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Abstract
The size-weight illusion is a perceptual illusion where smaller objects are judged as heavier than equally weighted larger objects. A previous informal report suggests that visual form agnosic patient DF does not experience the size-weight illusion when vision is the only available cue to object size. We tested this experimentally, comparing the magnitudes of DF's visual, kinesthetic and visual-kinesthetic size-weight illusions to those of 28 similarly-aged controls. A modified t-test found that DF's visual size-weight illusion was significantly smaller than that of controls (zcc = -1.7). A test of simple dissociation based on the Revised Standardized Difference Test found that the discrepancy between the magnitude of DF's visual and kinesthetic size-weight illusions was not significantly different from that of controls (zdcc = -1.054), thereby failing to establish a dissociation between the visual and kinesthetic conditions. These results are consistent with previous suggestions that visual form agnosia, following ventral visual stream damage, is associated with an abnormally reduced size-weight illusion. The results, however, do not confirm that this reduction is specific to the use of visual size cues to predict object weight, rather than reflecting more general changes in the processing of object size cues or in the use of predictive strategies for lifting.
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Affiliation(s)
| | - Anna Sedda
- School of Social Sciences,Psychology, Heriot-Watt University , Edinburgh, UK
| | | | - Robert D McIntosh
- Human Cognitive Neuroscience, Psychology, University of Edinburgh , Edinburgh, UK
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Pinardi M, Raiano L, Formica D, Di Pino G. Altered Proprioceptive Feedback Influences Movement Kinematics in a Lifting Task. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:3232-3235. [PMID: 33018693 DOI: 10.1109/embc44109.2020.9176252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Movement control process can be considered to take place on at least two different levels: a high, more cognitive level and a low, sensorimotor level. On a high level processing a motor command is planned accordingly to the desired goal and the sensory afference, mainly proprioception, is used to determine the necessary adjustments in order to minimize any discrepancy between predicted and executed action. On a lower level processing, the proprioceptive feedback later employed in high level regulations, is generated by Ia sensory fibers positioned in muscle main proprioceptors: muscle spindles. By entraining the activity of these spindle fibers through 80Hz vibration of triceps distal tendon, we show the intriguing possibility of inducing kinematics adjustments due to negative feedback corrections, during a lifting task.
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Abstract
It is well established that manipulations of low-level stimulus properties unrelated to mass can impact perception of heaviness, the most famous example being the size-weight illusion whereby small objects feel heavier than equally-weighted larger objects. Interestingly, manipulations of high-level cues such as material have also induced weight illusions, highlighting that cognitive expectations alone are enough to create illusory weight differences. Less is known, however, about what type of cognitive expectations can influence perception of heaviness. As labels are often used to signify the heaviness of objects, this study examined whether semantic cues could induce a novel weight illusion. Participants lifted equally-sized and equally-weighted sets of objects labelled as ‘light’ and ‘heavy’ and reported their perceived heaviness both prior to and after lifting. Fingertip forces were also measured to understand how semantic cues may influence sensorimotor prediction. The labels clearly affected pre-lift-off expectations of heaviness. By contrast, we found no effect of these labels on the perceived heaviness of objects, nor on the forces used to grip and lift them on early trials. In other words, we find no evidence that semantic cues affect perception or action enough to induce a novel weight illusion. These findings suggest that the explicit expectations created by the labels did not dominate the implicit expectations created by the equal sizes of the objects, highlighting the segregated nature of cognitive expectations and their variable influences on perception and action.
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4
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Abstract
The current study comprises the first systematic meta-analysis of weight illusions. We obtained descriptive data from studies in which subjective heaviness estimates were made for pairs or groups of objects that had the same mass and different volumes (size-weight illusion; SWI) or different apparent material properties (material-weight illusion; MWI). Using these data, we calculated mean effect sizes to represent illusion strength. Other study details, including stimulus mass, volume, density, and degree of visual and somatosensory access to the stimuli were also recorded to quantify the contribution of these variables to effect sizes for the SWI. The results indicate that the SWI has a larger mean effect size than the MWI and that the former is consistent in strength when information about stimulus size is gained through somatosensory channels, regardless of visual access. The SWI is weaker when only the visual system provides size information. Effect sizes for the SWI were larger when there was a greater difference in volume across the stimuli. There was also a positive correlation between SWI strength and the difference in physical density across the different experimental stimuli, even after controlling for volume differences. Together, we argue that these findings provide support for theories of weight illusions that are based on conceptual expectancies as well as those that are based on bottom-up processing of physical density. We further propose that these processes, which have been considered dichotomously in the past, may not be mutually exclusive from each other and could both contribute to our perception of weight when we handle objects in everyday life.
