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I-Perception 2022A task-irrelevant, amplitude-modulating sound influences perception of a size-modulating visual stimulus. To probe the limits of this audiovisual interaction we vary the...
A task-irrelevant, amplitude-modulating sound influences perception of a size-modulating visual stimulus. To probe the limits of this audiovisual interaction we vary the second temporal derivative of object size and of sound amplitude. In the study's first phase subjects see a visual stimulus size-modulating with 0, 0, or <0, and judge each one's rate as increasing, constant, or decreasing. Visual stimuli are accompanied by a steady, non-modulated auditory stimulus. The novel combination of multiple stimuli and multi-alternative responses allows subjects' similarity space to be estimated from the stimulus-response confusion matrix. In the study's second phase, rate-varying visual stimuli are presented in concert with auditory stimuli whose second derivative also varied. Subjects identified each visual stimuli as one of the three types, while trying to ignore the accompanying sound. Unlike some previous results with fixed at 0, performance benefits relatively little when visual and auditory stimuli share the same directional change in modulation. However, performance does drop when visual and auditory stimului differ in their directions of rate change. Our task's computational demands may make it particularly vulnerable to the effects of a dynamic task-irrelevant stimulus.
PubMed: 36467124
DOI: 10.1177/20416695221116653 -
PloS One 2021Recent studies have suggested that people's intent and ability to act also can influence their perception of their bodies' peripersonal space. Vice versa one could...
Recent studies have suggested that people's intent and ability to act also can influence their perception of their bodies' peripersonal space. Vice versa one could assume that the inability to reach toward and grasp an object might have an impact on the subject's perception of reaching distance. Here we tested this prediction by investigating body size and action capability perception of neurological patients suffering from arm paresis after stroke, comparing 32 right-brain-damaged patients (13 with left-sided arm paresis without additional spatial neglect, 10 with left-sided arm paresis and additional spatial neglect, 9 patients had neither arm paresis nor neglect) and 27 healthy controls. Nineteen of the group of right hemisphere stroke patients could be re-examined about five months after initial injury. Arm length was estimated in three different methodological approaches: explicit visual, explicit tactile/proprioceptive, and implicit reaching. Results fulfilled the working hypothesis. Patients with an arm paresis indeed perceived their bodies differently. We found a transient overestimation of the length of the contralesional, paretic arm after stroke. Body size and action capability perception for the extremities thus indeed seem to be tightly linked in humans.
Topics: Aged; Arm; Body Size; Case-Control Studies; Female; Humans; Male; Middle Aged; Paresis; Proprioception; Size Perception; Stroke
PubMed: 34086777
DOI: 10.1371/journal.pone.0252596 -
Nature Neuroscience Feb 2020The entorhinal cortex contains neurons that represent self-location, including grid cells that fire in periodic locations and velocity signals that encode running speed...
The entorhinal cortex contains neurons that represent self-location, including grid cells that fire in periodic locations and velocity signals that encode running speed and head direction. Although the size and shape of the environment influence grid patterns, whether entorhinal velocity signals are equally influenced or provide a universal metric for self-motion across environments remains unknown. Here we report that speed cells rescale after changes to the size and shape of the environment. Moreover, head direction cells reorganize in an experience-dependent manner to align with the axis of environmental change. A knockout mouse model allows dissociation of the coordination between cell types, with grid and speed cells, but not head direction cells, responding in concert to environmental change. These results point to malleability in the coding features of multiple entorhinal cell types and have implications for which cell types contribute to the velocity signal used by computational models of grid cells.
Topics: Animals; Computer Simulation; Entorhinal Cortex; Grid Cells; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Models, Neurological; Space Perception; Spatial Navigation
PubMed: 31932764
DOI: 10.1038/s41593-019-0562-5 -
Frontiers in Neurorobotics 2020In perceptual psychology, estimations of visual depth and size under different spatial layouts have been extensively studied. However, research evidence in virtual...
In perceptual psychology, estimations of visual depth and size under different spatial layouts have been extensively studied. However, research evidence in virtual environments (VE) is relatively lacking. The emergence of human-computer interaction (HCI) and virtual reality (VR) has raised the question of how human operators perform actions based on the estimation of visual properties in VR, especially when the sensory cues associated with the same object are conflicting. We report on an experiment in which participants compared the size of a visual sphere to a haptic sphere, belonging to the same object in a VE. The sizes from the visual and haptic modalities were either identical or conflicting (with visual size being larger than haptic size, or vice versa). We used three standard haptic references (small, medium, and large sizes) and asked participants to compare the visual sizes with the given reference, by method of constant stimuli. Results show a dominant functional priority of the visual size perception. Moreover, observers demonstrated a central tendency effect: over-estimation for smaller haptic sizes but under-estimation for larger haptic sizes. The results are in-line with previous studies in real environments (RE). We discuss the current findings in the framework of adaptation level theory for haptic size reference. This work provides important implications for the optimal design of human-computer interactions when integrating 3D visual-haptic information in a VE.
