the sequences was either consistent or inconsistent with a hierarchical representation based on segmentation by spatial clusters but the effect of structure could not be confounded with effects of path-characteristics. Pauses at cluster boundaries yielded more accurate recall, as predicted by a hierarchical model. In Experiment 3, the systematic manipulation of sequence structure, path-length, and presence of path-crossings of sequences showed that structure explained most of the variance, followed by the presence/absence of path-crossings, and path-length. Experiments 4 and 5 replicated the results of the previous experiments in immersive virtual reality navigation tasks where the viewpoint of the observer changed dynamically during encoding and recall. This suggested that the effects of structure in spatial span are not dependent on perceptual grouping processes induced by the aerial view of the stimulus array typically afforded by spatial recall tasks. These results demonstrate the independence of coding strategies based on structure from effects of path characteristics and perceptual grouping in immediate serial spatial recall.

Pointing movements both impair and improve visuospatial working memory depending on serial position

“…Lastly, consistent with previous evidence (De Lillo, Kirby, & Poole, 2016;Kemps, 2001;Pieroni et al, 2011;Rossi-Arnaud et al, 2006;Rossi-Arnaudet et al, 2012), we found that order memory was significantly better for symmetrical arrays (both vertical and horizontal) than for random arrays, confirming that our participants took advantage of the structural properties of symmetrical patterns to enhance immediate spatial recall. Most importantly, we showed that pointing movements impaired memory for all types of arrays to the same extent, as indicated by the absence of significant interactions between stimulus type and encoding condition.…”

Differences in Encoding Strategy as a Potential Explanation for Age-Related Decline in Place Recognition Ability

“…In this way, a temporal structure of the place is created through eye movements (Rucci et al, 2018;Heuer and Rolfs, 2019), where a swap of object locations results in a swap along the temporal dimension. Usually such temporal encoding of space is evident when stimuli dynamically appear and disappear or are highlighted, in a sequence (De Lillo et al, 2016) and has its own independent contribution to memory from concurrently formed spatial representations (Heuer and Rolfs, 2019).…”

Sources of variation in search and foraging: A theoretical perspective

“…Additionally, they suggest that, for humans, the distance travelled is not the main factor that allows the reduction of memory load in this type of tasks. Rather, using a path that is compatible with the hierarchical coding of a patchy environment is more effective than using a shorter one (De Lillo et al, 2014;De Lillo et al, 2016). Detailed analyses of response times when patch size and number of parches is manipulated confirm the hierarchical nature of representations of these arrays in serial recall (De Lillo & Lesk, 2011).…”

“…The results of experiments where different sequence characteristics were manipulated, such as their path length and their conformity to a linear organisation (e.g. sequences with or without consecutive steps within the same row or column), show that linear organisation explains a larger portion of variance in recall than path length in humans (De Lillo et al, 2016).…”