Does a concurrent motor process influence representational momentum?

Whether the direction of a hand motion that is congruent or incongruent with a concurrent target motion can influence representational momentum for that target was examined. Participants viewed a leftward or rightward moving target while moving their hand rightward, leftward, or not moving their hand. Prior studies of mental rotation found that congruency or incongruency of the direction of mental rotation and the direction of a concurrent physical rotation of a stimulus influenced mental rotation. As mental rotation and representational momentum each involve extrapolation of target motion, it could be predicted that congruency of the direction of hand motion and the direction of target motion might influence representational momentum of the target. Robust representational momentum occurred in all conditions, but there was no effect of congruency of hand motion and target motion, nor of the presence or absence of hand motion, on representational momentum. The results are consistent with a hypothesis that the generation of representational momentum involves sensory processes rather than motor processes.

Evaluation of GRCh38 and de novo haploid genome assemblies demonstrates the enduring quality of the reference assembly.

The human reference genome assembly plays a central role in nearly all aspects of today's basic and clinical research. GRCh38 is the first coordinate-changing assembly update since 2009; it reflects the resolution of roughly 1000 issues and encompasses modifications ranging from thousands of single base changes to megabase-scale path reorganizations, gap closures, and localization of previously orphaned sequences. We developed a new approach to sequence generation for targeted base updates and used data from new genome mapping technologies and single haplotype resources to identify and resolve larger assembly issues. For the first time, the reference assembly contains sequence-based representations for the centromeres. We also expanded the number of alternate loci to create a reference that provides a more robust representation of human population variation. We demonstrate that the updates render the reference an improved annotation substrate, alter read alignments in unchanged regions, and impact variant interpretation at clinically relevant loci. We additionally evaluated a collection of new de novo long-read haploid assemblies and conclude that although the new assemblies compare favorably to the reference with respect to continuity, error rate, and gene completeness, the reference still provides the best representation for complex genomic regions and coding sequences. We assert that the collected updates in GRCh38 make the newer assembly a more robust substrate for comprehensive analyses that will promote our understanding of human biology and advance our efforts to improve health.

Ear Advantage for Musical Location and Relative Pitch: Effects of Musical Training and Attention.

Trained musicians have been found to exhibit a right-ear advantage for high tones and a left-ear advantage for low tones. We investigated whether this right/high, left/low pattern of musical processing advantage exists in listeners who had varying levels of musical experience, and whether such a pattern might be modulated by attentional strategy. A dichotic listening paradigm was used in which different melodic sequences were presented to each ear, and listeners attended to (a) the left ear or the right ear or (b) the higher pitched tones or the lower pitched tones. Listeners judged whether tone-to-tone transitions within each melodic sequence moved upward or downward in pitch. Only musically experienced listeners could adequately judge the direction of successive pitch transitions when attending to a specific ear; however, all listeners could judge the direction of successive pitch transitions within a high-tone stream or a low-tone stream. Overall, listeners exhibited greater accuracy when attending to relatively higher pitches, but there was no evidence to support a right/high, left/low bias. Results were consistent with effects of attentional strategy rather than an ear advantage for high or low tones. Implications for a potential performer/audience paradox in listening space are considered.

Displacement of location in illusory line motion.

Six experiments examined displacement in memory for the location of the line in illusory line motion (ILM; appearance or disappearance of a stationary cue is followed by appearance of a stationary line that is presented all at once, but the stationary line is perceived to "unfold" or "be drawn" from the end closest to the cue to the end most distant from the cue). If ILM was induced by having a single cue appear, then memory for the location of the line was displaced toward the cue, and displacement was larger if the line was closer to the cue. If ILM was induced by having one of two previously visible cues vanish, then memory for the location of the line was displaced away from the cue that vanished. In general, the magnitude of displacement increased and then decreased as retention interval increased from 50 to 250 ms and from 250 to 450 ms, respectively. Displacement of the line (a) is consistent with a combination of a spatial averaging of the locations of the cue and the line with a relatively weaker dynamic in the direction of illusory motion, (b) might be implemented in a spreading activation network similar to networks previously suggested to implement displacement resulting from implied or apparent motion, and (c) provides constraints and challenges for theories of ILM.

The possibility of an impetus heuristic.

