Biomedical subjects

Amy L Shelton

Publications and source records attributed to Amy L Shelton.

9 recordsLinked to original sources

PubMed2006

Path information effects in visual and proprioceptive spatial learning.

Objects in an environment are often encountered sequentially during spatial learning, forming a path along which object locations are experienced. The present study investigated the effect of spatial information conveyed through the path in visual and proprioceptive learning of a room-sized spatial layout, exploring whether different modalities differentially depend on the integrity of the path. Learning object locations along a coherent path was compared with learning them in a spatially random manner. Path integrity had little effect on visual learning, whereas learning with the coherent path produced better memory performance than random order learning for proprioceptive learning. These results suggest that path information has differential effects in visual and proprioceptive spatial learning, perhaps due to a difference in the way one establishes a reference frame for representing relative locations of objects.

Adolescent↗

PubMed2006

Fixed versus dynamic orientations in environmental learning from ground-level and aerial perspectives.

Ground-level and aerial perspectives in virtual space provide simplified conditions for investigating differences between exploratory navigation and map reading in large-scale environmental learning. General similarities and differences in ground-level and aerial encoding have been identified, but little is known about the specific characteristics that differentiate them. One such characteristic is the need to process orientation; ground-level encoding (and navigation) typically requires dynamic orientations, whereas aerial encoding (and map reading) is typically conducted in a fixed orientation. The present study investigated how this factor affected spatial processing by comparing ground-level and aerial encoding to a hybrid condition: aerial-with-turns. Experiment 1 demonstrated that scene recognition was sensitive to both perspective (ground-level or aerial) and orientation (dynamic or fixed). Experiment 2 investigated brain activation during encoding, revealing regions that were preferentially activated perspective as in previous studies (Shelton and Gabrieli in J Neurosci 22:2711-2717, 2002), but also identifying regions that were preferentially activated as a function of the presence or absence of turns. Together, these results differentiated the behavioral and brain consequences attributable to changes in orientation from those attributable to other characteristics of ground-level and aerial perspectives, providing leverage on how orientation information is processed in everyday spatial learning.

Adult↗

PubMed2006

Individual skill differences and large-scale environmental learning.

Spatial skills are known to vary widely among normal individuals. This project was designed to address whether these individual differences are differentially related to large-scale environmental learning from route (ground-level) and survey (aerial) perspectives. Participants learned two virtual environments (route and survey) with limited exposure and tested on judgments about relative locations of objects. They also performed a series of spatial and nonspatial component skill tests. With limited learning, performance after route encoding was worse than performance after survey encoding. Furthermore, performance after route and survey encoding appeared to be preferentially linked to perspective and object-based transformations, respectively. Together, the results provide clues to how different skills might be engaged by different individuals for the same goal of learning a large-scale environment.

Altitude↗

PubMed2006

Environmental context influences visually perceived distance.

What properties determine visually perceived space? We discovered that the perceived relative distances of familiar objects in natural settings depended in unexpected ways onthe surrounding visual field. Observers bisected egocentric distances in a lobby, in a hallway, and on an open lawn. Three key findings were the following: (1) Perceived midpoints were too far from the observer, which is the opposite of the common foreshortening effect. (2) This antiforeshortening constant error depended on the environmental setting--greatest in the lobby and hall but nonsignificant on the lawn. (3) Context also affected distance discrimination; variability was greater in the hall than in the lobby or on the lawn. A second experiment replicated these findings, using a method of constant stimuli. Evidently, both the accuracy and the precision of perceived distance depend on subtle properties of the surrounding environment.

Adult↗

PubMed2005

Visual and proprioceptive representations in spatial memory.

