Effects of task type on spontaneous alternations of attentional states.

Mind wandering is a common occurrence that can have serious consequences, but estimating when mind wandering occurs is a challenging research question. Previous research has shown that during meditation, people may spontaneously alternate between task-oriented and mind-wandering states without awareness (Zukosky & Wang, 2021, Cognition, 212, Article 104689). However, under what conditions such alternations occur is not clear. The present study examined the effects of task type on spontaneous alternations between task focus and mind wandering. In addition to a meditation task, participants performed either a scene-categorization-based CPT or a visual detection task while attentional orientation was assessed via self-monitoring and intermittent probes. The three tasks differ in the extent of their reliance on continuous monitoring (less required in the detection than meditation and CPT tasks) and attentional orientation (oriented internally in meditation task and externally in CPT and detection tasks). To overcome prior methodological challenges, we applied a technique designed to detect spontaneous alternations between focused and mind-wandering states without awareness, based on how the proportion of "focused" responses/ratings to intermittent probes changes during a focus-to-mind-wandering interval (i.e., the period from one self-report of mind wandering to the subsequent self-report). Our results showed that the proportion of "focused" responses to intermittent probes remained constant with increasing interprobe interval during meditation (consistent with previous work), but declined significantly in the CPT and detection tasks. These findings support the hypothesis that spontaneous alternations of attentional states without self-awareness occur during tasks emphasizing internally but not externally oriented attention.

Effects of rhythmic auditory stimulation on vision: Oscillations in performance can be enhanced, but not induced.

A variety of reports suggest that rhythmic auditory stimulation can entrain visual perception, inducing perceptual oscillations as a function of time relative to the auditory rhythm. These effects have, to date, been reported only for stimulation frequencies at and below 3 Hz. Here we investigate the effects of rhythmic auditory stimulation on the detection of masked visual targets when this stimulation occurs at frequencies to which the visual system has been shown to entrain (8-12 Hz). Across four experiments, we found no consistent evidence of poststimulation modulations in performance induced by 8.5, 10.6, or 12.1 Hz auditory stimulation. This absence of a consistent auditory-to-visual effect was paralleled by an absence of unimodal effects (oscillations in auditory performance) following 12.1 Hz auditory stimulation. In a fifth experiment, we found that although auditory stimulation alone did not induce oscillations in visual performance, auditory stimulation did enhance the effects of concurrent visual stimulation. Notably, this enhancement did not require synchronous presentation of stimuli. These observations are consistent with recent reports that passive auditory stimulation beyond 5 Hz induces neither auditory perceptual oscillations nor visual cortical oscillations and suggest limits to the extent of cross-modal entrainment. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Preference for prior probabilities of positions under incongruent visual information.

People's expectations help them make judgments about the world. In the area of spatial memory, the interaction of existing knowledge with incoming information is best illustrated in the category effect, a bias in positioning a target toward the prototypical location of its region (Huttenlocher et al., 1991). According to Bayesian principles, these biased judgments are weighted averages of a target's metric code (incoming data) and spatial categorical code (prior expectation). While previous research in the category effect generally focused on presence and reliability of different sources of information, we examined a scenario in which prior expectation is violated. Specifically, we investigated the role of prior expectations in location memory when these conflict with visual perception. We found that people favored their previous knowledge about where a target ought to be over the visual data on the actual target location. Hence, our work contributes to the literature by demonstrating the dominance of prior expectations over incongruent visual cues, and the data extend the context effect to spatial memory. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Human navigation in curved spaces.

Navigation and representations of the spatial environment are central to human survival. It has often been debated whether spatial representations follow Euclidean principles, and a number of studies challenged the Euclidean hypothesis. Two experiments examined the geometry of human navigation system using true non-Euclidean environments, i.e., curved spaces with non-Euclidean geometry at every point of the space. Participants walked along two legs in an outbound journey, then pointed to the direction of the starting point (home). The homing behavior was examined in three virtual environments, Euclidean space, hyperbolic space, and spherical space. The results showed that people's responses matched the direction of Euclidean origin, regardless of the curvature of the space itself. Moreover, participants still responded as if the space were Euclidean when a learning period was added for them to explore the spatial properties of the environment before performing the homing task to ensure violations of Euclidean geometry were readily detected. These data suggest that the path integration / spatial updating system operates on Euclidean geometry, even when curvature violations are clearly present.

Spontaneous state alternations in the time course of mind wandering.

