No evidence for chunking in spatial memory of route experience.

Spatial memory is important for supporting the successful completion of everyday activities and is a particularly vulnerable domain in late life. Grouping items together in memory, or chunking, can improve spatial memory performance. In memory for desktop scale spaces and well-learned large-scale environments, error patterns suggest that information is chunked in memory. However, the chunking mechanisms involved in learning new large-scale, navigable environments are poorly understood. In five experiments, two of which included young and older adult samples, participants watched movies depicting routes through building-sized environments while attempting to remember the locations of cued objects. We tested memory for the cued objects with virtual pointing, distance estimation, and map drawing tasks after participants viewed each route. Patterns of error failed to show consistent evidence of chunking in spatial memory across all experiments. One possibility is that chunking in spatial memory relies on visual perceptual grouping mechanisms that are not in play during encoding of large-scale spaces encountered through extended route experiences that do not afford concurrent viewing of target locations. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Virtual navigation in healthy aging: Activation during learning and deactivation during retrieval predicts successful memory for spatial locations.

Spatial navigation and spatial memory are two important skills for independent living, and are known to be compromised with age. Here, we investigate the neural correlates of successful spatial memory in healthy older adults in order to learn more about the neural underpinnings of maintenance of navigation skill into old age. Healthy older adults watched a video shot by a person navigating a route and were asked to remember objects along the route and then attempted to remember object locations by virtually pointing to the location of hidden objects from several locations along the route. Brain activity during watching and pointing was recorded with functional MRI. Larger activations in temporal and frontal regions during watching, and larger deactivations in superior parietal cortex and intraparietal sulcus during pointing, were associated with smaller location errors. These findings suggest that larger evoked responses during learning of spatial information coupled with larger deactivation of canonical spatial memory regions at retrieval are important for effective spatial memory in late life.

Event memory uniquely predicts memory for large-scale space.

When a person explores a new environment, they begin to construct a spatial representation of it. Doing so is important for navigating and remaining oriented. How does one's ability to learn a new environment relate to one's ability to remember experiences in that environment? Here, 208 adults experienced a first-person videotaped route, and then completed a spatial map construction task. They also took tests of general cognitive abilities (working memory, laboratory episodic memory, processing speed, general knowledge) and of memory for familiar, everyday activities (event memory). Regression analyses revealed that event memory (memory for everyday events and their temporal structure), laboratory episodic memory (memory for words and pictures) and gender were unique predictors of spatial memory. These results implicate the processing of temporal structure and organization as an important cognitive ability in large-scale spatial-memory-from-route experience. Accounting for the temporal structure of people's experience while learning the layout of novel spaces may improve interventions for addressing navigation problems.

Age differences in spatial memory for mediated environments.

Compared with younger adults, older adults have more difficulty with navigation and spatial memory in both familiar and unfamiliar domains. However, the cognitive mechanisms underlying these effects have been little explored. We examined three potential factors: (a) use of and coordination across spatial reference frames, (b) nonspatial cognitive abilities, and (c) the ability to segment a route into effective chunks. In two experiments, healthy young and older adults watched videos of navigation in a novel environment and had to remember the placement of landmarks along the route. Participants completed three spatial memory tasks-a virtual pointing task, a distance estimation task, and sketch map drawing-for each route. The pointing task depends on updating and accessing the updated egocentric reference frame relative to other frames. Map drawing may rely more on environment-centered processing. The distance estimation task could be solved using either frame of reference. Last, participants segmented each route. In a separate session, working memory, processing speed, and verbal memory were assessed. Older adults performed less well on all spatial tasks compared with younger adults; aging had a stronger negative effect on pointing performance. This may point to impairments in older adults' ability to update and coordinate information across reference frames. Performance on all spatial tasks was predicted by nonspatial task performance. Segmentation did not predict spatial memory. These results underline the importance of situating age differences in navigation in the context of basic transformations of spatial reference frames, and also in the context of nonspatial cognitive abilities. (PsycINFO Database Record

Attentional focus affects how events are segmented and updated in narrative reading.

Readers generate situation models representing described events, but the nature of these representations may differ depending on the reading goals. We assessed whether instructions to pay attention to different situational dimensions affect how individuals structure their situation models (Exp. 1) and how they update these models when situations change (Exp. 2). In Experiment 1, participants read and segmented narrative texts into events. Some readers were oriented to pay specific attention to characters or space. Sentences containing character or spatial-location changes were perceived as event boundaries-particularly if the reader was oriented to characters or space, respectively. In Experiment 2, participants read narratives and responded to recognition probes throughout the texts. Readers who were oriented to the spatial dimension were more likely to update their situation models at spatial changes; all readers tracked the character dimension. The results from both experiments indicated that attention to individual situational dimensions influences how readers segment and update their situation models. More broadly, the results provide evidence for a global situation model updating mechanism that serves to set up new models at important narrative changes.