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Freeman CG, Saccone EJ, Chouinard PA. Low-level sensory processes play a more crucial role than high-level cognitive ones in the size-weight illusion. PLoS One 2019; 14:e0222564. [PMID: 31518376 PMCID: PMC6743775 DOI: 10.1371/journal.pone.0222564] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 09/03/2019] [Indexed: 11/19/2022] Open
Abstract
The size-weight illusion (SWI) pertains to the experience of perceiving the smaller of two equally weighted objects as heavier. Competing theories to explain the illusion can be generally grouped into cognitive and sensory theories, which place more importance on top-down processing of cognitive expectations and bottom-up processing of sensory information about the size and weight of objects, respectively. The current study examined the relative contribution of these two general explanations. This was done by varying the amounts of cognitive load in a dual-task and the quality of somatosensory feedback by wearing or not wearing gloves. Participants placed their hands through a curtain inside a box so they could not see the test objects. Inside the box, they were presented with either a small or large sphere of varying weights, which they explored manually without vision. Participants provided magnitude estimates about each object's weight in four experimental conditions (no-load with gloves, no-load without gloves, low-load without gloves, and high-load without gloves). The dual-task involved the visual presentation of a cross on a computer monitor that changed in both colour and orientation. With foot pedals, the participants responded to a target colour and / or orientation, which varied across conditions, while they hefted an object. Some conditions were designed to be more cognitively taxing than others (high-load > low-load > no-load conditions). The results revealed that the strength of the SWI diminished when participants wore the gloves but did not change as cognitive load increased on the dual-task. We conclude that the illusion is more influenced by bottom-up sensory than top-down cognitive processes.
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Affiliation(s)
- Cody G. Freeman
- Department of Psychology and Counselling, School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
| | - Elizabeth J. Saccone
- Department of Psychology and Counselling, School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
| | - Philippe A. Chouinard
- Department of Psychology and Counselling, School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
- * E-mail:
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Saccone EJ, Goldsmith RM, Buckingham G, Chouinard PA. Container size exerts a stronger influence than liquid volume on the perceived weight of objects. Cognition 2019; 192:104038. [PMID: 31401168 DOI: 10.1016/j.cognition.2019.104038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 08/01/2019] [Accepted: 08/04/2019] [Indexed: 11/26/2022]
Abstract
Many features of an object can influence how we predict and perceive its weight. The current study evaluated the relative contributions of sensory and conceptual processing of object features on weight perception. We employed a novel paradigm to investigate how container size and the amount of liquid inside can influence the perceived weight of bottles and the forces deployed when lifting them. Stimulus pairs always had the same mass but could vary in liquid volume (full vs half-full bottle) or size (large vs small bottle; size-weight illusion (SWI)). In Experiment 1, participants lifted the stimuli via strings, which served to isolate the influence of visual from kinaesthetic information about the size of stimuli on perception and lifting behaviour. In Experiment 2, participants lifted the stimuli via handles that were attached directly to the objects. This lifting style is more likely to include deviations from true vertical lifting, which should theoretically provide more kinaesthetic information about the size of the stimuli. Experiment 1 did not produce any weight illusion. Experiment 2 produced a weight illusion but only when container size differed. Thus, liquid volume did not influence perceived weight when container size was held constant in either experiment. Curiously, additional control experiments revealed that participants could not discriminate between the different sized bottles solely from the kinaesthetic information received from a handle-based lift, suggesting that size might be processed differently when making explicit perceptual judgements about it than when influencing weight perception. Together, these findings suggest that weight illusions are driven more strongly by the kinaesthetic processing of stimulus features than predictions arising from conceptual weight cues.