Evidence consistent with a belief in impetus is drawn from studies of naïve physics, perception of causality, perception of force, and representational momentum, and the possibility of an impetus heuristic is discussed. An impetus heuristic suggests the motion path of an object that was previously constrained or influenced by an external source (e.g., object, force) appears to exhibit the same constraint or influence even after that constraint or influence is removed. Impetus is not a valid physical principle, but use of an impetus heuristic can in some circumstances provide approximately correct predictions regarding future object motion, and such predictions require less cognitive effort and resources than would predictions based upon objective physical principles. The relationship of an impetus heuristic to naïve impetus theory and to objective physical principles is discussed, and use of an impetus heuristic significantly challenges claims that causality or force can be visually perceived. Alternatives to an impetus heuristic are considered, and potential boundary conditions and falsification of the impetus notion are discussed. Overall, use of an impetus heuristic offers a parsimonious explanation for findings across a wide range of perceptual domains and could potentially be extended to more metaphorical types of motion.

Representational gravity: Empirical findings and theoretical implications.

Judgment of the location of a previously viewed moving or stationary target is often displaced in the direction of implied gravitational attraction, and this has been referred to as representational gravity. Variables that have been investigated for a possible influence on representational gravity include characteristics of the target (size/mass, velocity, distance traveled, orientation, modality), display (retention interval, response measure, height in the picture plane), context (nontarget intramodal stimuli, cross-modal components of a single stimulus), and observer (oculomotor behavior, body orientation, psychopathology), and several additional variables that might influence representational gravity but have not yet been investigated are suggested for future studies. Conclusions and speculations regarding the contribution and relationship of representational gravity to several variables, processes, and tasks (physical gravity, linear acceleration, subjective visual vertical, size/mass and weight, other biases in spatial localization, catching and intercepting a moving target, an internal model of gravity, naïve physics, a gravity heuristic, art and aesthetics) are discussed, and compatibility of representational gravity with Gibsonian and representational approaches is noted. It is suggested that representational gravity is an important adaptation that aids observers in interactions with physical objects in the environment, but that such an adaptation is not necessarily fully consistent with objective physical principles.

Effects of spatial cueing on representational momentum.

Effects of a spatial cue on representational momentum were examined. If a cue was present during or after target motion and indicated the location at which the target would vanish or had vanished, forward displacement of that target decreased. The decrease in forward displacement was larger when cues were present after target motion than when cues were present during target motion. If a cue was present during target motion, high-relevant cues (that indicated the final location of the target) led to larger decreases in forward displacement than did low-relevant cues (that indicated only the horizontal coordinate of the final location of the target). If a cue was present after target motion, there was a trend for low-relevant cues to lead to larger decreases in forward displacement than did high-relevant cues. Possible explanations involving displacement of the cue or landmark attraction are considered. Implications for the relationship of attention and representational momentum, and for whether representational momentum reflects an automatic process, are discussed.

Representational momentum is not (totally) impervious to error feedback.

The influence of feedback on representational momentum for the final location of a moving target was examined in 3 experiments. The presence of binary feedback (correct, error) during practise trials or during larger blocks of experimental trials did not reduce representational momentum, nor did the presence of more informative feedback specifying the direction of error (error-in front of, error-behind) during larger blocks of experimental trials reduce representational momentum. Effects on representational momentum of whether feedback was consistently provided were inconsistent. Even though feedback did not reduce representational momentum per se, feedback did influence the probability of a same response for different probe positions. Implications of the data for R. A. Finke and J. J. Freyd's (1985; J. J. Freyd, 1987) claim that representational momentum is impervious to error feedback, and possible roles of perceptual learning in representational momentum, are discussed.

Momentum-like effects and the dynamics of perception, cognition, and action.

In a momentum-like effect, the likely future state of a current action or process is extrapolated. Momentum-like effects have been suggested to reflect dynamic processes, but such effects have not often been discussed in the broader literature on dynamic approaches to perception, cognition, and action. Several momentum-like effects are briefly described, and attempts to formulate dynamic theories of such effects are considered. Issues regarding dynamic representation that are relevant for theories of momentum-like effects (whether contingencies are invariant, stochastic, or arbitrary; bridging gaps between perception and action and between action and reinforcement; adaptiveness of such effects; influences of an observer's knowledge, beliefs, and expectations; relationship of momentum-like effects to naïve physics and perception of causality) are discussed. Issues highlighted by a consideration of momentum-like effects relevant for dynamic approaches to other phenomena (multiple meanings and senses of "dynamic," different meanings and connotations of "continuation" and "extrapolation," perceptual inference of subjective or objective consequences, importance of time scale and temporal information, importance of the computational theory level, momentum-like effects as an example of predictive processing) are also discussed. Momentum-like effects provide examples of relatively simple dynamic processes that reveal and highlight issues relevant for study of dynamic approaches in a wide range of perceptual, cognitive, and action phenomena.

A principal components analysis of dynamic spatial memory biases.