Posttraumatic Stress and the Comprehension of Everyday Activity.

People with Posttraumatic Stress Disorder (PTSD) often report difficulties with attention and memory on tasks that are unrelated to their trauma. One important component of everyday event comprehension is the segmentation of ongoing activity into meaningful events. The present study asked whether PTSD symptom severity was associated with impaired segmentation and memory for neutral, ongoing activity. A sample of 137 participants, ages 21-79, completed event segmentation and memory tasks, general cognitive functioning tasks, and questionnaires assessing PTSD symptom severity. People with higher levels of PTSD symptoms had poorer event segmentation and event memory performance. Hierarchical multiple regression analyses demonstrated that PTSD symptom severity explained unique variance in event segmentation performance, even after controlling for general cognitive function. These results suggest that interventions aimed at improving event comprehension may help compensate for memory disruptions in PTSD.

APOE ε4 genotype predicts memory for everyday activities.

The apolipoprotein E (ApOE) ε4 allele is associated with neuropathological buildup of amyloid in the brain, and with lower performance on some laboratory measures of memory in some populations. In two studies, we tested whether ApOE genotype affects memory for everyday activities. In Study 1, participants aged 20-79 years old (n = 188) watched movies of actors engaged in daily activities and completed memory tests for the activities in the movies. In Study 2, cognitively healthy and demented older adults (n = 97) watched and remembered similar movies, and also underwent structural MRI scanning. All participants provided saliva samples for genetic analysis. In both samples we found that, in older adults, ApOE ε4 carriers demonstrated worse everyday memory performance than did ε4 noncarriers. In Study 2, ApOE ε4 carriers had smaller medial temporal lobes (MTL) volumes, and MTL volume mediated the relationship between ApOE genotype and everyday memory performance. These everyday memory tasks measure genetically determined cognitive decline that can occur prior to a clinical diagnosis of dementia. Further, these tasks are easily administered and may be a useful clinical tool in identifying ε4 carriers who may be at risk for MTL atrophy and further cognitive decline that is a common characteristic of the earliest stages of Alzheimer's disease.

Getting completely turned around: how disorientation impacts subjective straight ahead.

In manipulating a pointer to indicate subjective straight ahead (SSA), participants were more variable after a series of whole-body rotations in conjunction with external sensory blockade than after external sensory blockade alone. The variability of reported SSA did not increase consequent to a temporal delay matched to the time taken by the rotation procedure. These results suggest that an observer's egocentric reference frame is more complex and less stable than has previously been thought.

Analyzing distances in a frontal plane.

In an exploration of the process whereby horizontal and vertical components are extracted from distances between pairs of points, participants made speeded absolute distance judgments­deciding whether horizontal distances between pairs of points in a frontal plane exceeded a criterion distance. Judgments reflected the horizontal and vertical distances between the points. Three accounts of the results were considered. (1) Only the overall distance between two points was directly available to judgment processes; the horizontal or vertical distance between the points was available only to the extent that the horizontal and vertical positions of the points were differentially weighted prior to the assessment of overall distance. (2) The perceptual effects of positions on the horizontal and vertical dimensions were collapsed onto a composite dimension. (3) The decision criterion for the distance judgment considered both the horizontal and vertical distances between the points. In support of the overall distance account, (1) performance in the distance judgment task was facilitated by repetition of the same overall distance from trial to trial, but not by repetition of the distance on the composite dimension or by repetition of horizontal or vertical distance; (2) differential weighting that the overall distance account predicted for the absolute distance judgments was reflected in concurrent relative distance judgments pitting horizontal against vertical distance, counter to the composite dimension account, which sees the horizontal and vertical dimensions as collapsing onto the composite dimension in balanced, symmetrical fashion, and counter the decisional account, given that no criterion is required for the relative judgment.

Event segmentation ability uniquely predicts event memory.