It has been shown that spatial information can be acquired from both visual and nonvisual modalities. The present study explored how spatial information from vision and proprioception was represented in memory, investigating orientation dependence of spatial memories acquired through visual and proprioceptive spatial learning. Experiment 1 examined whether visual learning alone and proprioceptive learning alone yielded orientation-dependent spatial memory. Results showed that spatial memories from both types of learning were orientation dependent. Experiment 2 explored how different orientations of the same environment were represented when they were learned visually and proprioceptively. Results showed that both visually and proprioceptively learned orientations were represented in spatial memory, suggesting that participants established two different reference systems based on each type of learning experience and interpreted the environment in terms of these two reference systems. The results provide some initial clues to how different modalities make unique contributions to spatial representations.

Adolescent↗

PubMed2004

Orientation and perspective dependence in route and survey learning.

Three experiments investigated the role of egocentric orientation in subsequent memory for layouts learned via route (ground-level) and survey (aerial or overview) perspectives. Participants learned virtual environments from text descriptions (Experiment 1) or visual presentation (Experiments 1-3). In all experiments, scene recognition for route and survey images revealed a cost for switching perspective from study to test. In addition, recognition performance was facilitated when the test view matched the observer's learned orientation but only for the same-perspective recognition test. Experiment 3 demonstrated orientation dependence in judgments of relative direction, with a strong emphasis on initial heading. Together, these results suggest that establishing a reference system for representing spatial information is dependent on specific characteristics of the learning situation.

Cues↗

PubMed2004

Neural correlates of individual differences in spatial learning strategies.

Behavioral studies have shown that spatial skills, such as mental rotation, are correlated with preferences for certain types of spatial information. To be more specific, better mental rotation is associated with a preference for survey (maplike) spatial information relative to route (landmark or wayfinding) information. Functional MRI was used to investigate how individual differences in spatial skills (mental rotation) interact with encoding information from these 2 spatial perspectives. Despite similarities in performance across individuals for route and survey learning, differences between route and survey encoding activation increased with increased mental rotation ability in anterior cingulate, middle frontal gyrus, and postcentral gyrus. This correlation appeared to be due to decreasing activation during survey encoding and not activation changes during route learning. The results suggest that mental rotation skill contributes to survey or map learning but that alternative strategies can be used under the circumstances of this study to achieve equal performance.

Adult↗

PubMed2004

Spatial memory and perspective taking.

Giving directions or describing an environment often requires assuming perspectives other than one's own. We employed a spatial perspective-taking task to investigate how describing familiar versus novel perspectives affects subsequent memory. One participant (the director) viewed a display of objects from a single perspective and described the display to another participant (the matcher) from a perspective that varied by 0 degrees, 45 degrees, 90 degrees, 135 degrees, or 180 degrees from the viewing perspective. Following the description, we assessed the director's memory for the display, using judgments of relative direction, scene recognition, and map drawing. The participants imagined and recognized familiar views faster and/or more accurately than novel views. Moreover, different tasks showed different degrees of facilitation for the visually perceived and described views, suggesting multiple representations for different aspects of spatial memory. These findings emphasize the importance of understanding distinctions among spatial experiences and underscore differences in the tasks used to probe spatial memory.

Female↗

PubMed2002

Neural correlates of encoding space from route and survey perspectives.

The neural mechanisms underlying ground-level spatial navigation have been investigated, but little is known about other kinds of spatial navigation. Functional magnetic resonance imaging was used to identify differences in brain activation for two types of spatial information, information from the ground-level perspective (route) and information from a global perspective (survey). Participants were scanned during the encoding of two different virtual reality environments, one from each perspective. Comparisons of brain activation during route and survey encoding suggested that both types of information recruited a common network of brain areas, but with important differences. Survey encoding recruited a subset of areas recruited by route encoding, but with greater activation in some areas, including inferior temporal cortex and posterior superior parietal cortex. Route encoding, in contrast, recruited regions that were not activated by survey encoding, including medial temporal lobe structures, anterior superior parietal cortex, and postcentral gyrus. These differences in brain activation are associated with differences in memory performance for the two types of spatial information and contribute to specification of brain components of spatial knowledge.

Adult↗