It's a common assumption that people's mental state timeline can be divided into a sequence of focus-mind wandering episodes, each comprises a focusing stage followed by a mind wandering stage. Accordingly, probability of being in a focus state should be high early in an episode and decrease overtime. We investigated the dynamics of shifting between meditation and off task thoughts by systematically probing participants at various time points during a focus-mind wandering episode. Contrary to predictions of the two-stage model, there's no significant decrease in probability of focus state during a focus-mind wandering episode. Simulations matching parameters of each participant suggest that the lack of this negative trend was not due to statistical power. Instead, people may have multiple spontaneous alternations between meditation and off task thoughts before they are able to catch themselves mind wandering. Based on this Multiple Sub-event Model, a novel method was developed to estimate the number of sub-events during a focus-mind wandering episode.

Assessing Postural Instability and Cybersickness Through Linear and Angular Displacement.

OBJECTIVE: To examine the hypothesis that constant speed is more comfortable than variable speed profiles and may minimize cybersickness. BACKGROUND: Current best practices for virtual reality (VR) content creation suggest keeping any form of acceleration as short and infrequent as possible to mitigate cybersickness. METHODS: In Experiment 1, participants experienced repetitions of simulated linear motion, and in Experiment 2, they experienced repetitions of a circular motion. Three speed profiles were tested in each experiment. Each trial lasted 2 min while standing. Cybersickness was measured using the Simulator Sickness Questionnaire (SSQ) and operationally defined in terms of total severity scores. Postural stability was measured using a Wii Balance Board and operationally defined in terms of center of pressure (COP) path length. Postural measures were decomposed into anterior-posterior and medial-lateral axes and subjected to detrended fluctuation analysis. RESULTS: For both experiments, no significant differences were observed between the three speed profiles in terms of cybersickness or postural stability, and none of the baseline postural measures could predict SSQ scores for the speed profile conditions. An axis effect was observed in both experiments such that normalized COP movement was significantly greater along the anterior-posterior axis than the medial-lateral axis. CONCLUSION: Results showed no convincing evidence to support the common belief that constant speed is more comfortable than variable speed profiles for scenarios typical of VR applications. APPLICATION: The present findings offer guidelines for the design of locomotion techniques involving traversal in VR environments.

Bayesian average or truncation at boundaries? The mechanisms underlying categorical bias in spatial memory.

Spatial memory is often biased by various factors, such as the region a target belongs to, which can be defined based on physical, perceptual, or implicit boundaries. In the typical dot-localization task first introduced by Huttenlocher, Hedges, and Duncan (Psychological Review 98: 352-376, 1991), individuals normally divide the task space into four quadrants delineated at the Cartesian axes (forming "default categories") and show systematic bias in target localization toward the center of the category. At least two mechanisms have been proposed to account for these categorical biases, namely (a) weighted-average of a metric representation and the category prototype representation and (b) truncation of an un-biased metric representation at the category boundary. Both models can account for these findings and cannot be differentiated by existing research methods. Using a new distribution analysis, the current study sought to differentiate between these two models. Participants viewed a dot inside a circle and recalled its location after a delay either with the same blank circle (i.e., the standard dot-in-circle paradigm) or when an alternative V-shaped category boundary was visually presented at retrieval. The data from three experiments showed symmetrical distribution of the errors that shifted toward the category center when people primarily used the default category, supporting the weighted-average model. In contrast, when people primarily used the alternative category, the errors showed a highly skewed distribution, more consistent with the truncation model. Overall, these results provided the first experimental evidence for both mechanisms separately.

A new approach to differentiate states of mind wandering: Effects of working memory capacity.

Although widely studied, the process of how mind wandering occurs and is subsequently sustained still remains unclear. Moreover, the traditional concept of mind wandering tendency/frequency based on the self- or probe-caught methods alone is incoherent and problematic. We developed a new approach to characterize the mind wandering process by combining the self-caught and probe-caught methods to estimate the time of focus and time of mind wandering separately, and examined their relationship to working memory capacity. Participants performed an OSPAN task and subsequently a basic Mindfulness Meditation Task (focus on breath). During the meditation task, participants indicated when they became aware that they were mind wandering (self-caught method), or were asked if they were mind wandering when probed (probe-caught method). Results showed that time of focus but not time of mind wandering increased with greater working memory capacity. This suggests that individuals with higher working memory capacity were able to focus on the current task longer, but had little effect on the ability to monitor and terminate mind wandering once it occurred. The theoretical and methodological implications of this new approach are discussed.

Measuring temporal summation in visual detection with a single-photon source.

