Does pointing facilitate the recall of serial positions in visuospatial working memory?

Charting the Diversity of Strategic Processes in Visuospatial Short-Term Memory

Despite the abundant literature on visuospatial short-term memory, researchers have devoted little attention to strategic processes: What procedures do subjects implement to memorize visuospatial material? Evidence for various strategies exists, but it is spread across a variety of fields. This integrative review of the literature brings together scattered evidence to provide an overview of strategic processes in visuospatial memory tasks. The diversity of strategies and their proposed operating mechanisms are reviewed and discussed. The evidence leads to proposing seven broad strategic processes used in visuospatial short-term memory, each with multiple variants. Strategies can vary across individuals, but the same subjects also appear to use multiple strategies depending on the perceptual features of to-be-remembered displays. These results point to a view of visuospatial strategies as a functional library of facilitatory processes on which subjects can draw to support visuospatial short-term memory performance. Implications are discussed for the difference between visual and spatial tasks, for the appropriate measurement of strategic behaviors, and for the interpretation of performance in visuospatial memory tasks.

On-item fixations during serial encoding do not affect spatial working memory

Ample evidence suggests that there is overlap between the eye-movement system and spatial working memory. Such overlapping structures or capacities may result in interference on the one hand and beneficial support on the other. We investigated eye-movement control during encoding of verbal or spatial information, keeping the display the same between tasks. Saccades to to-be-encoded items were scarce during spatial encoding in comparison with verbal encoding. However, despite replicating this difference across different tasks (serial, free recall) and presentation modalities (simultaneous, sequential presentation), we found no relation between item fixations and memory performance-that is, no costs or benefits. Inducing a change from covert to overt encoding did not affect spatial memory performance as well. In contrast, regressive fixations on prior items, that were no longer on the screen, were associated with increased spatial memory performance. Regressions occurred mainly at the end of the encoding period and were targeted at the first presented item. Our results suggest a dissociation between two types of fixations that accompany serial spatial memory: On-item fixations are epiphenomenal; regressions indicate rehearsal or output preparation.

Pointing movements and visuo-spatial working memory in a joint setting: the role of motor inhibition

Previous studies have shown that, under specific conditions, arrays that have been pointed at encoding are recognized better than passively viewed ones. According to one interpretation, the superior recognition of pointed-to arrays can be explained by the motor inhibition of passively viewed arrays. The present study sought to determine whether a similar motor inhibition can be induced also when the participants observed a co-actor perform the pointing movements. Participants were presented with two spatial arrays, one of which was encoded via observation only (the no-move array), while the other was encoded with pointing movements (the move array); movements were performed either by the participant or by the experimenter. Experiment 1 replicated the advantage of self-pointed arrays over passively viewed arrays. Experiment 2 showed that, when participants passively observed the pointing movements performed by the experimenter, move arrays were recognized no better than no-move arrays. Finally, Experiment 3 demonstrated that, in a joint-action condition in which participants alternated with the experimenter in making pointing movements, the advantage of experimenter-pointed arrays over passively viewed arrays was significant and similar in size to the advantage produced by self-performed movements. Importantly, a series of cross-experiment comparisons indicated that the higher recognition of both self- and experimenter-pointed arrays in Experiment 3 could be explained by the motor inhibition of no-move arrays. We propose that, in a joint condition, the pointing movements performed by the experimenter were represented in the same functional way as self-performed movements and that this produced the motor inhibition of passively viewed arrays.

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

Two experiments investigated the effects of pointing movements on the item and order recall of random, horizontal, and vertical arrays consisting of 6 and 7 squares (Experiment 1) or 8 and 9 squares (Experiment 2). In the encoding phase, participants either viewed the items passively (passive-view condition) or pointed towards them (pointing condition). Then, after a brief interval, they were requested to recall the locations of the studied squares in the correct order of presentation. The critical result was that, for all types of arrays, the effects of the encoding condition varied as a function of serial position: for the initial and central positions accuracy was higher in the passive-view than in the pointing condition (confirming the standard inhibitory effect of pointing movements on visuospatial working memory), whereas the reverse pattern occurred in the final positions-showing a significant advantage of the pointing condition over the passive-view condition. Findings are interpreted as showing that pointing can have two simultaneous effects on the recall of spatial locations, a positive one due to the addition of a motor code and a negative one due to the attentional requirements of hand movements, with the net impact on serial recall depending on the amount of attention resources needed for the encoding of each position. Implications for the item-order hypothesis and the perceptual-gestural account of working memory are also discussed.