Memory for everyday events plays a central role in tasks of daily living, autobiographical memory, and planning. Event memory depends in part on segmenting ongoing activity into meaningful units. This study examined the relationship between event segmentation and memory in a lifespan sample to answer the following question: Is the ability to segment activity into meaningful events a unique predictor of subsequent memory, or is the relationship between event perception and memory accounted for by general cognitive abilities? Two hundred and eight adults ranging from 20 to 79years old segmented movies of everyday events and attempted to remember the events afterwards. They also completed psychometric ability tests and tests measuring script knowledge for everyday events. Event segmentation and script knowledge both explained unique variance in event memory above and beyond the psychometric measures, and did so as strongly in older as in younger adults. These results suggest that event segmentation is a basic cognitive mechanism, important for memory across the lifespan.

Two-category place representations persist over body rotations.

We explored a system that constructs environment-centered frames of reference and coordinates memory for the azimuth of an object in an enclosed space. For one group, we provided two environmental cues (doors): one in the front, and one in the rear. For a second group, we provided two object cues: a front and a rear cue. For a third group, we provided no external cues; we assumed that for this group, their reference frames would be determined by the orthogonal geometry of the floor-and-wall junction that divides a space in half or into multiple territories along the horizontal continuum. Using Huttenlocher, Hedges, and Duncan's (Psychological Review 98: 352-376, 1991) category-adjustment model (cue-based fuzzy boundary version) to fit the data, we observed different reference frames than have been seen in prior studies involving two-dimensional domains. The geometry of the environment affected all three conditions and biased the remembered object locations within a two-category (left vs. right) environmental frame. The influence of the environmental geometry remained observable even after the participants' heading within the environment changed due to a body rotation, attenuating the effect of the front but not of the rear cue. The door and object cues both appeared to define boundaries of spatial categories when they were used for reorientation. This supports the idea that both types of cues can assist in environment-centered memory formation.

Medial temporal lobe volume predicts elders' everyday memory.

Deficits in memory for everyday activities are common complaints among healthy and demented older adults. The medial temporal lobes and dorsolateral prefrontal cortex are both affected by aging and early-stage Alzheimer's disease, and are known to influence performance on laboratory memory tasks. We investigated whether the volume of these structures predicts everyday memory. Cognitively healthy older adults and older adults with mild Alzheimer's-type dementia watched movies of everyday activities and completed memory tests on the activities. Structural MRI was used to measure brain volume. Medial temporal but not prefrontal volume strongly predicted subsequent memory. Everyday memory depends on segmenting activity into discrete events during perception, and medial temporal volume partially accounted for the relationship between performance on the memory tests and performance on an event-segmentation task. The everyday-memory measures used in this study involve retrieval of episodic and semantic information as well as working memory updating. Thus, the current findings suggest that during perception, the medial temporal lobes support the construction of event representations that determine subsequent memory.

Distraction shrinks space.

Research investigating how people remember the distance of paths they walk has shown two apparently conflicting effects of experience during encoding on subsequent distance judgments. By the feature accumulation effect, discrete path features such as turns, houses, or other landmarks cause an increase in remembered distance. By the distractor effect, performance of a concurrent task during path encoding causes a decrease in remembered distance. In this study, we ask the following: What are the conditions that determine whether the feature accumulation or the distractor effect dominates distortions of space? In two experiments, blindfolded participants were guided along two legs of a right triangle while reciting nonsense syllables. On some trials, one of the two legs contained features: horizontally mounted car antennas (gates) that bent out of the way as participants walked past. At the end of the second leg, participants either indicated the remembered path leg lengths using their hands in a ratio estimation task or attempted to walk, unguided, straight back to the beginning. In addition to response mode, visual access to the paths and time between encoding and response were manipulated to determine whether these factors would affect feature accumulation or distractor effects. Path legs with added features were remembered as shorter than those without, but this result was significant only in the haptic response mode data. This finding suggests that when people form spatial memory representations with the intention of navigating in room-scale spaces, interfering with information accumulation substantially distorts spatial memory.

Exploring the mental representation underlying familiarity assessment.

A new method was used to explore the role of perceptual information in familiarity-based recognition. The method uses a pairwise recognition task to compare recognition judgments to a test word when that word is related and unrelated to an immediately preceding word. If the false-alarm rate to the test word is greater when the two words are related, this is interpreted as reflecting an increase in the likelihood of positive familiarity assessment to the test word (Ngo, C. T., Sargent, J., & Dopkins, S. [2007]. Level of discrimination for recognition judgments reduced following the recognition of semantically related words. Journal of Memory and Language, 57, 415-436. doi:10.1016/j.jml.2007.05.007). The occurrence of such an increase for a given sort of preceding word-test word relatedness is taken as indicating that information of the sort in question is involved in familiarity-based recognition. Whereas previous work with this method has failed to find evidence that perceptual information is involved in familiarity-based recognition, the present study observed such evidence, under conditions in which previous work with other methods suggested that perceptual information would be likely to be involved in familiarity-based recognition. Thus, the study helped to validate the method and produced converging evidence that perceptual information is sometimes involved in familiarity-based recognition. The results of the study suggest that perceptual information is more likely to be involved in familiarity-based recognition when the lists for the recognition task are short.

