Biomedical subjects

Timothy P McNamara

Publications and source records attributed to Timothy P McNamara.

7 recordsLinked to original sources

PubMed2004

Allocentric and egocentric updating of spatial memories.

In 4 experiments, the authors investigated spatial updating in a familiar environment. Participants learned locations of objects in a room, walked to the center, and turned to appropriate facing directions before making judgments of relative direction (e.g., "Imagine you are standing at X and facing Y. Point to Z.") or egocentric pointing judgments (e.g., "You are facing Y. Point to Z."). Experiments manipulated the angular difference between the learning heading and the imagined heading and the angular difference between the actual heading and the imagined heading. Pointing performance was best when the imagined heading was parallel to the learning view, even when participants were facing in other directions, and when actual and imagined headings were the same. Room geometry did not affect these results. These findings indicated that spatial reference directions in memory were not updated during locomotion.

Female↗

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

Frames of reference in spatial memories acquired from language.

Four experiments examined reference systems in spatial memories acquired from language. Participants read narratives that located 4 objects in canonical (front, back, left, right) or noncanonical (left front, right front, left back, right back) positions around them. Participants' focus of attention was first set on each of the 4 objects, and then they were asked to report the name of the object at the location indicated by a direction word or an iconic arrow. The results indicated that spatial memories were represented in terms of intrinsic (object-to-object) reference systems, which were selected using egocentric cues (e.g., alignment with body axes). Results also indicated that linguistic direction cues were comprehended in terms of egocentric reference systems, whereas iconic arrows were not.

Cues↗

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↗

PubMed2003

Locomotion, incidental learning, and the selection of spatial reference systems.

In three experiments, we examined the effects of locomotion and incidental learning on the formation of spatial memories. Participants learned the locations of objects in a room and then made judgments of relative direction, using their memories (e.g., "Imagine you are standing at the clock, facing the jar. Point to the book"). The experiments manipulated the number of headings experienced, the amount of interaction with the objects, and whether the participants were informed that their memories of the layout would be tested. When participants were required to maintain a constant body orientation during learning (Experiment 1), they represented the layout in terms of a single reference direction parallel to that orientation. When they were allowed to move freely in the room (Experiment 2), they seemed to use two orthogonal reference axes aligned with the walls of the enclosing room. Extensive movement under incidental learning conditions (Experiment 3) yielded a mixture of these two encoding strategies across participants. There was no evidence that locomotion, interaction with objects, or incidental learning led to the formation of spatial memories that differed from those formed from static viewing.

Adult↗

PubMed2003

Egocentric and geocentric frames of reference in memory of large-scale space.

This experiment investigated the frames of reference used in memory to represent the spatial structure of a large-scale outdoor environment. Participants learned the locations of eight objects in an unfamiliar city park by walking through the park on one of two prescribed paths that encircled a large rectangular building. The aligned path was oriented with the building; the misaligned path was rotated by 45 degrees. Later, participants pointed to target objects from imagined vantage points using their memories. Pointing accuracy was higher in the aligned than in the misaligned path group, and the patterns of results differed: In the aligned condition, accuracy was higher for imagined headings parallel to legs of the path and for an imagined heading oriented toward a nearby lake, a salient landmark. In the misaligned condition, pointing accuracy was highest for the imagined heading oriented toward the lake, and decreased monotonically with angular distance. These results indicated that locations of objects were mentally represented in terms of frames of reference defined by the environment but selected on the basis of egocentric experience.

Female↗

PubMed2002

Intrinsic frames of reference in spatial memory.

Three experiments investigated the frames of reference used in memory to represent the spatial structure of the environment. Participants learned the locations of objects in a room according to an intrinsic axis of the configuration; the axis was different from or the same as their viewing perspective. Judgments of relative direction using memory were most accurate for imagined headings parallel to the intrinsic axis, even when it differed from the viewing perspective, and there was no cost to learning the layout according to a nonegocentric axis. When the shape of the layout was bilaterally symmetric relative to the intrinsic axis of learning, novel headings orthogonal to that axis were retrieved more accurately than were other novel headings. These results indicate that spatial memories are defined with respect to intrinsic frames of reference, which are selected on the basis of egocentric experience and environmental cues.

Adult↗