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Affiliation(s)
- Elizabeth J Saccone
- School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia.
| | - Rachael M Goldsmith
- School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
| | - Gavin Buckingham
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Philippe A Chouinard
- School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
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Saccone EJ, Chouinard PA. The influence of size in weight illusions is unique relative to other object features. Psychon Bull Rev 2019; 26:77-89. [PMID: 30187441 DOI: 10.3758/s13423-018-1519-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Research into weight illusions has provided valuable insight into the functioning of the human perceptual system. Associations between the weight of an object and its other features, such as its size, material, density, conceptual information, or identity, influence our expectations and perceptions of weight. Earlier accounts of weight illusions underscored the importance of previous interactions with objects in the formation of these associations. In this review, we propose a theory that the influence of size on weight perception could be driven by innate and phylogenetically older mechanisms, and that it is therefore more deep-seated than the effects of other features that influence our perception of an object's weight. To do so, we first consider the different associations that exist between the weight of an object and its other features and discuss how different object features influence weight perception in different weight illusions. After this, we consider the cognitive, neurological, and developmental evidence, highlighting the uniqueness of size-weight associations and how they might be reinforced rather than driven by experience alone. In the process, we propose a novel neuroanatomical account of how size might influence weight perception differently than other object features do.
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Affiliation(s)
- Elizabeth J Saccone
- School of Psychology and Public Health, La Trobe University, Edwards Road, Flora Hill, Victoria, 3552, Australia.
| | - Philippe A Chouinard
- School of Psychology and Public Health, La Trobe University, Edwards Road, Flora Hill, Victoria, 3552, Australia
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Buckingham G, Parr J, Wood G, Vine S, Dimitriou P, Day S. The impact of using an upper-limb prosthesis on the perception of real and illusory weight differences. Psychon Bull Rev 2018; 25:1507-1516. [PMID: 29352411 PMCID: PMC6096644 DOI: 10.3758/s13423-017-1425-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Little is known about how human perception is affected using an upper-limb prosthesis. To shed light on this topic, we investigated how using an upper-limb prosthesis affects individuals' experience of object weight. First, we examined how a group of upper-limb amputee prosthetic users experienced real mass differences and illusory weight differences in the context of the 'size-weight' illusion. Surprisingly, the upper-limb prosthetic users reported a markedly smaller illusion than controls, despite equivalent perceptions of a real mass difference. Next, we replicated this dissociation between real and illusory weight perception in a group of nonamputees who lifted the stimuli with an upper-limb myoelectric prosthetic simulator, again noting that the prosthetic users experienced illusory, but not real, weight differences as being weaker than controls. These findings not only validate the use of a prosthetic simulator as an effective tool for investigating perception and action but also highlight a surprising dissociation between the perception of real and illusory weight differences.
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Affiliation(s)
- Gavin Buckingham
- Department of Sport and Health Sciences, University of Exeter, Richard's Building, St. Luke's Campus, Exeter, UK.
| | - Johnny Parr
- Department of Health Sciences, Liverpool Hope University, Liverpool, UK
| | - Greg Wood
- Centre for Health, Exercise and Active Living, Manchester Metropolitan University, Crewe, UK
| | - Samuel Vine
- Department of Sport and Health Sciences, University of Exeter, Richard's Building, St. Luke's Campus, Exeter, UK
| | - Pan Dimitriou
- Psychology Department, Heriot-Watt University, Edinburgh, UK
| | - Sarah Day
- National Centre for Prosthetics and Orthotics, Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK
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Buckingham G, Reid D, Potter L. How Prior Expectations Influence Older Adults’ Perception and Action During Object Interaction. Multisens Res 2018; 31:301-316. [DOI: 10.1163/22134808-00002585] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 04/26/2017] [Indexed: 11/19/2022]
Abstract
The apparent size of an object can influence how we interact with and perceive the weight of objects in our environment. Little is known, however, about how this cue affects behaviour across the lifespan. Here, in the context of the size–weight illusion, we examined how visual size cues influenced the predictive application of fingertip forces and perceptions of heaviness in a group of older participants. We found that our older sample experienced a robust size–weight illusion, which did not differ from that experienced by younger participants. Older and young participants also experienced a real weight difference to a similar degree. By contrast, compared to younger participants our older group showed no evidence that size cues influenced the way they initially gripped and lifted the objects. These results highlight a unique dissociation between how perception and action diverge across the lifespan, and suggest that deficits in the ability to use prediction to guide actions might underpin some of the manual interaction difficulties experienced by the older adults.
