Acquisition vs. Memorization Trade-Offs Are Modulated by Walking Distance and Pattern Complexity in a Large-Scale Copying Paradigm

In a “block-copying paradigm”, subjects were required to copy a configuration of colored blocks from a model area to a distant work area, using additional blocks provided at an equally distant resource area. Experimental conditions varied between the inter-area separation (walking distance) and the complexity of the block patterns to be copied. Two major behavioral strategies were identified: in the memory-intensive strategy, subjects memorize large parts of the pattern and rebuild them without intermediate visits at the model area. In the acquisition-intensive strategy, subjects memorize one block at a time and return to the model after having placed this block. Results show that the frequency of the memory-intensive strategy is increased for larger inter-area separations (larger walking distances) and for simpler block patterns. This strategy-shift can be interpreted as the result of an optimization process or trade-off, minimizing combined, condition-dependent costs of the two strategies. Combined costs correlate with overall response time. We present evidence that for the memory-intensive strategy, costs correlate with model visit duration, while for the acquisition-intensive strategy, costs correlate with inter-area transition (i.e., walking) times

Learning the Optimal Control of Coordinated Eye and Head Movements

Various optimality principles have been proposed to explain the characteristics of coordinated eye and head movements during visual orienting behavior. At the same time, researchers have suggested several neural models to underly the generation of saccades, but these do not include online learning as a mechanism of optimization. Here, we suggest an open-loop neural controller with a local adaptation mechanism that minimizes a proposed cost function. Simulations show that the characteristics of coordinated eye and head movements generated by this model match the experimental data in many aspects, including the relationship between amplitude, duration and peak velocity in head-restrained and the relative contribution of eye and head to the total gaze shift in head-free conditions. Our model is a first step towards bringing together an optimality principle and an incremental local learning mechanism into a unified control scheme for coordinated eye and head movements

Stability of (C)overt Attention Strategies in a Digital CORSI Task: An Eye-Tracking Study

The Corsi block-tapping task (CBTT) is a classic and well-established spatial working memory task in humans whichdemands internal computations (memorizing of Corsisequences, organizing and updating the memorandum,and recall processes) as well as (c)overt shifts of attentionto facilitate externalized rehearsal serving to maintain theCorsi sequences during the retention phase. To under-stand the relevance of (c)overt attention in CORSI tasks,28 participants had to solve different CBTT conditions(within-subject design), while eye position and pupil sizewere monitored. As CBTT, we introduced a novel anddigital version in which (a) the difficulty of the memoran-dum (sequence lengths reaching from 3 to 10) was con-trolled, (b) the execution of (c)overt attention during theretention phase was manipulated, and (c) (c)overt shifts ofattention were quantified. We present behavioral datashowing and characterizing for the first time the interindi-vidual variability but intraindividual stability as well as therange in deploying (c)overt attention strategies in CBTT

View-based organization and interplay of spatial working and long-term memories.

Space perception provides egocentric, oriented views of the environment from which working and long-term memories are constructed. "Allocentric" (i.e. position-independent) long-term memories may be organized as graphs of recognized places or views but the interaction of such cognitive graphs with egocentric working memories is unclear. Here we present a simple coherent model of view-based working and long-term memories, together with supporting evidence from behavioral experiments. The model predicts (i) that within a given place, memories for some views may be more salient than others, (ii) that imagery of a target square should depend on the location where the recall takes place, and (iii) that recall favors views of the target square that would be obtained when approaching it from the current recall location. In two separate experiments in an outdoor urban environment, pedestrians were approached at various interview locations and asked to draw sketch maps of one of two well-known squares. Orientations of the sketch map productions depended significantly on distance and direction of the interview location from the target square, i.e. different views were recalled at different locations. Further analysis showed that location-dependent recall is related to the respective approach direction when imagining a walk from the interview location to the target square. The results are consistent with a view-based model of spatial long-term and working memories and their interplay

Downtown map of Tübingen with target square “Marktplatz”, near interview locations (A–H) and location-dependent vectors drawn at these locations.

<p>Vectors at six (blue circles) out of eight interview sites point towards the target square ( or better). For two locations (C, D; red), no significant orientation effect could be found. Vector length reaches from zero to one (radius of circle) and is a measure of concentration of the location-dependent vectors. Map source: © OpenStreetMap contributors.</p

Location-dependent vectors from Fig. 8, rotated to align the air-line directions from all interview locations to degrees (letters indicate interview location).

<p>Vectors are significantly biased towards the theoretical direction (green line, ). Vector length reaches from zero to one (radius of circle) and is a measure of concentration of the location-dependent vectors.</p

Sketch orientation frequencies for drawing the “Holzmarkt”.

<p>a) Orientation frequencies of the near interview locations (A–J). The obtained frequencies differed significantly from each other. b) Orientation frequencies of the distant interview locations (North to West). c, d) Average orientation frequencies with standard deviation of the near and distant condition, respectively. The -axis shows the frequency of sketch map orientations, the -axis the rated orientation (North, East, South, West).</p

Examples of sketches of the “Holzmarkt” from four participants.

<p>The blue arrows indicate the orientation the sketch was rated in. Note the inscriptions “Stiftskirche” or “Kirche” referring to the landmark church building located at this square (see also view A3 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0112793#pone-0112793-g001" target="_blank">Figure 1a</a>). The parallel lines mark a flight of stairs leading from the square to the church, the circles mark a fountain at the Western side of the square.</p