PubMed: 32372939
DOI: 10.3389/fnbot.2020.00018 -
Attention, Perception & Psychophysics Apr 2021Perception, representation, and memory of ensemble statistics has attracted growing interest. Studies found that, at different abstraction levels, the brain represents...
Perception, representation, and memory of ensemble statistics has attracted growing interest. Studies found that, at different abstraction levels, the brain represents similar items as unified percepts. We found that global ensemble perception is automatic and unconscious, affecting later perceptual judgments regarding individual member items. Implicit effects of set mean and range for low-level feature ensembles (size, orientation, brightness) were replicated for high-level category objects. This similarity suggests that analogous mechanisms underlie these extreme levels of abstraction. Here, we bridge the span between visual features and semantic object categories using the identical implicit perception experimental paradigm for intermediate novel visual-shape categories, constructing ensemble exemplars by introducing systematic variations of a central category base or ancestor. In five experiments, with different item variability, we test automatic representation of ensemble category characteristics and its effect on a subsequent memory task. Results show that observer representation of ensembles includes the group's central shape, category ancestor (progenitor), or group mean. Observers also easily reject memory of shapes belonging to different categories, i.e. originating from different ancestors. We conclude that complex categories, like simple visual form ensembles, are represented in terms of statistics including a central object, as well as category boundaries. We refer to the model proposed by Benna and Fusi (bioRxiv 624239, 2019) that memory representation is compressed when related elements are represented by identifying their ancestor and each one's difference from it. We suggest that ensemble mean perception, like category prototype extraction, might reflect employment at different representation levels of an essential, general representation mechanism.
Topics: Brain; Brain Mapping; Concept Formation; Humans; Judgment; Semantics; Visual Perception
PubMed: 33420715
DOI: 10.3758/s13414-020-02174-0 -
Journal of Vision Mar 2021Motion perception is a critical function of the visual system. In a three-dimensional environment, multiple sensory cues carry information about an object's motion...
Motion perception is a critical function of the visual system. In a three-dimensional environment, multiple sensory cues carry information about an object's motion trajectory. Previous work has quantified the contribution of binocular motion cues, such as interocular velocity differences and changing disparities over time, as well as monocular motion cues, such as size and density changes. However, even when these cues are presented in concert, observers will systematically misreport the direction of motion-in-depth. Although in the majority of laboratory experiments head position is held fixed using a chin or head rest, an observer's head position is subject to involuntary small movements under real-world viewing conditions. Here, we considered the potential impact of such "head jitter" on motion-in-depth perception. We presented visual stimuli in a head-mounted virtual reality device that facilitated low latency head tracking and asked observers to judge 3D object motion. We found performance improved when we updated the visual display consistent with the small changes in head position. When we disrupted or delayed head movement-contingent updating of the visual display, the proportion of motion-in-depth misreports again increased, reflected in both a reduction in sensitivity and an increase in bias. Our findings identify a critical function of head jitter in visual motion perception, which has been obscured in most (head-fixed and non-head jitter contingent) laboratory experiments.
Topics: Cues; Depth Perception; Head Movements; Humans; Imaging, Three-Dimensional; Motion Perception; Virtual Reality; Vision, Binocular
PubMed: 33687429
DOI: 10.1167/jov.21.3.12 -
Scientific Reports Sep 2022We investigated whether brief non-judgmental focus on the details of one's non-dominant hand might lead to changes in perception of its size, and if such a change would...
We investigated whether brief non-judgmental focus on the details of one's non-dominant hand might lead to changes in perception of its size, and if such a change would be related to central coherence, body dissatisfaction, or how much participants liked their hand. After two pilot experiments (N = 28 and N = 30 respectively: Appendix 1), a within-subject experiment (N = 82) was conducted. Subjects were mainly university students. They were asked to rate the size of their non-dominant hand and how much they liked it, and the size of an external object (a X-box controller) on a visual-analog scale before and after focusing on their details for 5 min, as well as the size of another object (a calculator) before and after a 5 min long distraction task. After completing the tasks, they were asked to respond to a brief questionnaire on body dissatisfaction. A s significant interaction between time and factors (non-dominant hand, X-box controller and calculator) emerged (F(2, 78) = 6.41, p = .003). Participants rated their hand as larger after focusing on its details compared to baseline, and this change was significantly larger than those reported for the X-box controller. No significant change in how they liked their hand was observed, and contrary to the pilot experiments, the perceived change in size of the hand was not related to body dissatisfaction. The significant change in reporting of the size of the hand after focusing on its details seems to be an interesting finding, worth further replications.