Research has shown that spatial memory for moving targets is often biased in the direction of implied momentum and implied gravity, suggesting that representations of the subjective experiences of these physical principles contribute to such biases. The present study examined the association between these spatial memory biases. Observers viewed targets that moved horizontally from left to right before disappearing or viewed briefly shown stationary targets. After a target disappeared, observers indicated the vanishing position of the target. Principal components analysis revealed that biases along the horizontal axis of motion loaded on separate components from biases along the vertical axis orthogonal to motion. The findings support the hypothesis that implied momentum and implied gravity biases have unique influences on spatial memory.

Does Allocation of Attention Influence Relative Velocity and Strength of Illusory Line Motion?

In illusory line motion, presentation of a cue is followed by presentation of a nearby stationary line, and the line is perceived to "unfold," "expand," or "extend" away from the cue. Effects of the allocation of attention regarding where the cue or the line would be presented were measured in three experiments, and ratings of relative velocity and relative strength of illusory motion were collected. Findings included (a) relative velocity and relative strength decreased with increases in SOA from 50 to 450 ms, (b) relative velocity and relative strength were not influenced by whether illusory motion moved from one end of the line to the other or from both ends toward the middle of the line, (c) increased uncertainty regarding where the line would appear did not influence relative velocity or relative strength, and (d) valid pre-cues regarding the location of a cue resulted in faster relative velocity than did invalid pre-cues, but pre-cue validity did not influence relative strength. Implications of these findings for the relationship of such illusory motion and attention (e.g., divided attention, shifts in attended location) are considered.

Representational momentum and anisotropies in nearby visual space.

The possibility of anisotropies in visual space in and near the final location of a moving target was examined. Experiments 1 and 2 presented a moving target, and after the target vanished, participants indicated the final location of the leading or trailing edge of the target. Memory for both edges was displaced forward from the actual final locations, and the magnitude of displacement was smaller for the leading edge. Experiments 3 and 4 also presented stationary objects in front of and behind the final location of the target, and participants indicated the location of the nearest or farthest edge of one of the stationary objects. Memory for the near or far edge of an object in front of the target was displaced backward, and memory for the near or far edge of an object behind the target was displaced forward; the magnitude of displacement was larger for objects in front of the target and when the edge was farther away. The findings (a) suggest representational momentum is associated with an anisotropy of visual space that extends across and outward from the moving target and (b) are consistent with previous findings regarding estimation of time-to-contact, anorthoscopic perception, and memory psychophysics.

Toward a general theory of momentum-like effects.

The future actions, behaviors, and outcomes of objects, individuals, and processes can often be anticipated, and some of these anticipations have been hypothesized to result from momentum-like effects. Five types of momentum-like effects (representational momentum, operational momentum, attentional momentum, behavioral momentum, psychological momentum) are briefly described. Potential similarities involving properties of momentum-like effects (continuation, coherence, role of chance or guessing, role of sensory processing, imperviousness to practice or error feedback, shifts in memory for position, effects of changes in velocity, rapid occurrence, effects of retention interval, attachment to an object rather than an abstract frame of reference, nonrigid transformation) are described, and potential constraints on a future theory of momentum-like effects (dynamic representation, nature of extrapolation, sensitivity to environmental contingencies, bridging gaps between stimulus and response, increasing adaptiveness to the environment, serving as a heuristic for perception and action, insensitivity to stimulus format, importance of subjective consequences, role of knowledge and belief, automaticity of occurrence, properties of functional architecture) are discussed. The similarity and ubiquity of momentum-like effects suggests such effects might result from a single or small number of mechanisms that operate over different dimensions, modalities, and time-scales and provide a fundamental adaptation for perception and action.

Perceived causality, force, and resistance in the absence of launching.

In the launching effect, a moving object (the launcher) contacts a stationary object (the target), and upon contact, the launcher stops and the target begins moving in the same direction and at the same or slower velocity as previous launcher motion (Michotte, 1946/1963). In the study reported here, participants viewed a modified launching effect display in which the launcher stopped before or at the moment of contact and the target remained stationary. Participants rated perceived causality, perceived force, and perceived resistance of the launcher on the target or the target on the launcher. For launchers and for targets, increases in the size of the spatial gap between the final location of the launcher and the location of the target decreased ratings of perceived causality and ratings of perceived force and increased ratings of perceived resistance. Perceived causality, perceived force, and perceived resistance exhibited gradients or fields extending from the launcher and from the target and were not dependent upon contact of the launcher and target. Causal asymmetries and force asymmetries reported in previous studies did not occur, and this suggests that such asymmetries might be limited to typical launching effect stimuli. Deviations from Newton's laws of motion are noted, and the existence of separate radii of action extending from the launcher and from the target is suggested.

Representational momentum and related displacements in spatial memory: A review of the findings.