Temporal summation is an important feature of the visual system which combines visual signals that arrive at different times. Previous research estimated complete summation to last for 100ms for stimuli judged "just detectable." We measured the full range of temporal summation for much weaker stimuli using a new paradigm and a novel light source, developed in the field of quantum optics for generating small numbers of photons with precise timing characteristics and reduced variance in photon number. Dark-adapted participants judged whether a light was presented to the left or right of their fixation in each trial. In Experiment 1, stimuli contained a stream of photons delivered at a constant rate while the duration was systematically varied. Accuracy should increase with duration as long as the later photons can be integrated with the proceeding ones into a single signal. The temporal integration window was estimated as the point that performance no longer improved, and was found to be 650ms on average. In Experiment 2, the duration of the visual stimuli was kept short (100ms or <30ms) while the number of photons was varied to explore the efficiency of summation over the integration window compared to Experiment 1. There was some indication that temporal summation remains efficient over the integration window, although there is variation between individuals. The relatively long integration window measured in this study may be relevant to studies of the absolute visual threshold, i.e., tests of single-photon vision, where "single" photons should be separated by greater than the integration window to avoid summation.

The cause of category-based distortions in spatial memory: A distribution analysis.

Recall of remembered locations reliably reflects a compromise between a target's true position and its region's prototypical position. The effect is quite robust, and a standard interpretation for these data is that the metric and categorical codings blend in a Bayesian combinatory fashion. However, there has been no direct experimental evidence that the 2 codings are actually combined. That is, at least 2 mechanisms can produce biased mean responses: (a) people may in fact take a weighted average of the metric and categorical representations, but (b) these 2 codings may instead compete for response, each winning with a certain probability. The present work investigated these 2 hypotheses for the cause of category-based distortions using a new distribution analysis. Participants viewed a target within a blank circle and reproduced its location after a short delay. The error data for individual participants were fit with a kernel curve, which provides a distribution without the assumption of normality. Almost all individual distributions displayed a clear biased main peak, indicating a weighted average between the representations, not an alteration between the 2 representations. (PsycINFO Database Record

Building a cognitive map by assembling multiple path integration systems.

Path integration and cognitive mapping are two of the most important mechanisms for navigation. Path integration is a primitive navigation system which computes a homing vector based on an animal's self-motion estimation, while cognitive map is an advanced spatial representation containing richer spatial information about the environment that is persistent and can be used to guide flexible navigation to multiple locations. Most theories of navigation conceptualize them as two distinctive, independent mechanisms, although the path integration system may provide useful information for the integration of cognitive maps. This paper demonstrates a fundamentally different scenario, where a cognitive map is constructed in three simple steps by assembling multiple path integrators and extending their basic features. The fact that a collection of path integration systems can be turned into a cognitive map suggests the possibility that cognitive maps may have evolved directly from the path integration system.

Listeners use speaker identity to access representations of spatial perspective during online language comprehension.

Little is known about how listeners represent another person's spatial perspective during language processing (e.g., two people looking at a map from different angles). Can listeners use contextual cues such as speaker identity to access a representation of the interlocutor's spatial perspective? In two eye-tracking experiments, participants received auditory instructions to move objects around a screen from two randomly alternating spatial perspectives (45° vs. 315° or 135° vs. 225° rotations from the participant's viewpoint). Instructions were spoken either by one voice, where the speaker's perspective switched at random, or by two voices, where each speaker maintained one perspective. Analysis of participant eye-gaze showed that interpretation of the instructions improved when each viewpoint was associated with a different voice. These findings demonstrate that listeners can learn mappings between individual talkers and viewpoints, and use these mappings to guide online language processing.

Examining reference frame interaction in spatial memory using a distribution analysis.

Previous research showed competition among reference frames in spatial attention and language. The present studies developed a new distribution analysis to examine reference frame interactions in spatial memory. Participants viewed virtual arrays of colored pegs and were instructed to remember them either from their own perspective or from the perspective aligned with the rectangular floor. Then they made judgments of relative directions from their respective encoding orientation. Those taking the floor-axis perspective showed systematic bias in the signed errors toward their egocentric perspective, while those taking their own perspective showed no systematic bias, both for random and symmetrical object arrays. The bias toward the egocentric perspective was observed when learning a real symmetric regular object array with strong environmental cues for the aligned axis. These results indicate automatic processing of the self reference while taking the floor-axis perspective but not vice versa, and suggest that research on spatial memory needs to consider the implications of competition effects in reference frame use.

Differentiating spatial memory from spatial transformations.