Topics: Hand; Humans; Judgment; Size Perception
PubMed: 36123432
DOI: 10.1038/s41598-022-19919-6 -
Public Health Nutrition Mar 2022To synthesise evidence on body size preferences for females living in Africa and the factors influencing these. (Review)
Review
OBJECTIVE
To synthesise evidence on body size preferences for females living in Africa and the factors influencing these.
DESIGN
Mixed-methods systematic review including searches on Medline, CINHAL, ASSIA, Web of Science and PsycINFO (PROSPERO CRD42015020509). A sequential-explanatory approach was used to integrate quantitative and qualitative findings.
SETTING
Urban and rural Africa.
PARTICIPANTS
Studies of both sexes providing data on body size preferences for adolescent girls and women aged ≥10 years.
RESULTS
Seventy-three articles from twenty-one countries were included: fifty quantitative, fifteen qualitative and eight mixed methods. Most studies reported a preference for normal or overweight body sizes. Some studies of adolescent girls/young women indicated a preference for underweight. Factors influencing preferences for large(r) body sizes included: socio-demographic (e.g. education, rural residency), health-related (e.g. current BMI, pubertal status), psycho-social (e.g. avoiding HIV stigma) and socio-cultural factors (e.g. spouse's preference, social standing, cultural norms). Factors influencing preferences for slim(mer) body sizes included: socio-demographic (e.g. higher socioeconomic status, urban residency, younger age), health-related (e.g. health knowledge, being nulliparous), psycho-social (e.g. appearance, body size perception as overweight/obese) and socio-cultural factors (e.g. peer pressure, media).
CONCLUSIONS
Preference for overweight (not obese) body sizes among some African females means that interventions need to account for the array of factors that maintain these preferences. The widespread preference for normal weight is positive in public health terms, but the valorisation of underweight in adolescent girls/young women may lead to an increase in body dissatisfaction. Emphasis needs to be placed on education to prevent all forms of malnutrition.
Topics: Adolescent; Africa; Body Mass Index; Body Size; Female; Humans; Male; Obesity; Overweight; Thinness
PubMed: 33593472
DOI: 10.1017/S1368980021000768 -
Cognition Aug 2023Weber's law, the principle that the uncertainty of perceptual estimates increases proportionally with object size, is regularly violated when considering the uncertainty...
Weber's law, the principle that the uncertainty of perceptual estimates increases proportionally with object size, is regularly violated when considering the uncertainty of the grip aperture during grasping movements. The origins of this perception-action dissociation are debated and are attributed to various reasons, including different coding of visual size information for perception and action, biomechanical factors, the use of positional information to guide grasping, or, sensorimotor calibration. Here, we contrasted these accounts and compared perceptual and grasping uncertainties by asking people to indicate the visually perceived center of differently sized objects (Perception condition) or to grasp and lift the same objects with the requirement to achieve a balanced lift (Action condition). We found that the variability (uncertainty) of contact positions increased as a function of object size in both perception and action. The adherence of the Action condition to Weber's law and the consequent absence of a perception-action dissociation contradict the predictions based on different coding of visual size information and sensorimotor calibration. These findings provide clear evidence that human perceptual and visuomotor systems rely on the same visual information and suggest that the previously reported violations of Weber's law in grasping movements should be attributed to other factors.
Topics: Humans; Psychomotor Performance; Differential Threshold; Visual Perception; Movement; Hand Strength
PubMed: 37150154
DOI: 10.1016/j.cognition.2023.105465 -
Proceedings. Biological Sciences Jul 2020Perceiving the positions of objects is a prerequisite for most other visual and visuomotor functions, but human perception of object position varies from one individual...
Perceiving the positions of objects is a prerequisite for most other visual and visuomotor functions, but human perception of object position varies from one individual to the next. The source of these individual differences in perceived position and their perceptual consequences are unknown. Here, we tested whether idiosyncratic biases in the underlying representation of visual space propagate across different levels of visual processing. In Experiment 1, using a position matching task, we found stable, observer-specific compressions and expansions within local regions throughout the visual field. We then measured Vernier acuity (Experiment 2) and perceived size of objects (Experiment 3) across the visual field and found that individualized spatial distortions were closely associated with variations in both visual acuity and apparent object size. Our results reveal idiosyncratic biases in perceived position and size, originating from a heterogeneous spatial resolution that carries across the visual hierarchy.
Topics: Humans; Size Perception; Space Perception; Visual Acuity; Visual Fields; Visual Perception
PubMed: 32635869
DOI: 10.1098/rspb.2020.0825