Memory for the final location of a moving target is often displaced in the direction of target motion, and this has been referred to as representational momentum. Characteristics of the target (e.g., velocity, size, direction, and identity), display (e.g., target format, retention interval, and response method), context (landmarks, expectations, and attribution of motion source), and observer (e.g., allocation of attention, eye movements, and psychopathology) that influence the direction and magnitude of displacement are reviewed. Specific conclusions regarding numerous variables that influence displacement (e.g., presence of landmarks or surrounding context), as well as broad-based conclusions regarding displacement in general (e.g., displacement does not reflect objective physical principles, may reflect aspects of naive physics, does not solely reflect eye movements, may involve some modular processing, and reflects high-level processes) are drawn. A possible computational theory of displacement is suggested in which displacement (1) helps bridge the gap between perception and action and (2) plays a critical part in localizing stimuli in the environment.

The varieties of momentum-like experience.

Cognition and behavior exhibit biases consistent with future expectations, and some of these biases result in momentum-like effects and have been linked with the idea of momentum. These momentum-like effects include representational momentum, operational momentum, attentional momentum, behavioral momentum, and psychological momentum. Effects of numerous variables involving characteristics of the target, display, context, or observer on each momentum-like effect are considered, and similarities of different momentum-like effects are considered. It is suggested that representational momentum, operational momentum, and attentional momentum reflect similar or overlapping mechanisms based on a perceptual time-scale and extrapolation primarily across space, and that behavioral momentum and psychological momentum reflect similar or overlapping mechanisms based on a longer time-scale and extrapolation primarily across time. It is further suggested that all 5 forms of momentum-like effect could reflect a more general extrapolation mechanism that anticipates the future action, behavior, or outcome of a given target, person, or process. A list of properties characterizing momentum-like effects is proposed, and constraints and issues relevant to future models of momentum-like effects are discussed. (PsycINFO Database Record

Does representational momentum reflect a distortion of the length or the endpoint of a trajectory?

Observers viewed a moving target, and after the target vanished, indicated either the initial position or the final position of the target. In Experiment 1, an auditory tone cued observers to indicate either the initial position or the final position; in Experiment 2, different groups of observers indicated the initial position or the final position. Judgments of the initial position were displaced backward in the direction opposite to motion, and judgments of the final position were displaced forward in the direction of motion. The data suggest that the remembered trajectory is longer than the actual trajectory, and the displacement pattern is not consistent with the hypothesis that representational momentum results from a distortion of memory for the location of a trajectory.

The flash-lag effect and related mislocalizations: findings, properties, and theories.

If an observer sees a flashed (briefly presented) object that is aligned with a moving target, the perceived position of the flashed object usually lags the perceived position of the moving target. This has been referred to as the flash-lag effect, and the flash-lag effect has been suggested to reflect how an observer compensates for delays in perception that are due to neural processing times and is thus able to interact with dynamic stimuli in real time. Characteristics of the stimulus and of the observer that influence the flash-lag effect are reviewed, and the sensitivity or robustness of the flash-lag effect to numerous variables is discussed. Properties of the flash-lag effect and how the flash-lag effect might be related to several other perceptual and cognitive processes and phenomena are considered. Unresolved empirical issues are noted. Theories of the flash-lag effect are reviewed, and evidence inconsistent with each theory is noted. The flash-lag effect appears to involve low-level perceptual processes and high-level cognitive processes, reflects the operation of multiple mechanisms, occurs in numerous stimulus dimensions, and occurs within and across multiple modalities. It is suggested that the flash-lag effect derives from more basic mislocalizations of the moving target or flashed object and that understanding and analysis of the flash-lag effect should focus on these more basic mislocalizations rather than on the relationship between the moving target and the flashed object.

Forms of momentum across space: representational, operational, and attentional.

Cognition can exhibit biases consistent with future expectations, and some of these biases result in momentum-like effects and have been linked with the idea of an internalization of the effects of momentum. These momentum-like effects include representational momentum, operational momentum, and attentional momentum. Similarities and differences between these different momentum-like effects are considered. Hubbard's (2005) review of representational momentum is updated to include studies published since that review appeared, and the first full reviews of operational momentum and attentional momentum are provided. It is suggested that (1) many variables that influence one of these momentum-like effects have a similar influence on another momentum-like effect, (2) representational momentum, operational momentum, and attentional momentum reflect similar or overlapping mechanisms, and operational momentum and attentional momentum are special cases of representational momentum, and (3) representational momentum, operational momentum, and attentional momentum reflect properties of a more general spatial representation in which change or transformation of a stimulus is mapped onto motion in a spatial coordinate system.