Constructing representations of spatial location from briefly presented displays.

Spatial memory and reasoning rely heavily on allocentric (often map-like) representations of spatial knowledge. While research has documented many ways in which spatial information can be represented in allocentric form, less is known about how such representations are constructed. For example: Are the very early, pre-attentive parts of the process hard-wired, or can they be altered by experience? We addressed this issue by presenting sub-saccadic (53 ms) masked stimuli consisting of a target among one to three reference features. We then shifted the location of the feature array, and asked participants to identify the target's new relative location. Experience altered feature processing even when the display duration was too short to allow attention re-allocation. The results demonstrate the importance of early perceptual processes in the creation of representations of spatial location, and the malleability of those processes based on experience and expectations.

Functional equivalence and spatial path memory.

Loomis, Klatzky, Avraamides, Lippa and Golledge ( 2007 ) suggest that, when it comes to spatial information, verbal description and perceptual experience are nearly functionally equivalent with respect to the cognitive representations they produce. We tested this idea for the case of spatial memory for complex paths. Paths consisted entirely of unit-length segments followed by 90-degree turns, thus assuring that a path could be described with equal precision using either an egocentric verbal description or a virtual self-motion experience. The verbal description was analogous to driving directions (e.g., turn left and go one block, then turn right, etc.) except in three dimensions (allowing rotation followed by up or down movement). Virtual self-motion was depicted as first-person travel through a 3D grid of featureless corridors. Comparison of these two conditions produced a result that may be surprising to some, but nevertheless appears to support the notion of functional equivalence: Virtual self-motion does not produce better path memory than verbal description, when care is taken to present equally precise path information. This result holds for even very complex paths and despite evidence from proximity-based interference that the memory representation of the path is spatial.

Representations and processes of human spatial competence.

This article presents an approach to understanding human spatial competence that focuses on the representations and processes of spatial cognition and how they are integrated with cognition more generally. The foundational theoretical argument for this research is that spatial information processing is central to cognition more generally, in the sense that it is brought to bear ubiquitously to improve the adaptivity and effectiveness of perception, cognitive processing, and motor action. We describe research spanning multiple levels of complexity to understand both the detailed mechanisms of spatial cognition, and how they are utilized in complex, naturalistic tasks. In the process, we discuss the critical role of cognitive architectures in developing a consistent account that spans this breadth, and we note some areas in which the current version of a popular architecture, ACT-R, may need to be augmented. Finally, we suggest a framework for understanding the representations and processes of spatial competence and their role in human cognition generally.

A computational model of spatial visualization capacity.

Visualizing spatial material is a cornerstone of human problem solving, but human visualization capacity is sharply limited. To investigate the sources of this limit, we developed a new task to measure visualization accuracy for verbally-described spatial paths (similar to street directions), and implemented a computational process model to perform it. In this model, developed within the Adaptive Control of Thought-Rational (ACT-R) architecture, visualization capacity is limited by three mechanisms. Two of these (associative interference and decay) are longstanding characteristics of ACT-R's declarative memory. A third (spatial interference) is a new mechanism motivated by spatial proximity effects in our data. We tested the model in two experiments, one with parameter-value fitting, and a replication without further fitting. Correspondence between model and data was close in both experiments, suggesting that the model may be useful for understanding why visualizing new, complex spatial material is so difficult.

Time Course of Location-Cuing Effects With a Probability Manipulation.

A location-cuing paradigm was used to study the effects of cue probability on the allocation of visual attention. A cue was used to indicate the likely location of a target (out of 4 possible target locations), with 8 cue-target onset intervals, ranging from 0 to 233 ms. There were 3 blocked proportions of correctly cued trials, 100%, 75%, and 50%. The observers had higher target discrimination accuracy at highly probable locations than at less probable locations, and these differences were maintained across all cue-target onset intervals. Thus, it appeared that the observers were allocating attention as a function of cue probability, with a consistent pattern throughout the time course of the development of attention. The consistent pattern across stimulus onset asynchronies (SOAs) suggests that the effects of time after cue and the effects of probability may rely on independent processes.

Attention Operating Characteristics in a Location-Cuing Task.

The authors studied the allocation of visual attention in the location-cuing paradigm in order to differentiate between 2 general classes of mechanisms: (a) switching attention across locations on different trials and (b) sharing attention across multiple locations within a trial. In Experiment 1, attention was directed by the use of central cues of 4 different cue validities: 100%, 80%, 50%, or 20% (in separate blocks). In Experiment 2, the percentage of correctly cued trials was fixed at 50%, but instructions and feedback were manipulated. The attention operating characteristic (AOC) curves provided evidence of sharing or hybrid (2-process) mechanisms. Thus, it appears that visual attention is characterized by a flexible allocation in response to task demands.