Dynamic category structure in spatial memory.

This study examines bias (constant error) in spatial memory in an effort to determine whether this bias is defined by a dynamic egocentric reference frame that moves with the observer or by an environmentally fixed reference frame. Participants learned the locations of six target objects around them in a room, were blindfolded, and then rotated themselves to face particular response headings. From each response heading, participants used a pointer to indicate the remembered azimuthal locations of the objects. Analyses of the angular pointing errors showed a previously observed pattern of bias. More importantly, it appeared that this pattern of bias was defined relative to and moved with the observer--that is, was egocentric and dynamic. These results were interpreted in the framework of a modified category adjustment model as suggesting the existence of dynamic categorical (nonmetric) spatial codes.

Superficial Priming in Episodic Recognition.

We explored the effect of superficial priming in episodic recognition and found it to be different from the effect of semantic priming in episodic recognition. Participants made recognition judgments to pairs of items, with each pair consisting of a prime item and a test item. Correct positive responses to the test item were impeded if the prime and test item were superficially related; this was the case when the items were words and the crucial relationship was phonological and orthographic as well as when the items were letter strings and the crucial relationship was orthographic. The results of further experiments suggested that the priming effect cannot be attributed to a process of discounting or to habituation in a familiarity assessment process.

Chunking in spatial memory.

In order to gain insight into the nature of human spatial representations, the current study examined how those representations are affected by blind rotation. Evidence was sought on the possibility that whereas certain environmental aspects may be updated independently of one another, other aspects may be grouped (or chunked) together and updated as a unit. Participants learned the locations of an array of objects around them in a room, then were blindfolded and underwent a succession of passive, whole-body rotations. After each rotation, participants pointed to remembered target locations. Targets were located more precisely relative to each other if they were (a) separated by smaller angular distances, (b) contained within the same regularly configured arrangement, or (c) corresponded to parts of a common object. A hypothesis is presented describing the roles played by egocentric and allocentric information within the spatial updating system. Results are interpreted in terms of an existing neural systems model, elaborating the model's conceptualization of how parietal (egocentric) and medial temporal (allocentric) representations interact.

Effects of conceptual processing on familiarity-based recognition.

Two experiments compared the impact of conceptual and perceptual processing at encoding on the familiarity-based recognition of items without preexisting conceptual representations. The stimuli for the experiments were visual designs and nonsense letter strings. The process dissociation procedure was used in conjunction with the process dissociation equations and the Dual Process Signal Detection model to assess the contributions of familiarity-based recognition and recollection in the recognition of the stimuli. A conceptual processing advantage was observed in both experiments: familiarity-based recognition was enhanced more by conceptual than by perceptual processing at encoding. It is suggested that the results may be problematic for the view that conceptual priming underlies the conceptual processing advantage.

The bias for a recognition judgement depends on the response emitted in a prior recognition judgement.

On each trial of the experimental procedure the participant read a list of words and made successive recognition judgements to multiple test words. The bias for a given recognition judgement was more conservative if the judgement followed a correct positive response to a target than if it followed a correct negative response to a lure. Similar results were not observed for successive semantic recognition judgements. The bias shift was greater when the study list was short than when the list was long. The results suggest that participants in a recognition task have a sense of the size of the set of targets that might possibly be presented on the next trial and that, under conditions in which a word can only be presented once during the test phase, their bias becomes more conservative after a positive response to a target because the set is depleted.

Exploring the process of progressive disorientation.

While an increasing number of behavioral studies examining spatial cognition use experimental paradigms involving disorientation, the process by which one becomes disoriented is not well explored. The current study examined this process using a paradigm in which participants were blindfolded and underwent a succession of 70 degrees or 200 degrees passive, whole body rotations around a fixed vertical axis. After each rotation, participants used a pointer to indicate either their heading at the start of the most recent turn or their heading at the start of the current series of turns. Analyses showed that in both cases, mean pointing errors increased gradually over successive turns. In addition to the gradual loss of orientation indicated by this increase, analysis of the pointing errors also showed evidence of occasional, abrupt loss orientation. Results indicate multiple routes from an oriented to a disoriented state, and shed light on the process of becoming disoriented.