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Affiliation(s)
- Gavin Buckingham
- Department of Sport and Health Sciences, Richards Building, University of Exeter, UK
| | - Darren Reid
- Department of Psychology, Heriot-Watt University, UK
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Ramakrishnan T, Schlafly M, Reed KB. Evaluation of 3D printed anatomically scalable transfemoral prosthetic knee. IEEE Int Conf Rehabil Robot 2017; 2017:1160-1164. [PMID: 28813978 DOI: 10.1109/icorr.2017.8009406] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This case study compares a transfemoral amputee's gait while using the existing Ossur Total Knee 2000 and our novel 3D printed anatomically scalable transfemoral prosthetic knee. The anatomically scalable transfemoral prosthetic knee is 3D printed out of a carbon-fiber and nylon composite that has a gear-mesh coupling with a hard-stop weight-actuated locking mechanism aided by a cross-linked four-bar spring mechanism. This design can be scaled using anatomical dimensions of a human femur and tibia to have a unique fit for each user. The transfemoral amputee who was tested is high functioning and walked on the Computer Assisted Rehabilitation Environment (CAREN) at a self-selected pace. The motion capture and force data that was collected showed that there were distinct differences in the gait dynamics. The data was used to perform the Combined Gait Asymmetry Metric (CGAM), where the scores revealed that the overall asymmetry of the gait on the Ossur Total Knee was more asymmetric than the anatomically scalable transfemoral prosthetic knee. The anatomically scalable transfemoral prosthetic knee had higher peak knee flexion that caused a large step time asymmetry. This made walking on the anatomically scalable transfemoral prosthetic knee more strenuous due to the compensatory movements in adapting to the different dynamics. This can be overcome by tuning the cross-linked spring mechanism to emulate the dynamics of the subject better. The subject stated that the knee would be good for daily use and has the potential to be adapted as a running knee.
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Cashaback JGA, McGregor HR, Pun HCH, Buckingham G, Gribble PL. Does the sensorimotor system minimize prediction error or select the most likely prediction during object lifting? J Neurophysiol 2016; 117:260-274. [PMID: 27760821 DOI: 10.1152/jn.00609.2016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 10/19/2016] [Indexed: 11/22/2022] Open
Abstract
The human sensorimotor system is routinely capable of making accurate predictions about an object's weight, which allows for energetically efficient lifts and prevents objects from being dropped. Often, however, poor predictions arise when the weight of an object can vary and sensory cues about object weight are sparse (e.g., picking up an opaque water bottle). The question arises, what strategies does the sensorimotor system use to make weight predictions when one is dealing with an object whose weight may vary? For example, does the sensorimotor system use a strategy that minimizes prediction error (minimal squared error) or one that selects the weight that is most likely to be correct (maximum a posteriori)? In this study we dissociated the predictions of these two strategies by having participants lift an object whose weight varied according to a skewed probability distribution. We found, using a small range of weight uncertainty, that four indexes of sensorimotor prediction (grip force rate, grip force, load force rate, and load force) were consistent with a feedforward strategy that minimizes the square of prediction errors. These findings match research in the visuomotor system, suggesting parallels in underlying processes. We interpret our findings within a Bayesian framework and discuss the potential benefits of using a minimal squared error strategy. NEW & NOTEWORTHY Using a novel experimental model of object lifting, we tested whether the sensorimotor system models the weight of objects by minimizing lifting errors or by selecting the statistically most likely weight. We found that the sensorimotor system minimizes the square of prediction errors for object lifting. This parallels the results of studies that investigated visually guided reaching, suggesting an overlap in the underlying mechanisms between tasks that involve different sensory systems.
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Affiliation(s)
- Joshua G A Cashaback
- Brain and Mind Institute, Department of Psychology, Western University, London, Ontario, Canada;
| | - Heather R McGregor
- Brain and Mind Institute, Department of Psychology, Western University, London, Ontario, Canada.,Graduate Program in Neuroscience, Western University, London, Ontario, Canada
| | - Henry C H Pun
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada; and
| | - Gavin Buckingham
- Department of Sport and Health Sciences, University of Exeter, Devon, United Kingdom
| | - Paul L Gribble
- Brain and Mind Institute, Department of Psychology, Western University, London, Ontario, Canada.,Department of Physiology and Pharmacology, Western University, London, Ontario, Canada; and
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