The perspective-taking task is one of the most common paradigms used to study the nature of spatial memory, and better performance for certain orientations is generally interpreted as evidence of spatial representations using these reference directions. However, performance advantages can also result from the relative ease in certain transformations/rotations. To differentiate spatial memory from spatial transformations, the present study took a new approach based on the hypothesis that responses may be biased toward the original representation but not a transformed one. Participants memorized a regular target array and then judged the relative direction between 2 targets while imagining facing various directions. Their response time and absolute errors showed the standard advantages at 4 imagined orientations. In contrast, an attraction analysis suggested that only 1 orientation was represented in memory, whereas performance advantages at other orthogonal orientations were due to lower transformation costs and should not be interpreted as spatial representations. These findings challenged the traditional performance-based interpretations of perspective change tasks and provided a new research paradigm to differentiate spatial representations from spatial transformations.

What counts as the evidence for three-dimensional and four-dimensional spatial representations?

The dimension of spatial representations can be assessed by above-chance performance in novel shortcut or spatial reasoning tasks independent of accuracy levels, systematic biases, mosaic/segmentation across space, separate coding of individual dimensions, and reference frames. Based on this criterion, humans and some other animals exhibited sufficient evidence for the existence of three-dimensional and/or four-dimensional spatial representations.

Theories of spatial representations and reference frames: what can configuration errors tell us?

The issue of reference frame is central to theories of spatial representations. Various classifications have been made for different types of reference frames, along with prototypical research paradigms to distinguish between them. This article focuses on the configuration error paradigm proposed by Wang and Spelke (Cognition 77:215-250, 2000) that has been used to examine the nature of the spatial representations underlying object localization during self-movement. Three basic models of spatial memory and spatial updating are discussed, as well as the assumptions behind the configuration error paradigm, to distinguish between static representations, such as the traditional allocentric cognitive map and the egocentric snapshots, and dynamic representations, such as the egocentric updating system. Recent experimental findings are reexamined and shown to be consistent with multiple models, among which the egocentric-updating-and-reload model with an enduring egocentric component provides the simplest interpretations.

The effect of landmarks in human path integration.

The effect of landmarks in human path integration was investigated using virtual hallway-mazes. Participants traveled along random 5-segment paths either with or without distinctive landmarks at some segment intersections. They were required to directly return to the origin or to one of the landmark locations from the end of the path. Results showed that knowledge of the return targets prior to the outbound trip significantly reduced RTs to both the origin and the landmarks. Moreover, RTs in the return-to-origin trials were longer with landmarks present than without landmarks. This effect was eliminated when the return target was given prior to the trip. These results suggest that processing of the origin and the landmarks interfere with each other. However this interference is not obligatory and can be eliminated or reduced by prior knowledge about the target. The influences of landmarks on path integration and spatial updating were discussed.

Overcoming default categorical bias in spatial memory.

In the present study, we investigated whether a strong default categorical bias can be overcome in spatial memory by using alternative membership information. In three experiments, we tested location memory in a circular space while providing participants with an alternative categorization. We found that visual presentation of the boundaries of the alternative categories (Experiment 1) did not induce the use of the alternative categories in estimation. In contrast, visual cuing of the alternative category membership of a target (Experiment 2) and unique target feature information associated with each alternative category (Experiment 3) successfully led to the use of the alternative categories in estimation. Taken together, the results indicate that default categorical bias in spatial memory can be overcome when appropriate cues are provided. We discuss how these findings expand the category adjustment model (Huttenlocher, Hedges, & Duncan, 1991) in spatial memory by proposing a retrieval-based category adjustment (RCA) model.

The effect of active selection in human path integration.

Path integration refers to the ability to integrate self-motion information to estimate one's current position and orientation relative to the origin. To investigate the effect of active selection in path integration, we used a virtual homing task in which participants traveled along hallways and attempted to directly return to the origin. Two groups of participants differed in the voluntary selection of the path structure, but received the same perceptual and motor information. Information about distance traveled was purely visual via optic flow, whereas turnings were specified both visually and through body senses. The active group made free (Experiment 1) or forced (Experiment 2) selections to determine the structure of the outbound path, whereas the passive group followed these outbound paths. We found no facilitation effects of the active selection on homing performance, suggesting that humans' limited path integration abilities cannot be attributed to the nature of the task.

A landmark effect in the perceived displacement of objects.

Perceiving the displacement of an object after a visual distraction is an essential ability to interact with the world. Previous research has shown a bias to perceive the first object seen after a saccade as stable while the second one moving (landmark effect). The present study examines the generality and nature of this phenomenon. The landmark effect was observed in the absence of eye movements, when the two objects were obscured by a blank screen, a moving-pattern mask, or simply disappeared briefly before reappearing one after the other. The first reappearing object was not required to remain visible while the second object reappeared to induce the bias. The perceived direction of the displacement was mainly determined by the relative displacement of the two objects, suggesting that the landmark effect is primarily due to a landmark calibration mechanism.